[PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

DRM bridge drivers are now attaching their DSI device at probe time,
which requires us to register our DSI host in order to let the bridge
to probe: this recently started producing an endless -EPROBE_DEFER
loop on some machines that are using external bridges, like the
parade-ps8640, found on the ACER Chromebook R13.

Now that the DSI hosts/devices probe sequence is documented, we can
do adjustments to the mtk_dsi driver as to both fix now and make sure
to avoid this situation in the future: for this, following what is
documented in drm_bridge.c, move the mtk_dsi component_add() to the
mtk_dsi_ops.attach callback and delete it in the detach callback;
keeping in mind that we are registering a drm_bridge for our DSI,
which is only used/attached if the DSI Host is bound, it wouldn't
make sense to keep adding our bridge at probe time (as it would
be useless to have it if mtk_dsi_ops.attach() fails!), so also move
that one to the dsi host attach function (and remove it in detach).

Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
 1 file changed, 84 insertions(+), 83 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 5d90d2eb0019..bced4c7d668e 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
 	mtk_dsi_poweroff(dsi);
 }
 
+static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
+{
+	int ret;
+
+	ret = drm_simple_encoder_init(drm, &dsi->encoder,
+				      DRM_MODE_ENCODER_DSI);
+	if (ret) {
+		DRM_ERROR("Failed to encoder init to drm\n");
+		return ret;
+	}
+
+	dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
+
+	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
+				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+	if (ret)
+		goto err_cleanup_encoder;
+
+	dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
+	if (IS_ERR(dsi->connector)) {
+		DRM_ERROR("Unable to create bridge connector\n");
+		ret = PTR_ERR(dsi->connector);
+		goto err_cleanup_encoder;
+	}
+	drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
+
+	return 0;
+
+err_cleanup_encoder:
+	drm_encoder_cleanup(&dsi->encoder);
+	return ret;
+}
+
+static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
+{
+	int ret;
+	struct drm_device *drm = data;
+	struct mtk_dsi *dsi = dev_get_drvdata(dev);
+
+	ret = mtk_dsi_encoder_init(drm, dsi);
+	if (ret)
+		return ret;
+
+	return device_reset_optional(dev);
+}
+
+static void mtk_dsi_unbind(struct device *dev, struct device *master,
+			   void *data)
+{
+	struct mtk_dsi *dsi = dev_get_drvdata(dev);
+
+	drm_encoder_cleanup(&dsi->encoder);
+}
+
+static const struct component_ops mtk_dsi_component_ops = {
+	.bind = mtk_dsi_bind,
+	.unbind = mtk_dsi_unbind,
+};
+
 static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
 			       struct mipi_dsi_device *device)
 {
 	struct mtk_dsi *dsi = host_to_dsi(host);
+	struct device *dev = host->dev;
+	int ret;
 
 	dsi->lanes = device->lanes;
 	dsi->format = device->format;
 	dsi->mode_flags = device->mode_flags;
+	dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
+	if (IS_ERR(dsi->next_bridge))
+		return PTR_ERR(dsi->next_bridge);
+
+	drm_bridge_add(&dsi->bridge);
+
+	ret = component_add(host->dev, &mtk_dsi_component_ops);
+	if (ret) {
+		DRM_ERROR("failed to add dsi_host component: %d\n", ret);
+		drm_bridge_remove(&dsi->bridge);
+		return ret;
+	}
 
 	return 0;
 }
 
+static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
+			       struct mipi_dsi_device *device)
+{
+	struct mtk_dsi *dsi = host_to_dsi(host);
+
+	component_del(host->dev, &mtk_dsi_component_ops);
+	drm_bridge_remove(&dsi->bridge);
+	return 0;
+}
+
 static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
 {
 	int ret;
@@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
 
 static const struct mipi_dsi_host_ops mtk_dsi_ops = {
 	.attach = mtk_dsi_host_attach,
+	.detach = mtk_dsi_host_detach,
 	.transfer = mtk_dsi_host_transfer,
 };
 
-static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
-{
-	int ret;
-
-	ret = drm_simple_encoder_init(drm, &dsi->encoder,
-				      DRM_MODE_ENCODER_DSI);
-	if (ret) {
-		DRM_ERROR("Failed to encoder init to drm\n");
-		return ret;
-	}
-
-	dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
-
-	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
-				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
-	if (ret)
-		goto err_cleanup_encoder;
-
-	dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
-	if (IS_ERR(dsi->connector)) {
-		DRM_ERROR("Unable to create bridge connector\n");
-		ret = PTR_ERR(dsi->connector);
-		goto err_cleanup_encoder;
-	}
-	drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
-
-	return 0;
-
-err_cleanup_encoder:
-	drm_encoder_cleanup(&dsi->encoder);
-	return ret;
-}
-
-static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
-{
-	int ret;
-	struct drm_device *drm = data;
-	struct mtk_dsi *dsi = dev_get_drvdata(dev);
-
-	ret = mtk_dsi_encoder_init(drm, dsi);
-	if (ret)
-		return ret;
-
-	return device_reset_optional(dev);
-}
-
-static void mtk_dsi_unbind(struct device *dev, struct device *master,
-			   void *data)
-{
-	struct mtk_dsi *dsi = dev_get_drvdata(dev);
-
-	drm_encoder_cleanup(&dsi->encoder);
-}
-
-static const struct component_ops mtk_dsi_component_ops = {
-	.bind = mtk_dsi_bind,
-	.unbind = mtk_dsi_unbind,
-};
-
 static int mtk_dsi_probe(struct platform_device *pdev)
 {
 	struct mtk_dsi *dsi;
 	struct device *dev = &pdev->dev;
-	struct drm_panel *panel;
 	struct resource *regs;
 	int irq_num;
 	int ret;
@@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
-					  &panel, &dsi->next_bridge);
-	if (ret)
-		goto err_unregister_host;
-
-	if (panel) {
-		dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
-		if (IS_ERR(dsi->next_bridge)) {
-			ret = PTR_ERR(dsi->next_bridge);
-			goto err_unregister_host;
-		}
-	}
-
 	dsi->driver_data = of_device_get_match_data(dev);
 
 	dsi->engine_clk = devm_clk_get(dev, "engine");
@@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
 	dsi->bridge.of_node = dev->of_node;
 	dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
 
-	drm_bridge_add(&dsi->bridge);
-
-	ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to add component: %d\n", ret);
-		goto err_unregister_host;
-	}
-
 	return 0;
 
 err_unregister_host:
@@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
 	struct mtk_dsi *dsi = platform_get_drvdata(pdev);
 
 	mtk_output_dsi_disable(dsi);
-	drm_bridge_remove(&dsi->bridge);
-	component_del(&pdev->dev, &mtk_dsi_component_ops);
 	mipi_dsi_host_unregister(&dsi->host);
 
 	return 0;
-- 
2.33.1

[PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

DRM bridge drivers are now attaching their DSI device at probe time,
which requires us to register our DSI host in order to let the bridge
to probe: this recently started producing an endless -EPROBE_DEFER
loop on some machines that are using external bridges, like the
parade-ps8640, found on the ACER Chromebook R13.

Now that the DSI hosts/devices probe sequence is documented, we can
do adjustments to the mtk_dsi driver as to both fix now and make sure
to avoid this situation in the future: for this, following what is
documented in drm_bridge.c, move the mtk_dsi component_add() to the
mtk_dsi_ops.attach callback and delete it in the detach callback;
keeping in mind that we are registering a drm_bridge for our DSI,
which is only used/attached if the DSI Host is bound, it wouldn't
make sense to keep adding our bridge at probe time (as it would
be useless to have it if mtk_dsi_ops.attach() fails!), so also move
that one to the dsi host attach function (and remove it in detach).

Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
 1 file changed, 84 insertions(+), 83 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 5d90d2eb0019..bced4c7d668e 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
 	mtk_dsi_poweroff(dsi);
 }
 
+static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
+{
+	int ret;
+
+	ret = drm_simple_encoder_init(drm, &dsi->encoder,
+				      DRM_MODE_ENCODER_DSI);
+	if (ret) {
+		DRM_ERROR("Failed to encoder init to drm\n");
+		return ret;
+	}
+
+	dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
+
+	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
+				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+	if (ret)
+		goto err_cleanup_encoder;
+
+	dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
+	if (IS_ERR(dsi->connector)) {
+		DRM_ERROR("Unable to create bridge connector\n");
+		ret = PTR_ERR(dsi->connector);
+		goto err_cleanup_encoder;
+	}
+	drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
+
+	return 0;
+
+err_cleanup_encoder:
+	drm_encoder_cleanup(&dsi->encoder);
+	return ret;
+}
+
+static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
+{
+	int ret;
+	struct drm_device *drm = data;
+	struct mtk_dsi *dsi = dev_get_drvdata(dev);
+
+	ret = mtk_dsi_encoder_init(drm, dsi);
+	if (ret)
+		return ret;
+
+	return device_reset_optional(dev);
+}
+
+static void mtk_dsi_unbind(struct device *dev, struct device *master,
+			   void *data)
+{
+	struct mtk_dsi *dsi = dev_get_drvdata(dev);
+
+	drm_encoder_cleanup(&dsi->encoder);
+}
+
+static const struct component_ops mtk_dsi_component_ops = {
+	.bind = mtk_dsi_bind,
+	.unbind = mtk_dsi_unbind,
+};
+
 static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
 			       struct mipi_dsi_device *device)
 {
 	struct mtk_dsi *dsi = host_to_dsi(host);
+	struct device *dev = host->dev;
+	int ret;
 
 	dsi->lanes = device->lanes;
 	dsi->format = device->format;
 	dsi->mode_flags = device->mode_flags;
+	dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
+	if (IS_ERR(dsi->next_bridge))
+		return PTR_ERR(dsi->next_bridge);
+
+	drm_bridge_add(&dsi->bridge);
+
+	ret = component_add(host->dev, &mtk_dsi_component_ops);
+	if (ret) {
+		DRM_ERROR("failed to add dsi_host component: %d\n", ret);
+		drm_bridge_remove(&dsi->bridge);
+		return ret;
+	}
 
 	return 0;
 }
 
+static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
+			       struct mipi_dsi_device *device)
+{
+	struct mtk_dsi *dsi = host_to_dsi(host);
+
+	component_del(host->dev, &mtk_dsi_component_ops);
+	drm_bridge_remove(&dsi->bridge);
+	return 0;
+}
+
 static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
 {
 	int ret;
@@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
 
 static const struct mipi_dsi_host_ops mtk_dsi_ops = {
 	.attach = mtk_dsi_host_attach,
+	.detach = mtk_dsi_host_detach,
 	.transfer = mtk_dsi_host_transfer,
 };
 
-static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
-{
-	int ret;
-
-	ret = drm_simple_encoder_init(drm, &dsi->encoder,
-				      DRM_MODE_ENCODER_DSI);
-	if (ret) {
-		DRM_ERROR("Failed to encoder init to drm\n");
-		return ret;
-	}
-
-	dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
-
-	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
-				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
-	if (ret)
-		goto err_cleanup_encoder;
-
-	dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
-	if (IS_ERR(dsi->connector)) {
-		DRM_ERROR("Unable to create bridge connector\n");
-		ret = PTR_ERR(dsi->connector);
-		goto err_cleanup_encoder;
-	}
-	drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
-
-	return 0;
-
-err_cleanup_encoder:
-	drm_encoder_cleanup(&dsi->encoder);
-	return ret;
-}
-
-static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
-{
-	int ret;
-	struct drm_device *drm = data;
-	struct mtk_dsi *dsi = dev_get_drvdata(dev);
-
-	ret = mtk_dsi_encoder_init(drm, dsi);
-	if (ret)
-		return ret;
-
-	return device_reset_optional(dev);
-}
-
-static void mtk_dsi_unbind(struct device *dev, struct device *master,
-			   void *data)
-{
-	struct mtk_dsi *dsi = dev_get_drvdata(dev);
-
-	drm_encoder_cleanup(&dsi->encoder);
-}
-
-static const struct component_ops mtk_dsi_component_ops = {
-	.bind = mtk_dsi_bind,
-	.unbind = mtk_dsi_unbind,
-};
-
 static int mtk_dsi_probe(struct platform_device *pdev)
 {
 	struct mtk_dsi *dsi;
 	struct device *dev = &pdev->dev;
-	struct drm_panel *panel;
 	struct resource *regs;
 	int irq_num;
 	int ret;
@@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
-					  &panel, &dsi->next_bridge);
-	if (ret)
-		goto err_unregister_host;
-
-	if (panel) {
-		dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
-		if (IS_ERR(dsi->next_bridge)) {
-			ret = PTR_ERR(dsi->next_bridge);
-			goto err_unregister_host;
-		}
-	}
-
 	dsi->driver_data = of_device_get_match_data(dev);
 
 	dsi->engine_clk = devm_clk_get(dev, "engine");
@@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
 	dsi->bridge.of_node = dev->of_node;
 	dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
 
-	drm_bridge_add(&dsi->bridge);
-
-	ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to add component: %d\n", ret);
-		goto err_unregister_host;
-	}
-
 	return 0;
 
 err_unregister_host:
@@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
 	struct mtk_dsi *dsi = platform_get_drvdata(pdev);
 
 	mtk_output_dsi_disable(dsi);
-	drm_bridge_remove(&dsi->bridge);
-	component_del(&pdev->dev, &mtk_dsi_component_ops);
 	mipi_dsi_host_unregister(&dsi->host);
 
 	return 0;
-- 
2.33.1

[PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

DRM bridge drivers are now attaching their DSI device at probe time,
which requires us to register our DSI host in order to let the bridge
to probe: this recently started producing an endless -EPROBE_DEFER
loop on some machines that are using external bridges, like the
parade-ps8640, found on the ACER Chromebook R13.

Now that the DSI hosts/devices probe sequence is documented, we can
do adjustments to the mtk_dsi driver as to both fix now and make sure
to avoid this situation in the future: for this, following what is
documented in drm_bridge.c, move the mtk_dsi component_add() to the
mtk_dsi_ops.attach callback and delete it in the detach callback;
keeping in mind that we are registering a drm_bridge for our DSI,
which is only used/attached if the DSI Host is bound, it wouldn't
make sense to keep adding our bridge at probe time (as it would
be useless to have it if mtk_dsi_ops.attach() fails!), so also move
that one to the dsi host attach function (and remove it in detach).

Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
 1 file changed, 84 insertions(+), 83 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 5d90d2eb0019..bced4c7d668e 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
 	mtk_dsi_poweroff(dsi);
 }
 
+static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
+{
+	int ret;
+
+	ret = drm_simple_encoder_init(drm, &dsi->encoder,
+				      DRM_MODE_ENCODER_DSI);
+	if (ret) {
+		DRM_ERROR("Failed to encoder init to drm\n");
+		return ret;
+	}
+
+	dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
+
+	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
+				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+	if (ret)
+		goto err_cleanup_encoder;
+
+	dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
+	if (IS_ERR(dsi->connector)) {
+		DRM_ERROR("Unable to create bridge connector\n");
+		ret = PTR_ERR(dsi->connector);
+		goto err_cleanup_encoder;
+	}
+	drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
+
+	return 0;
+
+err_cleanup_encoder:
+	drm_encoder_cleanup(&dsi->encoder);
+	return ret;
+}
+
+static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
+{
+	int ret;
+	struct drm_device *drm = data;
+	struct mtk_dsi *dsi = dev_get_drvdata(dev);
+
+	ret = mtk_dsi_encoder_init(drm, dsi);
+	if (ret)
+		return ret;
+
+	return device_reset_optional(dev);
+}
+
+static void mtk_dsi_unbind(struct device *dev, struct device *master,
+			   void *data)
+{
+	struct mtk_dsi *dsi = dev_get_drvdata(dev);
+
+	drm_encoder_cleanup(&dsi->encoder);
+}
+
+static const struct component_ops mtk_dsi_component_ops = {
+	.bind = mtk_dsi_bind,
+	.unbind = mtk_dsi_unbind,
+};
+
 static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
 			       struct mipi_dsi_device *device)
 {
 	struct mtk_dsi *dsi = host_to_dsi(host);
+	struct device *dev = host->dev;
+	int ret;
 
 	dsi->lanes = device->lanes;
 	dsi->format = device->format;
 	dsi->mode_flags = device->mode_flags;
+	dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
+	if (IS_ERR(dsi->next_bridge))
+		return PTR_ERR(dsi->next_bridge);
+
+	drm_bridge_add(&dsi->bridge);
+
+	ret = component_add(host->dev, &mtk_dsi_component_ops);
+	if (ret) {
+		DRM_ERROR("failed to add dsi_host component: %d\n", ret);
+		drm_bridge_remove(&dsi->bridge);
+		return ret;
+	}
 
 	return 0;
 }
 
+static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
+			       struct mipi_dsi_device *device)
+{
+	struct mtk_dsi *dsi = host_to_dsi(host);
+
+	component_del(host->dev, &mtk_dsi_component_ops);
+	drm_bridge_remove(&dsi->bridge);
+	return 0;
+}
+
 static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
 {
 	int ret;
@@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
 
 static const struct mipi_dsi_host_ops mtk_dsi_ops = {
 	.attach = mtk_dsi_host_attach,
+	.detach = mtk_dsi_host_detach,
 	.transfer = mtk_dsi_host_transfer,
 };
 
-static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
-{
-	int ret;
-
-	ret = drm_simple_encoder_init(drm, &dsi->encoder,
-				      DRM_MODE_ENCODER_DSI);
-	if (ret) {
-		DRM_ERROR("Failed to encoder init to drm\n");
-		return ret;
-	}
-
-	dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
-
-	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
-				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
-	if (ret)
-		goto err_cleanup_encoder;
-
-	dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
-	if (IS_ERR(dsi->connector)) {
-		DRM_ERROR("Unable to create bridge connector\n");
-		ret = PTR_ERR(dsi->connector);
-		goto err_cleanup_encoder;
-	}
-	drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
-
-	return 0;
-
-err_cleanup_encoder:
-	drm_encoder_cleanup(&dsi->encoder);
-	return ret;
-}
-
-static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
-{
-	int ret;
-	struct drm_device *drm = data;
-	struct mtk_dsi *dsi = dev_get_drvdata(dev);
-
-	ret = mtk_dsi_encoder_init(drm, dsi);
-	if (ret)
-		return ret;
-
-	return device_reset_optional(dev);
-}
-
-static void mtk_dsi_unbind(struct device *dev, struct device *master,
-			   void *data)
-{
-	struct mtk_dsi *dsi = dev_get_drvdata(dev);
-
-	drm_encoder_cleanup(&dsi->encoder);
-}
-
-static const struct component_ops mtk_dsi_component_ops = {
-	.bind = mtk_dsi_bind,
-	.unbind = mtk_dsi_unbind,
-};
-
 static int mtk_dsi_probe(struct platform_device *pdev)
 {
 	struct mtk_dsi *dsi;
 	struct device *dev = &pdev->dev;
-	struct drm_panel *panel;
 	struct resource *regs;
 	int irq_num;
 	int ret;
@@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
-					  &panel, &dsi->next_bridge);
-	if (ret)
-		goto err_unregister_host;
-
-	if (panel) {
-		dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
-		if (IS_ERR(dsi->next_bridge)) {
-			ret = PTR_ERR(dsi->next_bridge);
-			goto err_unregister_host;
-		}
-	}
-
 	dsi->driver_data = of_device_get_match_data(dev);
 
 	dsi->engine_clk = devm_clk_get(dev, "engine");
@@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
 	dsi->bridge.of_node = dev->of_node;
 	dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
 
-	drm_bridge_add(&dsi->bridge);
-
-	ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to add component: %d\n", ret);
-		goto err_unregister_host;
-	}
-
 	return 0;
 
 err_unregister_host:
@@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
 	struct mtk_dsi *dsi = platform_get_drvdata(pdev);
 
 	mtk_output_dsi_disable(dsi);
-	drm_bridge_remove(&dsi->bridge);
-	component_del(&pdev->dev, &mtk_dsi_component_ops);
 	mipi_dsi_host_unregister(&dsi->host);
 
 	return 0;
-- 
2.33.1


_______________________________________________
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http://lists.infradead.org/mailman/listinfo/linux-mediatek

[PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

DRM bridge drivers are now attaching their DSI device at probe time,
which requires us to register our DSI host in order to let the bridge
to probe: this recently started producing an endless -EPROBE_DEFER
loop on some machines that are using external bridges, like the
parade-ps8640, found on the ACER Chromebook R13.

Now that the DSI hosts/devices probe sequence is documented, we can
do adjustments to the mtk_dsi driver as to both fix now and make sure
to avoid this situation in the future: for this, following what is
documented in drm_bridge.c, move the mtk_dsi component_add() to the
mtk_dsi_ops.attach callback and delete it in the detach callback;
keeping in mind that we are registering a drm_bridge for our DSI,
which is only used/attached if the DSI Host is bound, it wouldn't
make sense to keep adding our bridge at probe time (as it would
be useless to have it if mtk_dsi_ops.attach() fails!), so also move
that one to the dsi host attach function (and remove it in detach).

Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>

---
 drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
 1 file changed, 84 insertions(+), 83 deletions(-)

diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
index 5d90d2eb0019..bced4c7d668e 100644
--- a/drivers/gpu/drm/mediatek/mtk_dsi.c
+++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
@@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
 	mtk_dsi_poweroff(dsi);
 }
 
+static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
+{
+	int ret;
+
+	ret = drm_simple_encoder_init(drm, &dsi->encoder,
+				      DRM_MODE_ENCODER_DSI);
+	if (ret) {
+		DRM_ERROR("Failed to encoder init to drm\n");
+		return ret;
+	}
+
+	dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
+
+	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
+				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
+	if (ret)
+		goto err_cleanup_encoder;
+
+	dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
+	if (IS_ERR(dsi->connector)) {
+		DRM_ERROR("Unable to create bridge connector\n");
+		ret = PTR_ERR(dsi->connector);
+		goto err_cleanup_encoder;
+	}
+	drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
+
+	return 0;
+
+err_cleanup_encoder:
+	drm_encoder_cleanup(&dsi->encoder);
+	return ret;
+}
+
+static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
+{
+	int ret;
+	struct drm_device *drm = data;
+	struct mtk_dsi *dsi = dev_get_drvdata(dev);
+
+	ret = mtk_dsi_encoder_init(drm, dsi);
+	if (ret)
+		return ret;
+
+	return device_reset_optional(dev);
+}
+
+static void mtk_dsi_unbind(struct device *dev, struct device *master,
+			   void *data)
+{
+	struct mtk_dsi *dsi = dev_get_drvdata(dev);
+
+	drm_encoder_cleanup(&dsi->encoder);
+}
+
+static const struct component_ops mtk_dsi_component_ops = {
+	.bind = mtk_dsi_bind,
+	.unbind = mtk_dsi_unbind,
+};
+
 static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
 			       struct mipi_dsi_device *device)
 {
 	struct mtk_dsi *dsi = host_to_dsi(host);
+	struct device *dev = host->dev;
+	int ret;
 
 	dsi->lanes = device->lanes;
 	dsi->format = device->format;
 	dsi->mode_flags = device->mode_flags;
+	dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
+	if (IS_ERR(dsi->next_bridge))
+		return PTR_ERR(dsi->next_bridge);
+
+	drm_bridge_add(&dsi->bridge);
+
+	ret = component_add(host->dev, &mtk_dsi_component_ops);
+	if (ret) {
+		DRM_ERROR("failed to add dsi_host component: %d\n", ret);
+		drm_bridge_remove(&dsi->bridge);
+		return ret;
+	}
 
 	return 0;
 }
 
+static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
+			       struct mipi_dsi_device *device)
+{
+	struct mtk_dsi *dsi = host_to_dsi(host);
+
+	component_del(host->dev, &mtk_dsi_component_ops);
+	drm_bridge_remove(&dsi->bridge);
+	return 0;
+}
+
 static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
 {
 	int ret;
@@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
 
 static const struct mipi_dsi_host_ops mtk_dsi_ops = {
 	.attach = mtk_dsi_host_attach,
+	.detach = mtk_dsi_host_detach,
 	.transfer = mtk_dsi_host_transfer,
 };
 
-static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
-{
-	int ret;
-
-	ret = drm_simple_encoder_init(drm, &dsi->encoder,
-				      DRM_MODE_ENCODER_DSI);
-	if (ret) {
-		DRM_ERROR("Failed to encoder init to drm\n");
-		return ret;
-	}
-
-	dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
-
-	ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
-				DRM_BRIDGE_ATTACH_NO_CONNECTOR);
-	if (ret)
-		goto err_cleanup_encoder;
-
-	dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
-	if (IS_ERR(dsi->connector)) {
-		DRM_ERROR("Unable to create bridge connector\n");
-		ret = PTR_ERR(dsi->connector);
-		goto err_cleanup_encoder;
-	}
-	drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
-
-	return 0;
-
-err_cleanup_encoder:
-	drm_encoder_cleanup(&dsi->encoder);
-	return ret;
-}
-
-static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
-{
-	int ret;
-	struct drm_device *drm = data;
-	struct mtk_dsi *dsi = dev_get_drvdata(dev);
-
-	ret = mtk_dsi_encoder_init(drm, dsi);
-	if (ret)
-		return ret;
-
-	return device_reset_optional(dev);
-}
-
-static void mtk_dsi_unbind(struct device *dev, struct device *master,
-			   void *data)
-{
-	struct mtk_dsi *dsi = dev_get_drvdata(dev);
-
-	drm_encoder_cleanup(&dsi->encoder);
-}
-
-static const struct component_ops mtk_dsi_component_ops = {
-	.bind = mtk_dsi_bind,
-	.unbind = mtk_dsi_unbind,
-};
-
 static int mtk_dsi_probe(struct platform_device *pdev)
 {
 	struct mtk_dsi *dsi;
 	struct device *dev = &pdev->dev;
-	struct drm_panel *panel;
 	struct resource *regs;
 	int irq_num;
 	int ret;
@@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
-					  &panel, &dsi->next_bridge);
-	if (ret)
-		goto err_unregister_host;
-
-	if (panel) {
-		dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
-		if (IS_ERR(dsi->next_bridge)) {
-			ret = PTR_ERR(dsi->next_bridge);
-			goto err_unregister_host;
-		}
-	}
-
 	dsi->driver_data = of_device_get_match_data(dev);
 
 	dsi->engine_clk = devm_clk_get(dev, "engine");
@@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
 	dsi->bridge.of_node = dev->of_node;
 	dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
 
-	drm_bridge_add(&dsi->bridge);
-
-	ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
-	if (ret) {
-		dev_err(&pdev->dev, "failed to add component: %d\n", ret);
-		goto err_unregister_host;
-	}
-
 	return 0;
 
 err_unregister_host:
@@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
 	struct mtk_dsi *dsi = platform_get_drvdata(pdev);
 
 	mtk_output_dsi_disable(dsi);
-	drm_bridge_remove(&dsi->bridge);
-	component_del(&pdev->dev, &mtk_dsi_component_ops);
 	mipi_dsi_host_unregister(&dsi->host);
 
 	return 0;
-- 
2.33.1


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Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[Chun-Kuang Hu]

Hi, Angelo:

AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
2022年1月27日 週四 下午10:36寫道：
>
> DRM bridge drivers are now attaching their DSI device at probe time,
> which requires us to register our DSI host in order to let the bridge
> to probe: this recently started producing an endless -EPROBE_DEFER
> loop on some machines that are using external bridges, like the
> parade-ps8640, found on the ACER Chromebook R13.
>
> Now that the DSI hosts/devices probe sequence is documented, we can
> do adjustments to the mtk_dsi driver as to both fix now and make sure
> to avoid this situation in the future: for this, following what is
> documented in drm_bridge.c, move the mtk_dsi component_add() to the
> mtk_dsi_ops.attach callback and delete it in the detach callback;
> keeping in mind that we are registering a drm_bridge for our DSI,
> which is only used/attached if the DSI Host is bound, it wouldn't
> make sense to keep adding our bridge at probe time (as it would
> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
> that one to the dsi host attach function (and remove it in detach).
>
> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")

The fixed tag should indicate the patch which cause the bug, but why a
patch just adding document would cause bug?
So no any patch cause bug? This patch just want to prevent a possible bug?

Regards,
Chun-Kuang.

> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>  1 file changed, 84 insertions(+), 83 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 5d90d2eb0019..bced4c7d668e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
>         mtk_dsi_poweroff(dsi);
>  }
>
> +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
> +{
> +       int ret;
> +
> +       ret = drm_simple_encoder_init(drm, &dsi->encoder,
> +                                     DRM_MODE_ENCODER_DSI);
> +       if (ret) {
> +               DRM_ERROR("Failed to encoder init to drm\n");
> +               return ret;
> +       }
> +
> +       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
> +
> +       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
> +                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> +       if (ret)
> +               goto err_cleanup_encoder;
> +
> +       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
> +       if (IS_ERR(dsi->connector)) {
> +               DRM_ERROR("Unable to create bridge connector\n");
> +               ret = PTR_ERR(dsi->connector);
> +               goto err_cleanup_encoder;
> +       }
> +       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
> +
> +       return 0;
> +
> +err_cleanup_encoder:
> +       drm_encoder_cleanup(&dsi->encoder);
> +       return ret;
> +}
> +
> +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> +{
> +       int ret;
> +       struct drm_device *drm = data;
> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> +
> +       ret = mtk_dsi_encoder_init(drm, dsi);
> +       if (ret)
> +               return ret;
> +
> +       return device_reset_optional(dev);
> +}
> +
> +static void mtk_dsi_unbind(struct device *dev, struct device *master,
> +                          void *data)
> +{
> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> +
> +       drm_encoder_cleanup(&dsi->encoder);
> +}
> +
> +static const struct component_ops mtk_dsi_component_ops = {
> +       .bind = mtk_dsi_bind,
> +       .unbind = mtk_dsi_unbind,
> +};
> +
>  static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
>                                struct mipi_dsi_device *device)
>  {
>         struct mtk_dsi *dsi = host_to_dsi(host);
> +       struct device *dev = host->dev;
> +       int ret;
>
>         dsi->lanes = device->lanes;
>         dsi->format = device->format;
>         dsi->mode_flags = device->mode_flags;
> +       dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
> +       if (IS_ERR(dsi->next_bridge))
> +               return PTR_ERR(dsi->next_bridge);
> +
> +       drm_bridge_add(&dsi->bridge);
> +
> +       ret = component_add(host->dev, &mtk_dsi_component_ops);
> +       if (ret) {
> +               DRM_ERROR("failed to add dsi_host component: %d\n", ret);
> +               drm_bridge_remove(&dsi->bridge);
> +               return ret;
> +       }
>
>         return 0;
>  }
>
> +static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
> +                              struct mipi_dsi_device *device)
> +{
> +       struct mtk_dsi *dsi = host_to_dsi(host);
> +
> +       component_del(host->dev, &mtk_dsi_component_ops);
> +       drm_bridge_remove(&dsi->bridge);
> +       return 0;
> +}
> +
>  static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
>  {
>         int ret;
> @@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>
>  static const struct mipi_dsi_host_ops mtk_dsi_ops = {
>         .attach = mtk_dsi_host_attach,
> +       .detach = mtk_dsi_host_detach,
>         .transfer = mtk_dsi_host_transfer,
>  };
>
> -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
> -{
> -       int ret;
> -
> -       ret = drm_simple_encoder_init(drm, &dsi->encoder,
> -                                     DRM_MODE_ENCODER_DSI);
> -       if (ret) {
> -               DRM_ERROR("Failed to encoder init to drm\n");
> -               return ret;
> -       }
> -
> -       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
> -
> -       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
> -                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> -       if (ret)
> -               goto err_cleanup_encoder;
> -
> -       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
> -       if (IS_ERR(dsi->connector)) {
> -               DRM_ERROR("Unable to create bridge connector\n");
> -               ret = PTR_ERR(dsi->connector);
> -               goto err_cleanup_encoder;
> -       }
> -       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
> -
> -       return 0;
> -
> -err_cleanup_encoder:
> -       drm_encoder_cleanup(&dsi->encoder);
> -       return ret;
> -}
> -
> -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> -{
> -       int ret;
> -       struct drm_device *drm = data;
> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> -
> -       ret = mtk_dsi_encoder_init(drm, dsi);
> -       if (ret)
> -               return ret;
> -
> -       return device_reset_optional(dev);
> -}
> -
> -static void mtk_dsi_unbind(struct device *dev, struct device *master,
> -                          void *data)
> -{
> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> -
> -       drm_encoder_cleanup(&dsi->encoder);
> -}
> -
> -static const struct component_ops mtk_dsi_component_ops = {
> -       .bind = mtk_dsi_bind,
> -       .unbind = mtk_dsi_unbind,
> -};
> -
>  static int mtk_dsi_probe(struct platform_device *pdev)
>  {
>         struct mtk_dsi *dsi;
>         struct device *dev = &pdev->dev;
> -       struct drm_panel *panel;
>         struct resource *regs;
>         int irq_num;
>         int ret;
> @@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>                 return ret;
>         }
>
> -       ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
> -                                         &panel, &dsi->next_bridge);
> -       if (ret)
> -               goto err_unregister_host;
> -
> -       if (panel) {
> -               dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
> -               if (IS_ERR(dsi->next_bridge)) {
> -                       ret = PTR_ERR(dsi->next_bridge);
> -                       goto err_unregister_host;
> -               }
> -       }
> -
>         dsi->driver_data = of_device_get_match_data(dev);
>
>         dsi->engine_clk = devm_clk_get(dev, "engine");
> @@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>         dsi->bridge.of_node = dev->of_node;
>         dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
>
> -       drm_bridge_add(&dsi->bridge);
> -
> -       ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
> -       if (ret) {
> -               dev_err(&pdev->dev, "failed to add component: %d\n", ret);
> -               goto err_unregister_host;
> -       }
> -
>         return 0;
>
>  err_unregister_host:
> @@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
>         struct mtk_dsi *dsi = platform_get_drvdata(pdev);
>
>         mtk_output_dsi_disable(dsi);
> -       drm_bridge_remove(&dsi->bridge);
> -       component_del(&pdev->dev, &mtk_dsi_component_ops);
>         mipi_dsi_host_unregister(&dsi->host);
>
>         return 0;
> --
> 2.33.1
>

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[Chun-Kuang Hu]

Hi, Angelo:

AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
2022年1月27日 週四 下午10:36寫道：
>
> DRM bridge drivers are now attaching their DSI device at probe time,
> which requires us to register our DSI host in order to let the bridge
> to probe: this recently started producing an endless -EPROBE_DEFER
> loop on some machines that are using external bridges, like the
> parade-ps8640, found on the ACER Chromebook R13.
>
> Now that the DSI hosts/devices probe sequence is documented, we can
> do adjustments to the mtk_dsi driver as to both fix now and make sure
> to avoid this situation in the future: for this, following what is
> documented in drm_bridge.c, move the mtk_dsi component_add() to the
> mtk_dsi_ops.attach callback and delete it in the detach callback;
> keeping in mind that we are registering a drm_bridge for our DSI,
> which is only used/attached if the DSI Host is bound, it wouldn't
> make sense to keep adding our bridge at probe time (as it would
> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
> that one to the dsi host attach function (and remove it in detach).
>
> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")

The fixed tag should indicate the patch which cause the bug, but why a
patch just adding document would cause bug?
So no any patch cause bug? This patch just want to prevent a possible bug?

Regards,
Chun-Kuang.

> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>  1 file changed, 84 insertions(+), 83 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 5d90d2eb0019..bced4c7d668e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
>         mtk_dsi_poweroff(dsi);
>  }
>
> +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
> +{
> +       int ret;
> +
> +       ret = drm_simple_encoder_init(drm, &dsi->encoder,
> +                                     DRM_MODE_ENCODER_DSI);
> +       if (ret) {
> +               DRM_ERROR("Failed to encoder init to drm\n");
> +               return ret;
> +       }
> +
> +       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
> +
> +       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
> +                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> +       if (ret)
> +               goto err_cleanup_encoder;
> +
> +       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
> +       if (IS_ERR(dsi->connector)) {
> +               DRM_ERROR("Unable to create bridge connector\n");
> +               ret = PTR_ERR(dsi->connector);
> +               goto err_cleanup_encoder;
> +       }
> +       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
> +
> +       return 0;
> +
> +err_cleanup_encoder:
> +       drm_encoder_cleanup(&dsi->encoder);
> +       return ret;
> +}
> +
> +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> +{
> +       int ret;
> +       struct drm_device *drm = data;
> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> +
> +       ret = mtk_dsi_encoder_init(drm, dsi);
> +       if (ret)
> +               return ret;
> +
> +       return device_reset_optional(dev);
> +}
> +
> +static void mtk_dsi_unbind(struct device *dev, struct device *master,
> +                          void *data)
> +{
> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> +
> +       drm_encoder_cleanup(&dsi->encoder);
> +}
> +
> +static const struct component_ops mtk_dsi_component_ops = {
> +       .bind = mtk_dsi_bind,
> +       .unbind = mtk_dsi_unbind,
> +};
> +
>  static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
>                                struct mipi_dsi_device *device)
>  {
>         struct mtk_dsi *dsi = host_to_dsi(host);
> +       struct device *dev = host->dev;
> +       int ret;
>
>         dsi->lanes = device->lanes;
>         dsi->format = device->format;
>         dsi->mode_flags = device->mode_flags;
> +       dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
> +       if (IS_ERR(dsi->next_bridge))
> +               return PTR_ERR(dsi->next_bridge);
> +
> +       drm_bridge_add(&dsi->bridge);
> +
> +       ret = component_add(host->dev, &mtk_dsi_component_ops);
> +       if (ret) {
> +               DRM_ERROR("failed to add dsi_host component: %d\n", ret);
> +               drm_bridge_remove(&dsi->bridge);
> +               return ret;
> +       }
>
>         return 0;
>  }
>
> +static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
> +                              struct mipi_dsi_device *device)
> +{
> +       struct mtk_dsi *dsi = host_to_dsi(host);
> +
> +       component_del(host->dev, &mtk_dsi_component_ops);
> +       drm_bridge_remove(&dsi->bridge);
> +       return 0;
> +}
> +
>  static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
>  {
>         int ret;
> @@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>
>  static const struct mipi_dsi_host_ops mtk_dsi_ops = {
>         .attach = mtk_dsi_host_attach,
> +       .detach = mtk_dsi_host_detach,
>         .transfer = mtk_dsi_host_transfer,
>  };
>
> -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
> -{
> -       int ret;
> -
> -       ret = drm_simple_encoder_init(drm, &dsi->encoder,
> -                                     DRM_MODE_ENCODER_DSI);
> -       if (ret) {
> -               DRM_ERROR("Failed to encoder init to drm\n");
> -               return ret;
> -       }
> -
> -       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
> -
> -       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
> -                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> -       if (ret)
> -               goto err_cleanup_encoder;
> -
> -       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
> -       if (IS_ERR(dsi->connector)) {
> -               DRM_ERROR("Unable to create bridge connector\n");
> -               ret = PTR_ERR(dsi->connector);
> -               goto err_cleanup_encoder;
> -       }
> -       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
> -
> -       return 0;
> -
> -err_cleanup_encoder:
> -       drm_encoder_cleanup(&dsi->encoder);
> -       return ret;
> -}
> -
> -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> -{
> -       int ret;
> -       struct drm_device *drm = data;
> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> -
> -       ret = mtk_dsi_encoder_init(drm, dsi);
> -       if (ret)
> -               return ret;
> -
> -       return device_reset_optional(dev);
> -}
> -
> -static void mtk_dsi_unbind(struct device *dev, struct device *master,
> -                          void *data)
> -{
> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> -
> -       drm_encoder_cleanup(&dsi->encoder);
> -}
> -
> -static const struct component_ops mtk_dsi_component_ops = {
> -       .bind = mtk_dsi_bind,
> -       .unbind = mtk_dsi_unbind,
> -};
> -
>  static int mtk_dsi_probe(struct platform_device *pdev)
>  {
>         struct mtk_dsi *dsi;
>         struct device *dev = &pdev->dev;
> -       struct drm_panel *panel;
>         struct resource *regs;
>         int irq_num;
>         int ret;
> @@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>                 return ret;
>         }
>
> -       ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
> -                                         &panel, &dsi->next_bridge);
> -       if (ret)
> -               goto err_unregister_host;
> -
> -       if (panel) {
> -               dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
> -               if (IS_ERR(dsi->next_bridge)) {
> -                       ret = PTR_ERR(dsi->next_bridge);
> -                       goto err_unregister_host;
> -               }
> -       }
> -
>         dsi->driver_data = of_device_get_match_data(dev);
>
>         dsi->engine_clk = devm_clk_get(dev, "engine");
> @@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>         dsi->bridge.of_node = dev->of_node;
>         dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
>
> -       drm_bridge_add(&dsi->bridge);
> -
> -       ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
> -       if (ret) {
> -               dev_err(&pdev->dev, "failed to add component: %d\n", ret);
> -               goto err_unregister_host;
> -       }
> -
>         return 0;
>
>  err_unregister_host:
> @@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
>         struct mtk_dsi *dsi = platform_get_drvdata(pdev);
>
>         mtk_output_dsi_disable(dsi);
> -       drm_bridge_remove(&dsi->bridge);
> -       component_del(&pdev->dev, &mtk_dsi_component_ops);
>         mipi_dsi_host_unregister(&dsi->host);
>
>         return 0;
> --
> 2.33.1
>

_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[Chun-Kuang Hu]

Hi, Angelo:

AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
2022年1月27日 週四 下午10:36寫道：
>
> DRM bridge drivers are now attaching their DSI device at probe time,
> which requires us to register our DSI host in order to let the bridge
> to probe: this recently started producing an endless -EPROBE_DEFER
> loop on some machines that are using external bridges, like the
> parade-ps8640, found on the ACER Chromebook R13.
>
> Now that the DSI hosts/devices probe sequence is documented, we can
> do adjustments to the mtk_dsi driver as to both fix now and make sure
> to avoid this situation in the future: for this, following what is
> documented in drm_bridge.c, move the mtk_dsi component_add() to the
> mtk_dsi_ops.attach callback and delete it in the detach callback;
> keeping in mind that we are registering a drm_bridge for our DSI,
> which is only used/attached if the DSI Host is bound, it wouldn't
> make sense to keep adding our bridge at probe time (as it would
> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
> that one to the dsi host attach function (and remove it in detach).
>
> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")

The fixed tag should indicate the patch which cause the bug, but why a
patch just adding document would cause bug?
So no any patch cause bug? This patch just want to prevent a possible bug?

Regards,
Chun-Kuang.

> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>  1 file changed, 84 insertions(+), 83 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 5d90d2eb0019..bced4c7d668e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
>         mtk_dsi_poweroff(dsi);
>  }
>
> +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
> +{
> +       int ret;
> +
> +       ret = drm_simple_encoder_init(drm, &dsi->encoder,
> +                                     DRM_MODE_ENCODER_DSI);
> +       if (ret) {
> +               DRM_ERROR("Failed to encoder init to drm\n");
> +               return ret;
> +       }
> +
> +       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
> +
> +       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
> +                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> +       if (ret)
> +               goto err_cleanup_encoder;
> +
> +       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
> +       if (IS_ERR(dsi->connector)) {
> +               DRM_ERROR("Unable to create bridge connector\n");
> +               ret = PTR_ERR(dsi->connector);
> +               goto err_cleanup_encoder;
> +       }
> +       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
> +
> +       return 0;
> +
> +err_cleanup_encoder:
> +       drm_encoder_cleanup(&dsi->encoder);
> +       return ret;
> +}
> +
> +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> +{
> +       int ret;
> +       struct drm_device *drm = data;
> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> +
> +       ret = mtk_dsi_encoder_init(drm, dsi);
> +       if (ret)
> +               return ret;
> +
> +       return device_reset_optional(dev);
> +}
> +
> +static void mtk_dsi_unbind(struct device *dev, struct device *master,
> +                          void *data)
> +{
> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> +
> +       drm_encoder_cleanup(&dsi->encoder);
> +}
> +
> +static const struct component_ops mtk_dsi_component_ops = {
> +       .bind = mtk_dsi_bind,
> +       .unbind = mtk_dsi_unbind,
> +};
> +
>  static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
>                                struct mipi_dsi_device *device)
>  {
>         struct mtk_dsi *dsi = host_to_dsi(host);
> +       struct device *dev = host->dev;
> +       int ret;
>
>         dsi->lanes = device->lanes;
>         dsi->format = device->format;
>         dsi->mode_flags = device->mode_flags;
> +       dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
> +       if (IS_ERR(dsi->next_bridge))
> +               return PTR_ERR(dsi->next_bridge);
> +
> +       drm_bridge_add(&dsi->bridge);
> +
> +       ret = component_add(host->dev, &mtk_dsi_component_ops);
> +       if (ret) {
> +               DRM_ERROR("failed to add dsi_host component: %d\n", ret);
> +               drm_bridge_remove(&dsi->bridge);
> +               return ret;
> +       }
>
>         return 0;
>  }
>
> +static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
> +                              struct mipi_dsi_device *device)
> +{
> +       struct mtk_dsi *dsi = host_to_dsi(host);
> +
> +       component_del(host->dev, &mtk_dsi_component_ops);
> +       drm_bridge_remove(&dsi->bridge);
> +       return 0;
> +}
> +
>  static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
>  {
>         int ret;
> @@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>
>  static const struct mipi_dsi_host_ops mtk_dsi_ops = {
>         .attach = mtk_dsi_host_attach,
> +       .detach = mtk_dsi_host_detach,
>         .transfer = mtk_dsi_host_transfer,
>  };
>
> -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
> -{
> -       int ret;
> -
> -       ret = drm_simple_encoder_init(drm, &dsi->encoder,
> -                                     DRM_MODE_ENCODER_DSI);
> -       if (ret) {
> -               DRM_ERROR("Failed to encoder init to drm\n");
> -               return ret;
> -       }
> -
> -       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
> -
> -       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
> -                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> -       if (ret)
> -               goto err_cleanup_encoder;
> -
> -       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
> -       if (IS_ERR(dsi->connector)) {
> -               DRM_ERROR("Unable to create bridge connector\n");
> -               ret = PTR_ERR(dsi->connector);
> -               goto err_cleanup_encoder;
> -       }
> -       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
> -
> -       return 0;
> -
> -err_cleanup_encoder:
> -       drm_encoder_cleanup(&dsi->encoder);
> -       return ret;
> -}
> -
> -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> -{
> -       int ret;
> -       struct drm_device *drm = data;
> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> -
> -       ret = mtk_dsi_encoder_init(drm, dsi);
> -       if (ret)
> -               return ret;
> -
> -       return device_reset_optional(dev);
> -}
> -
> -static void mtk_dsi_unbind(struct device *dev, struct device *master,
> -                          void *data)
> -{
> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> -
> -       drm_encoder_cleanup(&dsi->encoder);
> -}
> -
> -static const struct component_ops mtk_dsi_component_ops = {
> -       .bind = mtk_dsi_bind,
> -       .unbind = mtk_dsi_unbind,
> -};
> -
>  static int mtk_dsi_probe(struct platform_device *pdev)
>  {
>         struct mtk_dsi *dsi;
>         struct device *dev = &pdev->dev;
> -       struct drm_panel *panel;
>         struct resource *regs;
>         int irq_num;
>         int ret;
> @@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>                 return ret;
>         }
>
> -       ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
> -                                         &panel, &dsi->next_bridge);
> -       if (ret)
> -               goto err_unregister_host;
> -
> -       if (panel) {
> -               dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
> -               if (IS_ERR(dsi->next_bridge)) {
> -                       ret = PTR_ERR(dsi->next_bridge);
> -                       goto err_unregister_host;
> -               }
> -       }
> -
>         dsi->driver_data = of_device_get_match_data(dev);
>
>         dsi->engine_clk = devm_clk_get(dev, "engine");
> @@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>         dsi->bridge.of_node = dev->of_node;
>         dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
>
> -       drm_bridge_add(&dsi->bridge);
> -
> -       ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
> -       if (ret) {
> -               dev_err(&pdev->dev, "failed to add component: %d\n", ret);
> -               goto err_unregister_host;
> -       }
> -
>         return 0;
>
>  err_unregister_host:
> @@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
>         struct mtk_dsi *dsi = platform_get_drvdata(pdev);
>
>         mtk_output_dsi_disable(dsi);
> -       drm_bridge_remove(&dsi->bridge);
> -       component_del(&pdev->dev, &mtk_dsi_component_ops);
>         mipi_dsi_host_unregister(&dsi->host);
>
>         return 0;
> --
> 2.33.1
>

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[Chun-Kuang Hu]

Hi, Angelo:

AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
2022年1月27日 週四 下午10:36寫道：
>
> DRM bridge drivers are now attaching their DSI device at probe time,
> which requires us to register our DSI host in order to let the bridge
> to probe: this recently started producing an endless -EPROBE_DEFER
> loop on some machines that are using external bridges, like the
> parade-ps8640, found on the ACER Chromebook R13.
>
> Now that the DSI hosts/devices probe sequence is documented, we can
> do adjustments to the mtk_dsi driver as to both fix now and make sure
> to avoid this situation in the future: for this, following what is
> documented in drm_bridge.c, move the mtk_dsi component_add() to the
> mtk_dsi_ops.attach callback and delete it in the detach callback;
> keeping in mind that we are registering a drm_bridge for our DSI,
> which is only used/attached if the DSI Host is bound, it wouldn't
> make sense to keep adding our bridge at probe time (as it would
> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
> that one to the dsi host attach function (and remove it in detach).
>
> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")

The fixed tag should indicate the patch which cause the bug, but why a
patch just adding document would cause bug?
So no any patch cause bug? This patch just want to prevent a possible bug?

Regards,
Chun-Kuang.

> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>
> ---
>  drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>  1 file changed, 84 insertions(+), 83 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
> index 5d90d2eb0019..bced4c7d668e 100644
> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
> @@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
>         mtk_dsi_poweroff(dsi);
>  }
>
> +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
> +{
> +       int ret;
> +
> +       ret = drm_simple_encoder_init(drm, &dsi->encoder,
> +                                     DRM_MODE_ENCODER_DSI);
> +       if (ret) {
> +               DRM_ERROR("Failed to encoder init to drm\n");
> +               return ret;
> +       }
> +
> +       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
> +
> +       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
> +                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> +       if (ret)
> +               goto err_cleanup_encoder;
> +
> +       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
> +       if (IS_ERR(dsi->connector)) {
> +               DRM_ERROR("Unable to create bridge connector\n");
> +               ret = PTR_ERR(dsi->connector);
> +               goto err_cleanup_encoder;
> +       }
> +       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
> +
> +       return 0;
> +
> +err_cleanup_encoder:
> +       drm_encoder_cleanup(&dsi->encoder);
> +       return ret;
> +}
> +
> +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> +{
> +       int ret;
> +       struct drm_device *drm = data;
> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> +
> +       ret = mtk_dsi_encoder_init(drm, dsi);
> +       if (ret)
> +               return ret;
> +
> +       return device_reset_optional(dev);
> +}
> +
> +static void mtk_dsi_unbind(struct device *dev, struct device *master,
> +                          void *data)
> +{
> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> +
> +       drm_encoder_cleanup(&dsi->encoder);
> +}
> +
> +static const struct component_ops mtk_dsi_component_ops = {
> +       .bind = mtk_dsi_bind,
> +       .unbind = mtk_dsi_unbind,
> +};
> +
>  static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
>                                struct mipi_dsi_device *device)
>  {
>         struct mtk_dsi *dsi = host_to_dsi(host);
> +       struct device *dev = host->dev;
> +       int ret;
>
>         dsi->lanes = device->lanes;
>         dsi->format = device->format;
>         dsi->mode_flags = device->mode_flags;
> +       dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
> +       if (IS_ERR(dsi->next_bridge))
> +               return PTR_ERR(dsi->next_bridge);
> +
> +       drm_bridge_add(&dsi->bridge);
> +
> +       ret = component_add(host->dev, &mtk_dsi_component_ops);
> +       if (ret) {
> +               DRM_ERROR("failed to add dsi_host component: %d\n", ret);
> +               drm_bridge_remove(&dsi->bridge);
> +               return ret;
> +       }
>
>         return 0;
>  }
>
> +static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
> +                              struct mipi_dsi_device *device)
> +{
> +       struct mtk_dsi *dsi = host_to_dsi(host);
> +
> +       component_del(host->dev, &mtk_dsi_component_ops);
> +       drm_bridge_remove(&dsi->bridge);
> +       return 0;
> +}
> +
>  static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
>  {
>         int ret;
> @@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>
>  static const struct mipi_dsi_host_ops mtk_dsi_ops = {
>         .attach = mtk_dsi_host_attach,
> +       .detach = mtk_dsi_host_detach,
>         .transfer = mtk_dsi_host_transfer,
>  };
>
> -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
> -{
> -       int ret;
> -
> -       ret = drm_simple_encoder_init(drm, &dsi->encoder,
> -                                     DRM_MODE_ENCODER_DSI);
> -       if (ret) {
> -               DRM_ERROR("Failed to encoder init to drm\n");
> -               return ret;
> -       }
> -
> -       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
> -
> -       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
> -                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> -       if (ret)
> -               goto err_cleanup_encoder;
> -
> -       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
> -       if (IS_ERR(dsi->connector)) {
> -               DRM_ERROR("Unable to create bridge connector\n");
> -               ret = PTR_ERR(dsi->connector);
> -               goto err_cleanup_encoder;
> -       }
> -       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
> -
> -       return 0;
> -
> -err_cleanup_encoder:
> -       drm_encoder_cleanup(&dsi->encoder);
> -       return ret;
> -}
> -
> -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
> -{
> -       int ret;
> -       struct drm_device *drm = data;
> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> -
> -       ret = mtk_dsi_encoder_init(drm, dsi);
> -       if (ret)
> -               return ret;
> -
> -       return device_reset_optional(dev);
> -}
> -
> -static void mtk_dsi_unbind(struct device *dev, struct device *master,
> -                          void *data)
> -{
> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
> -
> -       drm_encoder_cleanup(&dsi->encoder);
> -}
> -
> -static const struct component_ops mtk_dsi_component_ops = {
> -       .bind = mtk_dsi_bind,
> -       .unbind = mtk_dsi_unbind,
> -};
> -
>  static int mtk_dsi_probe(struct platform_device *pdev)
>  {
>         struct mtk_dsi *dsi;
>         struct device *dev = &pdev->dev;
> -       struct drm_panel *panel;
>         struct resource *regs;
>         int irq_num;
>         int ret;
> @@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>                 return ret;
>         }
>
> -       ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
> -                                         &panel, &dsi->next_bridge);
> -       if (ret)
> -               goto err_unregister_host;
> -
> -       if (panel) {
> -               dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
> -               if (IS_ERR(dsi->next_bridge)) {
> -                       ret = PTR_ERR(dsi->next_bridge);
> -                       goto err_unregister_host;
> -               }
> -       }
> -
>         dsi->driver_data = of_device_get_match_data(dev);
>
>         dsi->engine_clk = devm_clk_get(dev, "engine");
> @@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>         dsi->bridge.of_node = dev->of_node;
>         dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
>
> -       drm_bridge_add(&dsi->bridge);
> -
> -       ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
> -       if (ret) {
> -               dev_err(&pdev->dev, "failed to add component: %d\n", ret);
> -               goto err_unregister_host;
> -       }
> -
>         return 0;
>
>  err_unregister_host:
> @@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
>         struct mtk_dsi *dsi = platform_get_drvdata(pdev);
>
>         mtk_output_dsi_disable(dsi);
> -       drm_bridge_remove(&dsi->bridge);
> -       component_del(&pdev->dev, &mtk_dsi_component_ops);
>         mipi_dsi_host_unregister(&dsi->host);
>
>         return 0;
> --
> 2.33.1
>

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
> Hi, Angelo:
> 
> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
> 2022年1月27日 週四 下午10:36寫道：
>>
>> DRM bridge drivers are now attaching their DSI device at probe time,
>> which requires us to register our DSI host in order to let the bridge
>> to probe: this recently started producing an endless -EPROBE_DEFER
>> loop on some machines that are using external bridges, like the
>> parade-ps8640, found on the ACER Chromebook R13.
>>
>> Now that the DSI hosts/devices probe sequence is documented, we can
>> do adjustments to the mtk_dsi driver as to both fix now and make sure
>> to avoid this situation in the future: for this, following what is
>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
>> mtk_dsi_ops.attach callback and delete it in the detach callback;
>> keeping in mind that we are registering a drm_bridge for our DSI,
>> which is only used/attached if the DSI Host is bound, it wouldn't
>> make sense to keep adding our bridge at probe time (as it would
>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
>> that one to the dsi host attach function (and remove it in detach).
>>
>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
> 
> The fixed tag should indicate the patch which cause the bug, but why a
> patch just adding document would cause bug?
> So no any patch cause bug? This patch just want to prevent a possible bug?
> 

I think you've missed my previous message on v2, so I will paste it here:

unfortunately I couldn't find a valid commit for a Fixes tag. This
started being an issue at some point, when the DRM was changed to
adhere to the documented probe sequence: the MediaTek DSI driver was
not the only one that got broken/affected by these changes.

If you have any advice on which commit should be tagged, I'm open for
any kind of suggestion.


I tried to check on other drivers which got fixed for the same behavior,
for example drm/msm, but none of them had a Fixes tag.
When the DRM got changed to adhere to this sequence, some drm/bridge
drivers were also changed; this has created some incompatibilities with
some drm drivers, including drm/msm and drm/mediatek.

This commit is not fixing a latent bug that was introduced in drm/mediatek
but rather one that was induced by the new, fixed, probe flow that got
recently documented - and to which drivers should adhere; failing to adhere
to that will produce an endless -EPROBE_DEFER loop, due to other drivers
(as mentioned, for example drm/bridge drivers) having been changed to use
that probe sequence.


Regards,
Angelo

> Regards,
> Chun-Kuang.
> 
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>>
>> ---
>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>>   1 file changed, 84 insertions(+), 83 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> index 5d90d2eb0019..bced4c7d668e 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> @@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
>>          mtk_dsi_poweroff(dsi);
>>   }
>>
>> +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
>> +{
>> +       int ret;
>> +
>> +       ret = drm_simple_encoder_init(drm, &dsi->encoder,
>> +                                     DRM_MODE_ENCODER_DSI);
>> +       if (ret) {
>> +               DRM_ERROR("Failed to encoder init to drm\n");
>> +               return ret;
>> +       }
>> +
>> +       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
>> +
>> +       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
>> +                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>> +       if (ret)
>> +               goto err_cleanup_encoder;
>> +
>> +       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
>> +       if (IS_ERR(dsi->connector)) {
>> +               DRM_ERROR("Unable to create bridge connector\n");
>> +               ret = PTR_ERR(dsi->connector);
>> +               goto err_cleanup_encoder;
>> +       }
>> +       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
>> +
>> +       return 0;
>> +
>> +err_cleanup_encoder:
>> +       drm_encoder_cleanup(&dsi->encoder);
>> +       return ret;
>> +}
>> +
>> +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
>> +{
>> +       int ret;
>> +       struct drm_device *drm = data;
>> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> +
>> +       ret = mtk_dsi_encoder_init(drm, dsi);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return device_reset_optional(dev);
>> +}
>> +
>> +static void mtk_dsi_unbind(struct device *dev, struct device *master,
>> +                          void *data)
>> +{
>> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> +
>> +       drm_encoder_cleanup(&dsi->encoder);
>> +}
>> +
>> +static const struct component_ops mtk_dsi_component_ops = {
>> +       .bind = mtk_dsi_bind,
>> +       .unbind = mtk_dsi_unbind,
>> +};
>> +
>>   static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
>>                                 struct mipi_dsi_device *device)
>>   {
>>          struct mtk_dsi *dsi = host_to_dsi(host);
>> +       struct device *dev = host->dev;
>> +       int ret;
>>
>>          dsi->lanes = device->lanes;
>>          dsi->format = device->format;
>>          dsi->mode_flags = device->mode_flags;
>> +       dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
>> +       if (IS_ERR(dsi->next_bridge))
>> +               return PTR_ERR(dsi->next_bridge);
>> +
>> +       drm_bridge_add(&dsi->bridge);
>> +
>> +       ret = component_add(host->dev, &mtk_dsi_component_ops);
>> +       if (ret) {
>> +               DRM_ERROR("failed to add dsi_host component: %d\n", ret);
>> +               drm_bridge_remove(&dsi->bridge);
>> +               return ret;
>> +       }
>>
>>          return 0;
>>   }
>>
>> +static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
>> +                              struct mipi_dsi_device *device)
>> +{
>> +       struct mtk_dsi *dsi = host_to_dsi(host);
>> +
>> +       component_del(host->dev, &mtk_dsi_component_ops);
>> +       drm_bridge_remove(&dsi->bridge);
>> +       return 0;
>> +}
>> +
>>   static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
>>   {
>>          int ret;
>> @@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>>
>>   static const struct mipi_dsi_host_ops mtk_dsi_ops = {
>>          .attach = mtk_dsi_host_attach,
>> +       .detach = mtk_dsi_host_detach,
>>          .transfer = mtk_dsi_host_transfer,
>>   };
>>
>> -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
>> -{
>> -       int ret;
>> -
>> -       ret = drm_simple_encoder_init(drm, &dsi->encoder,
>> -                                     DRM_MODE_ENCODER_DSI);
>> -       if (ret) {
>> -               DRM_ERROR("Failed to encoder init to drm\n");
>> -               return ret;
>> -       }
>> -
>> -       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
>> -
>> -       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
>> -                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>> -       if (ret)
>> -               goto err_cleanup_encoder;
>> -
>> -       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
>> -       if (IS_ERR(dsi->connector)) {
>> -               DRM_ERROR("Unable to create bridge connector\n");
>> -               ret = PTR_ERR(dsi->connector);
>> -               goto err_cleanup_encoder;
>> -       }
>> -       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
>> -
>> -       return 0;
>> -
>> -err_cleanup_encoder:
>> -       drm_encoder_cleanup(&dsi->encoder);
>> -       return ret;
>> -}
>> -
>> -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
>> -{
>> -       int ret;
>> -       struct drm_device *drm = data;
>> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> -
>> -       ret = mtk_dsi_encoder_init(drm, dsi);
>> -       if (ret)
>> -               return ret;
>> -
>> -       return device_reset_optional(dev);
>> -}
>> -
>> -static void mtk_dsi_unbind(struct device *dev, struct device *master,
>> -                          void *data)
>> -{
>> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> -
>> -       drm_encoder_cleanup(&dsi->encoder);
>> -}
>> -
>> -static const struct component_ops mtk_dsi_component_ops = {
>> -       .bind = mtk_dsi_bind,
>> -       .unbind = mtk_dsi_unbind,
>> -};
>> -
>>   static int mtk_dsi_probe(struct platform_device *pdev)
>>   {
>>          struct mtk_dsi *dsi;
>>          struct device *dev = &pdev->dev;
>> -       struct drm_panel *panel;
>>          struct resource *regs;
>>          int irq_num;
>>          int ret;
>> @@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>                  return ret;
>>          }
>>
>> -       ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
>> -                                         &panel, &dsi->next_bridge);
>> -       if (ret)
>> -               goto err_unregister_host;
>> -
>> -       if (panel) {
>> -               dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
>> -               if (IS_ERR(dsi->next_bridge)) {
>> -                       ret = PTR_ERR(dsi->next_bridge);
>> -                       goto err_unregister_host;
>> -               }
>> -       }
>> -
>>          dsi->driver_data = of_device_get_match_data(dev);
>>
>>          dsi->engine_clk = devm_clk_get(dev, "engine");
>> @@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>          dsi->bridge.of_node = dev->of_node;
>>          dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
>>
>> -       drm_bridge_add(&dsi->bridge);
>> -
>> -       ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
>> -       if (ret) {
>> -               dev_err(&pdev->dev, "failed to add component: %d\n", ret);
>> -               goto err_unregister_host;
>> -       }
>> -
>>          return 0;
>>
>>   err_unregister_host:
>> @@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
>>          struct mtk_dsi *dsi = platform_get_drvdata(pdev);
>>
>>          mtk_output_dsi_disable(dsi);
>> -       drm_bridge_remove(&dsi->bridge);
>> -       component_del(&pdev->dev, &mtk_dsi_component_ops);
>>          mipi_dsi_host_unregister(&dsi->host);
>>
>>          return 0;
>> --
>> 2.33.1
>>


-- 
AngeloGioacchino Del Regno
Software Engineer

Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
Registered in England & Wales, no. 5513718

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
> Hi, Angelo:
> 
> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
> 2022年1月27日 週四 下午10:36寫道：
>>
>> DRM bridge drivers are now attaching their DSI device at probe time,
>> which requires us to register our DSI host in order to let the bridge
>> to probe: this recently started producing an endless -EPROBE_DEFER
>> loop on some machines that are using external bridges, like the
>> parade-ps8640, found on the ACER Chromebook R13.
>>
>> Now that the DSI hosts/devices probe sequence is documented, we can
>> do adjustments to the mtk_dsi driver as to both fix now and make sure
>> to avoid this situation in the future: for this, following what is
>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
>> mtk_dsi_ops.attach callback and delete it in the detach callback;
>> keeping in mind that we are registering a drm_bridge for our DSI,
>> which is only used/attached if the DSI Host is bound, it wouldn't
>> make sense to keep adding our bridge at probe time (as it would
>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
>> that one to the dsi host attach function (and remove it in detach).
>>
>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
> 
> The fixed tag should indicate the patch which cause the bug, but why a
> patch just adding document would cause bug?
> So no any patch cause bug? This patch just want to prevent a possible bug?
> 

I think you've missed my previous message on v2, so I will paste it here:

unfortunately I couldn't find a valid commit for a Fixes tag. This
started being an issue at some point, when the DRM was changed to
adhere to the documented probe sequence: the MediaTek DSI driver was
not the only one that got broken/affected by these changes.

If you have any advice on which commit should be tagged, I'm open for
any kind of suggestion.


I tried to check on other drivers which got fixed for the same behavior,
for example drm/msm, but none of them had a Fixes tag.
When the DRM got changed to adhere to this sequence, some drm/bridge
drivers were also changed; this has created some incompatibilities with
some drm drivers, including drm/msm and drm/mediatek.

This commit is not fixing a latent bug that was introduced in drm/mediatek
but rather one that was induced by the new, fixed, probe flow that got
recently documented - and to which drivers should adhere; failing to adhere
to that will produce an endless -EPROBE_DEFER loop, due to other drivers
(as mentioned, for example drm/bridge drivers) having been changed to use
that probe sequence.


Regards,
Angelo

> Regards,
> Chun-Kuang.
> 
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>>
>> ---
>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>>   1 file changed, 84 insertions(+), 83 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> index 5d90d2eb0019..bced4c7d668e 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> @@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
>>          mtk_dsi_poweroff(dsi);
>>   }
>>
>> +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
>> +{
>> +       int ret;
>> +
>> +       ret = drm_simple_encoder_init(drm, &dsi->encoder,
>> +                                     DRM_MODE_ENCODER_DSI);
>> +       if (ret) {
>> +               DRM_ERROR("Failed to encoder init to drm\n");
>> +               return ret;
>> +       }
>> +
>> +       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
>> +
>> +       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
>> +                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>> +       if (ret)
>> +               goto err_cleanup_encoder;
>> +
>> +       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
>> +       if (IS_ERR(dsi->connector)) {
>> +               DRM_ERROR("Unable to create bridge connector\n");
>> +               ret = PTR_ERR(dsi->connector);
>> +               goto err_cleanup_encoder;
>> +       }
>> +       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
>> +
>> +       return 0;
>> +
>> +err_cleanup_encoder:
>> +       drm_encoder_cleanup(&dsi->encoder);
>> +       return ret;
>> +}
>> +
>> +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
>> +{
>> +       int ret;
>> +       struct drm_device *drm = data;
>> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> +
>> +       ret = mtk_dsi_encoder_init(drm, dsi);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return device_reset_optional(dev);
>> +}
>> +
>> +static void mtk_dsi_unbind(struct device *dev, struct device *master,
>> +                          void *data)
>> +{
>> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> +
>> +       drm_encoder_cleanup(&dsi->encoder);
>> +}
>> +
>> +static const struct component_ops mtk_dsi_component_ops = {
>> +       .bind = mtk_dsi_bind,
>> +       .unbind = mtk_dsi_unbind,
>> +};
>> +
>>   static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
>>                                 struct mipi_dsi_device *device)
>>   {
>>          struct mtk_dsi *dsi = host_to_dsi(host);
>> +       struct device *dev = host->dev;
>> +       int ret;
>>
>>          dsi->lanes = device->lanes;
>>          dsi->format = device->format;
>>          dsi->mode_flags = device->mode_flags;
>> +       dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
>> +       if (IS_ERR(dsi->next_bridge))
>> +               return PTR_ERR(dsi->next_bridge);
>> +
>> +       drm_bridge_add(&dsi->bridge);
>> +
>> +       ret = component_add(host->dev, &mtk_dsi_component_ops);
>> +       if (ret) {
>> +               DRM_ERROR("failed to add dsi_host component: %d\n", ret);
>> +               drm_bridge_remove(&dsi->bridge);
>> +               return ret;
>> +       }
>>
>>          return 0;
>>   }
>>
>> +static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
>> +                              struct mipi_dsi_device *device)
>> +{
>> +       struct mtk_dsi *dsi = host_to_dsi(host);
>> +
>> +       component_del(host->dev, &mtk_dsi_component_ops);
>> +       drm_bridge_remove(&dsi->bridge);
>> +       return 0;
>> +}
>> +
>>   static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
>>   {
>>          int ret;
>> @@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>>
>>   static const struct mipi_dsi_host_ops mtk_dsi_ops = {
>>          .attach = mtk_dsi_host_attach,
>> +       .detach = mtk_dsi_host_detach,
>>          .transfer = mtk_dsi_host_transfer,
>>   };
>>
>> -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
>> -{
>> -       int ret;
>> -
>> -       ret = drm_simple_encoder_init(drm, &dsi->encoder,
>> -                                     DRM_MODE_ENCODER_DSI);
>> -       if (ret) {
>> -               DRM_ERROR("Failed to encoder init to drm\n");
>> -               return ret;
>> -       }
>> -
>> -       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
>> -
>> -       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
>> -                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>> -       if (ret)
>> -               goto err_cleanup_encoder;
>> -
>> -       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
>> -       if (IS_ERR(dsi->connector)) {
>> -               DRM_ERROR("Unable to create bridge connector\n");
>> -               ret = PTR_ERR(dsi->connector);
>> -               goto err_cleanup_encoder;
>> -       }
>> -       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
>> -
>> -       return 0;
>> -
>> -err_cleanup_encoder:
>> -       drm_encoder_cleanup(&dsi->encoder);
>> -       return ret;
>> -}
>> -
>> -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
>> -{
>> -       int ret;
>> -       struct drm_device *drm = data;
>> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> -
>> -       ret = mtk_dsi_encoder_init(drm, dsi);
>> -       if (ret)
>> -               return ret;
>> -
>> -       return device_reset_optional(dev);
>> -}
>> -
>> -static void mtk_dsi_unbind(struct device *dev, struct device *master,
>> -                          void *data)
>> -{
>> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> -
>> -       drm_encoder_cleanup(&dsi->encoder);
>> -}
>> -
>> -static const struct component_ops mtk_dsi_component_ops = {
>> -       .bind = mtk_dsi_bind,
>> -       .unbind = mtk_dsi_unbind,
>> -};
>> -
>>   static int mtk_dsi_probe(struct platform_device *pdev)
>>   {
>>          struct mtk_dsi *dsi;
>>          struct device *dev = &pdev->dev;
>> -       struct drm_panel *panel;
>>          struct resource *regs;
>>          int irq_num;
>>          int ret;
>> @@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>                  return ret;
>>          }
>>
>> -       ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
>> -                                         &panel, &dsi->next_bridge);
>> -       if (ret)
>> -               goto err_unregister_host;
>> -
>> -       if (panel) {
>> -               dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
>> -               if (IS_ERR(dsi->next_bridge)) {
>> -                       ret = PTR_ERR(dsi->next_bridge);
>> -                       goto err_unregister_host;
>> -               }
>> -       }
>> -
>>          dsi->driver_data = of_device_get_match_data(dev);
>>
>>          dsi->engine_clk = devm_clk_get(dev, "engine");
>> @@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>          dsi->bridge.of_node = dev->of_node;
>>          dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
>>
>> -       drm_bridge_add(&dsi->bridge);
>> -
>> -       ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
>> -       if (ret) {
>> -               dev_err(&pdev->dev, "failed to add component: %d\n", ret);
>> -               goto err_unregister_host;
>> -       }
>> -
>>          return 0;
>>
>>   err_unregister_host:
>> @@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
>>          struct mtk_dsi *dsi = platform_get_drvdata(pdev);
>>
>>          mtk_output_dsi_disable(dsi);
>> -       drm_bridge_remove(&dsi->bridge);
>> -       component_del(&pdev->dev, &mtk_dsi_component_ops);
>>          mipi_dsi_host_unregister(&dsi->host);
>>
>>          return 0;
>> --
>> 2.33.1
>>


-- 
AngeloGioacchino Del Regno
Software Engineer

Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
Registered in England & Wales, no. 5513718

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
> Hi, Angelo:
> 
> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
> 2022年1月27日 週四 下午10:36寫道：
>>
>> DRM bridge drivers are now attaching their DSI device at probe time,
>> which requires us to register our DSI host in order to let the bridge
>> to probe: this recently started producing an endless -EPROBE_DEFER
>> loop on some machines that are using external bridges, like the
>> parade-ps8640, found on the ACER Chromebook R13.
>>
>> Now that the DSI hosts/devices probe sequence is documented, we can
>> do adjustments to the mtk_dsi driver as to both fix now and make sure
>> to avoid this situation in the future: for this, following what is
>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
>> mtk_dsi_ops.attach callback and delete it in the detach callback;
>> keeping in mind that we are registering a drm_bridge for our DSI,
>> which is only used/attached if the DSI Host is bound, it wouldn't
>> make sense to keep adding our bridge at probe time (as it would
>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
>> that one to the dsi host attach function (and remove it in detach).
>>
>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
> 
> The fixed tag should indicate the patch which cause the bug, but why a
> patch just adding document would cause bug?
> So no any patch cause bug? This patch just want to prevent a possible bug?
> 

I think you've missed my previous message on v2, so I will paste it here:

unfortunately I couldn't find a valid commit for a Fixes tag. This
started being an issue at some point, when the DRM was changed to
adhere to the documented probe sequence: the MediaTek DSI driver was
not the only one that got broken/affected by these changes.

If you have any advice on which commit should be tagged, I'm open for
any kind of suggestion.


I tried to check on other drivers which got fixed for the same behavior,
for example drm/msm, but none of them had a Fixes tag.
When the DRM got changed to adhere to this sequence, some drm/bridge
drivers were also changed; this has created some incompatibilities with
some drm drivers, including drm/msm and drm/mediatek.

This commit is not fixing a latent bug that was introduced in drm/mediatek
but rather one that was induced by the new, fixed, probe flow that got
recently documented - and to which drivers should adhere; failing to adhere
to that will produce an endless -EPROBE_DEFER loop, due to other drivers
(as mentioned, for example drm/bridge drivers) having been changed to use
that probe sequence.


Regards,
Angelo

> Regards,
> Chun-Kuang.
> 
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>>
>> ---
>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>>   1 file changed, 84 insertions(+), 83 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> index 5d90d2eb0019..bced4c7d668e 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> @@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
>>          mtk_dsi_poweroff(dsi);
>>   }
>>
>> +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
>> +{
>> +       int ret;
>> +
>> +       ret = drm_simple_encoder_init(drm, &dsi->encoder,
>> +                                     DRM_MODE_ENCODER_DSI);
>> +       if (ret) {
>> +               DRM_ERROR("Failed to encoder init to drm\n");
>> +               return ret;
>> +       }
>> +
>> +       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
>> +
>> +       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
>> +                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>> +       if (ret)
>> +               goto err_cleanup_encoder;
>> +
>> +       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
>> +       if (IS_ERR(dsi->connector)) {
>> +               DRM_ERROR("Unable to create bridge connector\n");
>> +               ret = PTR_ERR(dsi->connector);
>> +               goto err_cleanup_encoder;
>> +       }
>> +       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
>> +
>> +       return 0;
>> +
>> +err_cleanup_encoder:
>> +       drm_encoder_cleanup(&dsi->encoder);
>> +       return ret;
>> +}
>> +
>> +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
>> +{
>> +       int ret;
>> +       struct drm_device *drm = data;
>> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> +
>> +       ret = mtk_dsi_encoder_init(drm, dsi);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return device_reset_optional(dev);
>> +}
>> +
>> +static void mtk_dsi_unbind(struct device *dev, struct device *master,
>> +                          void *data)
>> +{
>> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> +
>> +       drm_encoder_cleanup(&dsi->encoder);
>> +}
>> +
>> +static const struct component_ops mtk_dsi_component_ops = {
>> +       .bind = mtk_dsi_bind,
>> +       .unbind = mtk_dsi_unbind,
>> +};
>> +
>>   static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
>>                                 struct mipi_dsi_device *device)
>>   {
>>          struct mtk_dsi *dsi = host_to_dsi(host);
>> +       struct device *dev = host->dev;
>> +       int ret;
>>
>>          dsi->lanes = device->lanes;
>>          dsi->format = device->format;
>>          dsi->mode_flags = device->mode_flags;
>> +       dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
>> +       if (IS_ERR(dsi->next_bridge))
>> +               return PTR_ERR(dsi->next_bridge);
>> +
>> +       drm_bridge_add(&dsi->bridge);
>> +
>> +       ret = component_add(host->dev, &mtk_dsi_component_ops);
>> +       if (ret) {
>> +               DRM_ERROR("failed to add dsi_host component: %d\n", ret);
>> +               drm_bridge_remove(&dsi->bridge);
>> +               return ret;
>> +       }
>>
>>          return 0;
>>   }
>>
>> +static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
>> +                              struct mipi_dsi_device *device)
>> +{
>> +       struct mtk_dsi *dsi = host_to_dsi(host);
>> +
>> +       component_del(host->dev, &mtk_dsi_component_ops);
>> +       drm_bridge_remove(&dsi->bridge);
>> +       return 0;
>> +}
>> +
>>   static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
>>   {
>>          int ret;
>> @@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>>
>>   static const struct mipi_dsi_host_ops mtk_dsi_ops = {
>>          .attach = mtk_dsi_host_attach,
>> +       .detach = mtk_dsi_host_detach,
>>          .transfer = mtk_dsi_host_transfer,
>>   };
>>
>> -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
>> -{
>> -       int ret;
>> -
>> -       ret = drm_simple_encoder_init(drm, &dsi->encoder,
>> -                                     DRM_MODE_ENCODER_DSI);
>> -       if (ret) {
>> -               DRM_ERROR("Failed to encoder init to drm\n");
>> -               return ret;
>> -       }
>> -
>> -       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
>> -
>> -       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
>> -                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>> -       if (ret)
>> -               goto err_cleanup_encoder;
>> -
>> -       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
>> -       if (IS_ERR(dsi->connector)) {
>> -               DRM_ERROR("Unable to create bridge connector\n");
>> -               ret = PTR_ERR(dsi->connector);
>> -               goto err_cleanup_encoder;
>> -       }
>> -       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
>> -
>> -       return 0;
>> -
>> -err_cleanup_encoder:
>> -       drm_encoder_cleanup(&dsi->encoder);
>> -       return ret;
>> -}
>> -
>> -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
>> -{
>> -       int ret;
>> -       struct drm_device *drm = data;
>> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> -
>> -       ret = mtk_dsi_encoder_init(drm, dsi);
>> -       if (ret)
>> -               return ret;
>> -
>> -       return device_reset_optional(dev);
>> -}
>> -
>> -static void mtk_dsi_unbind(struct device *dev, struct device *master,
>> -                          void *data)
>> -{
>> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> -
>> -       drm_encoder_cleanup(&dsi->encoder);
>> -}
>> -
>> -static const struct component_ops mtk_dsi_component_ops = {
>> -       .bind = mtk_dsi_bind,
>> -       .unbind = mtk_dsi_unbind,
>> -};
>> -
>>   static int mtk_dsi_probe(struct platform_device *pdev)
>>   {
>>          struct mtk_dsi *dsi;
>>          struct device *dev = &pdev->dev;
>> -       struct drm_panel *panel;
>>          struct resource *regs;
>>          int irq_num;
>>          int ret;
>> @@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>                  return ret;
>>          }
>>
>> -       ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
>> -                                         &panel, &dsi->next_bridge);
>> -       if (ret)
>> -               goto err_unregister_host;
>> -
>> -       if (panel) {
>> -               dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
>> -               if (IS_ERR(dsi->next_bridge)) {
>> -                       ret = PTR_ERR(dsi->next_bridge);
>> -                       goto err_unregister_host;
>> -               }
>> -       }
>> -
>>          dsi->driver_data = of_device_get_match_data(dev);
>>
>>          dsi->engine_clk = devm_clk_get(dev, "engine");
>> @@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>          dsi->bridge.of_node = dev->of_node;
>>          dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
>>
>> -       drm_bridge_add(&dsi->bridge);
>> -
>> -       ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
>> -       if (ret) {
>> -               dev_err(&pdev->dev, "failed to add component: %d\n", ret);
>> -               goto err_unregister_host;
>> -       }
>> -
>>          return 0;
>>
>>   err_unregister_host:
>> @@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
>>          struct mtk_dsi *dsi = platform_get_drvdata(pdev);
>>
>>          mtk_output_dsi_disable(dsi);
>> -       drm_bridge_remove(&dsi->bridge);
>> -       component_del(&pdev->dev, &mtk_dsi_component_ops);
>>          mipi_dsi_host_unregister(&dsi->host);
>>
>>          return 0;
>> --
>> 2.33.1
>>


-- 
AngeloGioacchino Del Regno
Software Engineer

Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
Registered in England & Wales, no. 5513718

_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
> Hi, Angelo:
> 
> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
> 2022年1月27日 週四 下午10:36寫道：
>>
>> DRM bridge drivers are now attaching their DSI device at probe time,
>> which requires us to register our DSI host in order to let the bridge
>> to probe: this recently started producing an endless -EPROBE_DEFER
>> loop on some machines that are using external bridges, like the
>> parade-ps8640, found on the ACER Chromebook R13.
>>
>> Now that the DSI hosts/devices probe sequence is documented, we can
>> do adjustments to the mtk_dsi driver as to both fix now and make sure
>> to avoid this situation in the future: for this, following what is
>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
>> mtk_dsi_ops.attach callback and delete it in the detach callback;
>> keeping in mind that we are registering a drm_bridge for our DSI,
>> which is only used/attached if the DSI Host is bound, it wouldn't
>> make sense to keep adding our bridge at probe time (as it would
>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
>> that one to the dsi host attach function (and remove it in detach).
>>
>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
> 
> The fixed tag should indicate the patch which cause the bug, but why a
> patch just adding document would cause bug?
> So no any patch cause bug? This patch just want to prevent a possible bug?
> 

I think you've missed my previous message on v2, so I will paste it here:

unfortunately I couldn't find a valid commit for a Fixes tag. This
started being an issue at some point, when the DRM was changed to
adhere to the documented probe sequence: the MediaTek DSI driver was
not the only one that got broken/affected by these changes.

If you have any advice on which commit should be tagged, I'm open for
any kind of suggestion.


I tried to check on other drivers which got fixed for the same behavior,
for example drm/msm, but none of them had a Fixes tag.
When the DRM got changed to adhere to this sequence, some drm/bridge
drivers were also changed; this has created some incompatibilities with
some drm drivers, including drm/msm and drm/mediatek.

This commit is not fixing a latent bug that was introduced in drm/mediatek
but rather one that was induced by the new, fixed, probe flow that got
recently documented - and to which drivers should adhere; failing to adhere
to that will produce an endless -EPROBE_DEFER loop, due to other drivers
(as mentioned, for example drm/bridge drivers) having been changed to use
that probe sequence.


Regards,
Angelo

> Regards,
> Chun-Kuang.
> 
>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>>
>> ---
>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>>   1 file changed, 84 insertions(+), 83 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/mediatek/mtk_dsi.c b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> index 5d90d2eb0019..bced4c7d668e 100644
>> --- a/drivers/gpu/drm/mediatek/mtk_dsi.c
>> +++ b/drivers/gpu/drm/mediatek/mtk_dsi.c
>> @@ -786,18 +786,101 @@ void mtk_dsi_ddp_stop(struct device *dev)
>>          mtk_dsi_poweroff(dsi);
>>   }
>>
>> +static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
>> +{
>> +       int ret;
>> +
>> +       ret = drm_simple_encoder_init(drm, &dsi->encoder,
>> +                                     DRM_MODE_ENCODER_DSI);
>> +       if (ret) {
>> +               DRM_ERROR("Failed to encoder init to drm\n");
>> +               return ret;
>> +       }
>> +
>> +       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
>> +
>> +       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
>> +                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>> +       if (ret)
>> +               goto err_cleanup_encoder;
>> +
>> +       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
>> +       if (IS_ERR(dsi->connector)) {
>> +               DRM_ERROR("Unable to create bridge connector\n");
>> +               ret = PTR_ERR(dsi->connector);
>> +               goto err_cleanup_encoder;
>> +       }
>> +       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
>> +
>> +       return 0;
>> +
>> +err_cleanup_encoder:
>> +       drm_encoder_cleanup(&dsi->encoder);
>> +       return ret;
>> +}
>> +
>> +static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
>> +{
>> +       int ret;
>> +       struct drm_device *drm = data;
>> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> +
>> +       ret = mtk_dsi_encoder_init(drm, dsi);
>> +       if (ret)
>> +               return ret;
>> +
>> +       return device_reset_optional(dev);
>> +}
>> +
>> +static void mtk_dsi_unbind(struct device *dev, struct device *master,
>> +                          void *data)
>> +{
>> +       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> +
>> +       drm_encoder_cleanup(&dsi->encoder);
>> +}
>> +
>> +static const struct component_ops mtk_dsi_component_ops = {
>> +       .bind = mtk_dsi_bind,
>> +       .unbind = mtk_dsi_unbind,
>> +};
>> +
>>   static int mtk_dsi_host_attach(struct mipi_dsi_host *host,
>>                                 struct mipi_dsi_device *device)
>>   {
>>          struct mtk_dsi *dsi = host_to_dsi(host);
>> +       struct device *dev = host->dev;
>> +       int ret;
>>
>>          dsi->lanes = device->lanes;
>>          dsi->format = device->format;
>>          dsi->mode_flags = device->mode_flags;
>> +       dsi->next_bridge = devm_drm_of_get_bridge(dev, dev->of_node, 0, 0);
>> +       if (IS_ERR(dsi->next_bridge))
>> +               return PTR_ERR(dsi->next_bridge);
>> +
>> +       drm_bridge_add(&dsi->bridge);
>> +
>> +       ret = component_add(host->dev, &mtk_dsi_component_ops);
>> +       if (ret) {
>> +               DRM_ERROR("failed to add dsi_host component: %d\n", ret);
>> +               drm_bridge_remove(&dsi->bridge);
>> +               return ret;
>> +       }
>>
>>          return 0;
>>   }
>>
>> +static int mtk_dsi_host_detach(struct mipi_dsi_host *host,
>> +                              struct mipi_dsi_device *device)
>> +{
>> +       struct mtk_dsi *dsi = host_to_dsi(host);
>> +
>> +       component_del(host->dev, &mtk_dsi_component_ops);
>> +       drm_bridge_remove(&dsi->bridge);
>> +       return 0;
>> +}
>> +
>>   static void mtk_dsi_wait_for_idle(struct mtk_dsi *dsi)
>>   {
>>          int ret;
>> @@ -938,73 +1021,14 @@ static ssize_t mtk_dsi_host_transfer(struct mipi_dsi_host *host,
>>
>>   static const struct mipi_dsi_host_ops mtk_dsi_ops = {
>>          .attach = mtk_dsi_host_attach,
>> +       .detach = mtk_dsi_host_detach,
>>          .transfer = mtk_dsi_host_transfer,
>>   };
>>
>> -static int mtk_dsi_encoder_init(struct drm_device *drm, struct mtk_dsi *dsi)
>> -{
>> -       int ret;
>> -
>> -       ret = drm_simple_encoder_init(drm, &dsi->encoder,
>> -                                     DRM_MODE_ENCODER_DSI);
>> -       if (ret) {
>> -               DRM_ERROR("Failed to encoder init to drm\n");
>> -               return ret;
>> -       }
>> -
>> -       dsi->encoder.possible_crtcs = mtk_drm_find_possible_crtc_by_comp(drm, dsi->host.dev);
>> -
>> -       ret = drm_bridge_attach(&dsi->encoder, &dsi->bridge, NULL,
>> -                               DRM_BRIDGE_ATTACH_NO_CONNECTOR);
>> -       if (ret)
>> -               goto err_cleanup_encoder;
>> -
>> -       dsi->connector = drm_bridge_connector_init(drm, &dsi->encoder);
>> -       if (IS_ERR(dsi->connector)) {
>> -               DRM_ERROR("Unable to create bridge connector\n");
>> -               ret = PTR_ERR(dsi->connector);
>> -               goto err_cleanup_encoder;
>> -       }
>> -       drm_connector_attach_encoder(dsi->connector, &dsi->encoder);
>> -
>> -       return 0;
>> -
>> -err_cleanup_encoder:
>> -       drm_encoder_cleanup(&dsi->encoder);
>> -       return ret;
>> -}
>> -
>> -static int mtk_dsi_bind(struct device *dev, struct device *master, void *data)
>> -{
>> -       int ret;
>> -       struct drm_device *drm = data;
>> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> -
>> -       ret = mtk_dsi_encoder_init(drm, dsi);
>> -       if (ret)
>> -               return ret;
>> -
>> -       return device_reset_optional(dev);
>> -}
>> -
>> -static void mtk_dsi_unbind(struct device *dev, struct device *master,
>> -                          void *data)
>> -{
>> -       struct mtk_dsi *dsi = dev_get_drvdata(dev);
>> -
>> -       drm_encoder_cleanup(&dsi->encoder);
>> -}
>> -
>> -static const struct component_ops mtk_dsi_component_ops = {
>> -       .bind = mtk_dsi_bind,
>> -       .unbind = mtk_dsi_unbind,
>> -};
>> -
>>   static int mtk_dsi_probe(struct platform_device *pdev)
>>   {
>>          struct mtk_dsi *dsi;
>>          struct device *dev = &pdev->dev;
>> -       struct drm_panel *panel;
>>          struct resource *regs;
>>          int irq_num;
>>          int ret;
>> @@ -1021,19 +1045,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>                  return ret;
>>          }
>>
>> -       ret = drm_of_find_panel_or_bridge(dev->of_node, 0, 0,
>> -                                         &panel, &dsi->next_bridge);
>> -       if (ret)
>> -               goto err_unregister_host;
>> -
>> -       if (panel) {
>> -               dsi->next_bridge = devm_drm_panel_bridge_add(dev, panel);
>> -               if (IS_ERR(dsi->next_bridge)) {
>> -                       ret = PTR_ERR(dsi->next_bridge);
>> -                       goto err_unregister_host;
>> -               }
>> -       }
>> -
>>          dsi->driver_data = of_device_get_match_data(dev);
>>
>>          dsi->engine_clk = devm_clk_get(dev, "engine");
>> @@ -1098,14 +1109,6 @@ static int mtk_dsi_probe(struct platform_device *pdev)
>>          dsi->bridge.of_node = dev->of_node;
>>          dsi->bridge.type = DRM_MODE_CONNECTOR_DSI;
>>
>> -       drm_bridge_add(&dsi->bridge);
>> -
>> -       ret = component_add(&pdev->dev, &mtk_dsi_component_ops);
>> -       if (ret) {
>> -               dev_err(&pdev->dev, "failed to add component: %d\n", ret);
>> -               goto err_unregister_host;
>> -       }
>> -
>>          return 0;
>>
>>   err_unregister_host:
>> @@ -1118,8 +1121,6 @@ static int mtk_dsi_remove(struct platform_device *pdev)
>>          struct mtk_dsi *dsi = platform_get_drvdata(pdev);
>>
>>          mtk_output_dsi_disable(dsi);
>> -       drm_bridge_remove(&dsi->bridge);
>> -       component_del(&pdev->dev, &mtk_dsi_component_ops);
>>          mipi_dsi_host_unregister(&dsi->host);
>>
>>          return 0;
>> --
>> 2.33.1
>>


-- 
AngeloGioacchino Del Regno
Software Engineer

Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
Registered in England & Wales, no. 5513718

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto:
> Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
>> Hi, Angelo:
>>
>> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
>> 2022年1月27日 週四 下午10:36寫道：
>>>
>>> DRM bridge drivers are now attaching their DSI device at probe time,
>>> which requires us to register our DSI host in order to let the bridge
>>> to probe: this recently started producing an endless -EPROBE_DEFER
>>> loop on some machines that are using external bridges, like the
>>> parade-ps8640, found on the ACER Chromebook R13.
>>>
>>> Now that the DSI hosts/devices probe sequence is documented, we can
>>> do adjustments to the mtk_dsi driver as to both fix now and make sure
>>> to avoid this situation in the future: for this, following what is
>>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
>>> mtk_dsi_ops.attach callback and delete it in the detach callback;
>>> keeping in mind that we are registering a drm_bridge for our DSI,
>>> which is only used/attached if the DSI Host is bound, it wouldn't
>>> make sense to keep adding our bridge at probe time (as it would
>>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
>>> that one to the dsi host attach function (and remove it in detach).
>>>
>>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
>>
>> The fixed tag should indicate the patch which cause the bug, but why a
>> patch just adding document would cause bug?
>> So no any patch cause bug? This patch just want to prevent a possible bug?
>>
> 
> I think you've missed my previous message on v2, so I will paste it here:
> 
> unfortunately I couldn't find a valid commit for a Fixes tag. This
> started being an issue at some point, when the DRM was changed to
> adhere to the documented probe sequence: the MediaTek DSI driver was
> not the only one that got broken/affected by these changes.
> 
> If you have any advice on which commit should be tagged, I'm open for
> any kind of suggestion.
> 
> 
> I tried to check on other drivers which got fixed for the same behavior,
> for example drm/msm, but none of them had a Fixes tag.
> When the DRM got changed to adhere to this sequence, some drm/bridge
> drivers were also changed; this has created some incompatibilities with
> some drm drivers, including drm/msm and drm/mediatek.
> 
> This commit is not fixing a latent bug that was introduced in drm/mediatek
> but rather one that was induced by the new, fixed, probe flow that got
> recently documented - and to which drivers should adhere; failing to adhere
> to that will produce an endless -EPROBE_DEFER loop, due to other drivers
> (as mentioned, for example drm/bridge drivers) having been changed to use
> that probe sequence.
> 
> 
> Regards,
> Angelo
> 

I've been thinking about another solution to this issue.

Would it be fine if I send a v4 that removes the Fixes tag, but adds the following?

Cc: stable@kernel.org # v5.15+

>> Regards,
>> Chun-Kuang.
>>
>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
>>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>>>
>>> ---
>>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>>>   1 file changed, 84 insertions(+), 83 deletions(-)
>>>


-- 
AngeloGioacchino Del Regno
Software Engineer

Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
Registered in England & Wales, no. 5513718

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto:
> Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
>> Hi, Angelo:
>>
>> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
>> 2022年1月27日 週四 下午10:36寫道：
>>>
>>> DRM bridge drivers are now attaching their DSI device at probe time,
>>> which requires us to register our DSI host in order to let the bridge
>>> to probe: this recently started producing an endless -EPROBE_DEFER
>>> loop on some machines that are using external bridges, like the
>>> parade-ps8640, found on the ACER Chromebook R13.
>>>
>>> Now that the DSI hosts/devices probe sequence is documented, we can
>>> do adjustments to the mtk_dsi driver as to both fix now and make sure
>>> to avoid this situation in the future: for this, following what is
>>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
>>> mtk_dsi_ops.attach callback and delete it in the detach callback;
>>> keeping in mind that we are registering a drm_bridge for our DSI,
>>> which is only used/attached if the DSI Host is bound, it wouldn't
>>> make sense to keep adding our bridge at probe time (as it would
>>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
>>> that one to the dsi host attach function (and remove it in detach).
>>>
>>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
>>
>> The fixed tag should indicate the patch which cause the bug, but why a
>> patch just adding document would cause bug?
>> So no any patch cause bug? This patch just want to prevent a possible bug?
>>
> 
> I think you've missed my previous message on v2, so I will paste it here:
> 
> unfortunately I couldn't find a valid commit for a Fixes tag. This
> started being an issue at some point, when the DRM was changed to
> adhere to the documented probe sequence: the MediaTek DSI driver was
> not the only one that got broken/affected by these changes.
> 
> If you have any advice on which commit should be tagged, I'm open for
> any kind of suggestion.
> 
> 
> I tried to check on other drivers which got fixed for the same behavior,
> for example drm/msm, but none of them had a Fixes tag.
> When the DRM got changed to adhere to this sequence, some drm/bridge
> drivers were also changed; this has created some incompatibilities with
> some drm drivers, including drm/msm and drm/mediatek.
> 
> This commit is not fixing a latent bug that was introduced in drm/mediatek
> but rather one that was induced by the new, fixed, probe flow that got
> recently documented - and to which drivers should adhere; failing to adhere
> to that will produce an endless -EPROBE_DEFER loop, due to other drivers
> (as mentioned, for example drm/bridge drivers) having been changed to use
> that probe sequence.
> 
> 
> Regards,
> Angelo
> 

I've been thinking about another solution to this issue.

Would it be fine if I send a v4 that removes the Fixes tag, but adds the following?

Cc: stable@kernel.org # v5.15+

>> Regards,
>> Chun-Kuang.
>>
>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
>>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>>>
>>> ---
>>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>>>   1 file changed, 84 insertions(+), 83 deletions(-)
>>>


-- 
AngeloGioacchino Del Regno
Software Engineer

Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
Registered in England & Wales, no. 5513718

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto:
> Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
>> Hi, Angelo:
>>
>> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
>> 2022年1月27日 週四 下午10:36寫道：
>>>
>>> DRM bridge drivers are now attaching their DSI device at probe time,
>>> which requires us to register our DSI host in order to let the bridge
>>> to probe: this recently started producing an endless -EPROBE_DEFER
>>> loop on some machines that are using external bridges, like the
>>> parade-ps8640, found on the ACER Chromebook R13.
>>>
>>> Now that the DSI hosts/devices probe sequence is documented, we can
>>> do adjustments to the mtk_dsi driver as to both fix now and make sure
>>> to avoid this situation in the future: for this, following what is
>>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
>>> mtk_dsi_ops.attach callback and delete it in the detach callback;
>>> keeping in mind that we are registering a drm_bridge for our DSI,
>>> which is only used/attached if the DSI Host is bound, it wouldn't
>>> make sense to keep adding our bridge at probe time (as it would
>>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
>>> that one to the dsi host attach function (and remove it in detach).
>>>
>>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
>>
>> The fixed tag should indicate the patch which cause the bug, but why a
>> patch just adding document would cause bug?
>> So no any patch cause bug? This patch just want to prevent a possible bug?
>>
> 
> I think you've missed my previous message on v2, so I will paste it here:
> 
> unfortunately I couldn't find a valid commit for a Fixes tag. This
> started being an issue at some point, when the DRM was changed to
> adhere to the documented probe sequence: the MediaTek DSI driver was
> not the only one that got broken/affected by these changes.
> 
> If you have any advice on which commit should be tagged, I'm open for
> any kind of suggestion.
> 
> 
> I tried to check on other drivers which got fixed for the same behavior,
> for example drm/msm, but none of them had a Fixes tag.
> When the DRM got changed to adhere to this sequence, some drm/bridge
> drivers were also changed; this has created some incompatibilities with
> some drm drivers, including drm/msm and drm/mediatek.
> 
> This commit is not fixing a latent bug that was introduced in drm/mediatek
> but rather one that was induced by the new, fixed, probe flow that got
> recently documented - and to which drivers should adhere; failing to adhere
> to that will produce an endless -EPROBE_DEFER loop, due to other drivers
> (as mentioned, for example drm/bridge drivers) having been changed to use
> that probe sequence.
> 
> 
> Regards,
> Angelo
> 

I've been thinking about another solution to this issue.

Would it be fine if I send a v4 that removes the Fixes tag, but adds the following?

Cc: stable@kernel.org # v5.15+

>> Regards,
>> Chun-Kuang.
>>
>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
>>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>>>
>>> ---
>>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>>>   1 file changed, 84 insertions(+), 83 deletions(-)
>>>


-- 
AngeloGioacchino Del Regno
Software Engineer

Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
Registered in England & Wales, no. 5513718

_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[AngeloGioacchino Del Regno]

Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto:
> Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
>> Hi, Angelo:
>>
>> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
>> 2022年1月27日 週四 下午10:36寫道：
>>>
>>> DRM bridge drivers are now attaching their DSI device at probe time,
>>> which requires us to register our DSI host in order to let the bridge
>>> to probe: this recently started producing an endless -EPROBE_DEFER
>>> loop on some machines that are using external bridges, like the
>>> parade-ps8640, found on the ACER Chromebook R13.
>>>
>>> Now that the DSI hosts/devices probe sequence is documented, we can
>>> do adjustments to the mtk_dsi driver as to both fix now and make sure
>>> to avoid this situation in the future: for this, following what is
>>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
>>> mtk_dsi_ops.attach callback and delete it in the detach callback;
>>> keeping in mind that we are registering a drm_bridge for our DSI,
>>> which is only used/attached if the DSI Host is bound, it wouldn't
>>> make sense to keep adding our bridge at probe time (as it would
>>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
>>> that one to the dsi host attach function (and remove it in detach).
>>>
>>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
>>
>> The fixed tag should indicate the patch which cause the bug, but why a
>> patch just adding document would cause bug?
>> So no any patch cause bug? This patch just want to prevent a possible bug?
>>
> 
> I think you've missed my previous message on v2, so I will paste it here:
> 
> unfortunately I couldn't find a valid commit for a Fixes tag. This
> started being an issue at some point, when the DRM was changed to
> adhere to the documented probe sequence: the MediaTek DSI driver was
> not the only one that got broken/affected by these changes.
> 
> If you have any advice on which commit should be tagged, I'm open for
> any kind of suggestion.
> 
> 
> I tried to check on other drivers which got fixed for the same behavior,
> for example drm/msm, but none of them had a Fixes tag.
> When the DRM got changed to adhere to this sequence, some drm/bridge
> drivers were also changed; this has created some incompatibilities with
> some drm drivers, including drm/msm and drm/mediatek.
> 
> This commit is not fixing a latent bug that was introduced in drm/mediatek
> but rather one that was induced by the new, fixed, probe flow that got
> recently documented - and to which drivers should adhere; failing to adhere
> to that will produce an endless -EPROBE_DEFER loop, due to other drivers
> (as mentioned, for example drm/bridge drivers) having been changed to use
> that probe sequence.
> 
> 
> Regards,
> Angelo
> 

I've been thinking about another solution to this issue.

Would it be fine if I send a v4 that removes the Fixes tag, but adds the following?

Cc: stable@kernel.org # v5.15+

>> Regards,
>> Chun-Kuang.
>>
>>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
>>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
>>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
>>>
>>> ---
>>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
>>>   1 file changed, 84 insertions(+), 83 deletions(-)
>>>


-- 
AngeloGioacchino Del Regno
Software Engineer

Collabora Ltd.
Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
Registered in England & Wales, no. 5513718

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[Chun-Kuang Hu]

AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
2022年1月28日 週五 下午5:13寫道：
>
> Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto:
> > Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
> >> Hi, Angelo:
> >>
> >> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
> >> 2022年1月27日 週四 下午10:36寫道：
> >>>
> >>> DRM bridge drivers are now attaching their DSI device at probe time,
> >>> which requires us to register our DSI host in order to let the bridge
> >>> to probe: this recently started producing an endless -EPROBE_DEFER
> >>> loop on some machines that are using external bridges, like the
> >>> parade-ps8640, found on the ACER Chromebook R13.
> >>>
> >>> Now that the DSI hosts/devices probe sequence is documented, we can
> >>> do adjustments to the mtk_dsi driver as to both fix now and make sure
> >>> to avoid this situation in the future: for this, following what is
> >>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
> >>> mtk_dsi_ops.attach callback and delete it in the detach callback;
> >>> keeping in mind that we are registering a drm_bridge for our DSI,
> >>> which is only used/attached if the DSI Host is bound, it wouldn't
> >>> make sense to keep adding our bridge at probe time (as it would
> >>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
> >>> that one to the dsi host attach function (and remove it in detach).
> >>>
> >>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
> >>
> >> The fixed tag should indicate the patch which cause the bug, but why a
> >> patch just adding document would cause bug?
> >> So no any patch cause bug? This patch just want to prevent a possible bug?
> >>
> >
> > I think you've missed my previous message on v2, so I will paste it here:
> >
> > unfortunately I couldn't find a valid commit for a Fixes tag. This
> > started being an issue at some point, when the DRM was changed to
> > adhere to the documented probe sequence: the MediaTek DSI driver was
> > not the only one that got broken/affected by these changes.
> >
> > If you have any advice on which commit should be tagged, I'm open for
> > any kind of suggestion.
> >
> >
> > I tried to check on other drivers which got fixed for the same behavior,
> > for example drm/msm, but none of them had a Fixes tag.
> > When the DRM got changed to adhere to this sequence, some drm/bridge
> > drivers were also changed; this has created some incompatibilities with
> > some drm drivers, including drm/msm and drm/mediatek.
> >
> > This commit is not fixing a latent bug that was introduced in drm/mediatek
> > but rather one that was induced by the new, fixed, probe flow that got
> > recently documented - and to which drivers should adhere; failing to adhere
> > to that will produce an endless -EPROBE_DEFER loop, due to other drivers
> > (as mentioned, for example drm/bridge drivers) having been changed to use
> > that probe sequence.
> >
> >
> > Regards,
> > Angelo
> >
>
> I've been thinking about another solution to this issue.
>
> Would it be fine if I send a v4 that removes the Fixes tag, but adds the following?
>
> Cc: stable@kernel.org # v5.15+

It's ok to me. According to the documented format [1], I think this should be

Cc: <stable@vger.kernel.org> # 5.15.x

[1] https://www.kernel.org/doc/html/v5.16/process/stable-kernel-rules.html

Regards,
Chun-Kuang.

>
> >> Regards,
> >> Chun-Kuang.
> >>
> >>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> >>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
> >>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
> >>>
> >>> ---
> >>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
> >>>   1 file changed, 84 insertions(+), 83 deletions(-)
> >>>
>
>
> --
> AngeloGioacchino Del Regno
> Software Engineer
>
> Collabora Ltd.
> Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
> Registered in England & Wales, no. 5513718

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[Chun-Kuang Hu]

AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
2022年1月28日 週五 下午5:13寫道：
>
> Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto:
> > Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
> >> Hi, Angelo:
> >>
> >> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
> >> 2022年1月27日 週四 下午10:36寫道：
> >>>
> >>> DRM bridge drivers are now attaching their DSI device at probe time,
> >>> which requires us to register our DSI host in order to let the bridge
> >>> to probe: this recently started producing an endless -EPROBE_DEFER
> >>> loop on some machines that are using external bridges, like the
> >>> parade-ps8640, found on the ACER Chromebook R13.
> >>>
> >>> Now that the DSI hosts/devices probe sequence is documented, we can
> >>> do adjustments to the mtk_dsi driver as to both fix now and make sure
> >>> to avoid this situation in the future: for this, following what is
> >>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
> >>> mtk_dsi_ops.attach callback and delete it in the detach callback;
> >>> keeping in mind that we are registering a drm_bridge for our DSI,
> >>> which is only used/attached if the DSI Host is bound, it wouldn't
> >>> make sense to keep adding our bridge at probe time (as it would
> >>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
> >>> that one to the dsi host attach function (and remove it in detach).
> >>>
> >>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
> >>
> >> The fixed tag should indicate the patch which cause the bug, but why a
> >> patch just adding document would cause bug?
> >> So no any patch cause bug? This patch just want to prevent a possible bug?
> >>
> >
> > I think you've missed my previous message on v2, so I will paste it here:
> >
> > unfortunately I couldn't find a valid commit for a Fixes tag. This
> > started being an issue at some point, when the DRM was changed to
> > adhere to the documented probe sequence: the MediaTek DSI driver was
> > not the only one that got broken/affected by these changes.
> >
> > If you have any advice on which commit should be tagged, I'm open for
> > any kind of suggestion.
> >
> >
> > I tried to check on other drivers which got fixed for the same behavior,
> > for example drm/msm, but none of them had a Fixes tag.
> > When the DRM got changed to adhere to this sequence, some drm/bridge
> > drivers were also changed; this has created some incompatibilities with
> > some drm drivers, including drm/msm and drm/mediatek.
> >
> > This commit is not fixing a latent bug that was introduced in drm/mediatek
> > but rather one that was induced by the new, fixed, probe flow that got
> > recently documented - and to which drivers should adhere; failing to adhere
> > to that will produce an endless -EPROBE_DEFER loop, due to other drivers
> > (as mentioned, for example drm/bridge drivers) having been changed to use
> > that probe sequence.
> >
> >
> > Regards,
> > Angelo
> >
>
> I've been thinking about another solution to this issue.
>
> Would it be fine if I send a v4 that removes the Fixes tag, but adds the following?
>
> Cc: stable@kernel.org # v5.15+

It's ok to me. According to the documented format [1], I think this should be

Cc: <stable@vger.kernel.org> # 5.15.x

[1] https://www.kernel.org/doc/html/v5.16/process/stable-kernel-rules.html

Regards,
Chun-Kuang.

>
> >> Regards,
> >> Chun-Kuang.
> >>
> >>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> >>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
> >>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
> >>>
> >>> ---
> >>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
> >>>   1 file changed, 84 insertions(+), 83 deletions(-)
> >>>
>
>
> --
> AngeloGioacchino Del Regno
> Software Engineer
>
> Collabora Ltd.
> Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
> Registered in England & Wales, no. 5513718

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[Chun-Kuang Hu]

AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
2022年1月28日 週五 下午5:13寫道：
>
> Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto:
> > Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
> >> Hi, Angelo:
> >>
> >> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
> >> 2022年1月27日 週四 下午10:36寫道：
> >>>
> >>> DRM bridge drivers are now attaching their DSI device at probe time,
> >>> which requires us to register our DSI host in order to let the bridge
> >>> to probe: this recently started producing an endless -EPROBE_DEFER
> >>> loop on some machines that are using external bridges, like the
> >>> parade-ps8640, found on the ACER Chromebook R13.
> >>>
> >>> Now that the DSI hosts/devices probe sequence is documented, we can
> >>> do adjustments to the mtk_dsi driver as to both fix now and make sure
> >>> to avoid this situation in the future: for this, following what is
> >>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
> >>> mtk_dsi_ops.attach callback and delete it in the detach callback;
> >>> keeping in mind that we are registering a drm_bridge for our DSI,
> >>> which is only used/attached if the DSI Host is bound, it wouldn't
> >>> make sense to keep adding our bridge at probe time (as it would
> >>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
> >>> that one to the dsi host attach function (and remove it in detach).
> >>>
> >>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
> >>
> >> The fixed tag should indicate the patch which cause the bug, but why a
> >> patch just adding document would cause bug?
> >> So no any patch cause bug? This patch just want to prevent a possible bug?
> >>
> >
> > I think you've missed my previous message on v2, so I will paste it here:
> >
> > unfortunately I couldn't find a valid commit for a Fixes tag. This
> > started being an issue at some point, when the DRM was changed to
> > adhere to the documented probe sequence: the MediaTek DSI driver was
> > not the only one that got broken/affected by these changes.
> >
> > If you have any advice on which commit should be tagged, I'm open for
> > any kind of suggestion.
> >
> >
> > I tried to check on other drivers which got fixed for the same behavior,
> > for example drm/msm, but none of them had a Fixes tag.
> > When the DRM got changed to adhere to this sequence, some drm/bridge
> > drivers were also changed; this has created some incompatibilities with
> > some drm drivers, including drm/msm and drm/mediatek.
> >
> > This commit is not fixing a latent bug that was introduced in drm/mediatek
> > but rather one that was induced by the new, fixed, probe flow that got
> > recently documented - and to which drivers should adhere; failing to adhere
> > to that will produce an endless -EPROBE_DEFER loop, due to other drivers
> > (as mentioned, for example drm/bridge drivers) having been changed to use
> > that probe sequence.
> >
> >
> > Regards,
> > Angelo
> >
>
> I've been thinking about another solution to this issue.
>
> Would it be fine if I send a v4 that removes the Fixes tag, but adds the following?
>
> Cc: stable@kernel.org # v5.15+

It's ok to me. According to the documented format [1], I think this should be

Cc: <stable@vger.kernel.org> # 5.15.x

[1] https://www.kernel.org/doc/html/v5.16/process/stable-kernel-rules.html

Regards,
Chun-Kuang.

>
> >> Regards,
> >> Chun-Kuang.
> >>
> >>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> >>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
> >>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
> >>>
> >>> ---
> >>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
> >>>   1 file changed, 84 insertions(+), 83 deletions(-)
> >>>
>
>
> --
> AngeloGioacchino Del Regno
> Software Engineer
>
> Collabora Ltd.
> Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
> Registered in England & Wales, no. 5513718

_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

Re: [PATCH v3] drm/mediatek: mtk_dsi: Avoid EPROBE_DEFER loop with external bridge

[Chun-Kuang Hu]

AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
2022年1月28日 週五 下午5:13寫道：
>
> Il 27/01/22 16:46, AngeloGioacchino Del Regno ha scritto:
> > Il 27/01/22 16:21, Chun-Kuang Hu ha scritto:
> >> Hi, Angelo:
> >>
> >> AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> 於
> >> 2022年1月27日 週四 下午10:36寫道：
> >>>
> >>> DRM bridge drivers are now attaching their DSI device at probe time,
> >>> which requires us to register our DSI host in order to let the bridge
> >>> to probe: this recently started producing an endless -EPROBE_DEFER
> >>> loop on some machines that are using external bridges, like the
> >>> parade-ps8640, found on the ACER Chromebook R13.
> >>>
> >>> Now that the DSI hosts/devices probe sequence is documented, we can
> >>> do adjustments to the mtk_dsi driver as to both fix now and make sure
> >>> to avoid this situation in the future: for this, following what is
> >>> documented in drm_bridge.c, move the mtk_dsi component_add() to the
> >>> mtk_dsi_ops.attach callback and delete it in the detach callback;
> >>> keeping in mind that we are registering a drm_bridge for our DSI,
> >>> which is only used/attached if the DSI Host is bound, it wouldn't
> >>> make sense to keep adding our bridge at probe time (as it would
> >>> be useless to have it if mtk_dsi_ops.attach() fails!), so also move
> >>> that one to the dsi host attach function (and remove it in detach).
> >>>
> >>> Fixes: 209264a85707 ("drm/bridge: Document the probe issue with MIPI-DSI bridges")
> >>
> >> The fixed tag should indicate the patch which cause the bug, but why a
> >> patch just adding document would cause bug?
> >> So no any patch cause bug? This patch just want to prevent a possible bug?
> >>
> >
> > I think you've missed my previous message on v2, so I will paste it here:
> >
> > unfortunately I couldn't find a valid commit for a Fixes tag. This
> > started being an issue at some point, when the DRM was changed to
> > adhere to the documented probe sequence: the MediaTek DSI driver was
> > not the only one that got broken/affected by these changes.
> >
> > If you have any advice on which commit should be tagged, I'm open for
> > any kind of suggestion.
> >
> >
> > I tried to check on other drivers which got fixed for the same behavior,
> > for example drm/msm, but none of them had a Fixes tag.
> > When the DRM got changed to adhere to this sequence, some drm/bridge
> > drivers were also changed; this has created some incompatibilities with
> > some drm drivers, including drm/msm and drm/mediatek.
> >
> > This commit is not fixing a latent bug that was introduced in drm/mediatek
> > but rather one that was induced by the new, fixed, probe flow that got
> > recently documented - and to which drivers should adhere; failing to adhere
> > to that will produce an endless -EPROBE_DEFER loop, due to other drivers
> > (as mentioned, for example drm/bridge drivers) having been changed to use
> > that probe sequence.
> >
> >
> > Regards,
> > Angelo
> >
>
> I've been thinking about another solution to this issue.
>
> Would it be fine if I send a v4 that removes the Fixes tag, but adds the following?
>
> Cc: stable@kernel.org # v5.15+

It's ok to me. According to the documented format [1], I think this should be

Cc: <stable@vger.kernel.org> # 5.15.x

[1] https://www.kernel.org/doc/html/v5.16/process/stable-kernel-rules.html

Regards,
Chun-Kuang.

>
> >> Regards,
> >> Chun-Kuang.
> >>
> >>> Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
> >>> Reviewed-by: Andrzej Hajda <andrzej.hajda@intel.com>
> >>> Reviewed-by: Jagan Teki <jagan@amarulasolutions.com>
> >>>
> >>> ---
> >>>   drivers/gpu/drm/mediatek/mtk_dsi.c | 167 +++++++++++++++--------------
> >>>   1 file changed, 84 insertions(+), 83 deletions(-)
> >>>
>
>
> --
> AngeloGioacchino Del Regno
> Software Engineer
>
> Collabora Ltd.
> Platinum Building, St John's Innovation Park, Cambridge CB4 0DS, UK
> Registered in England & Wales, no. 5513718

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel