[PATCH 05/17] drm/imx: parallel-display: split encoder and decoder states

From: Marco Felsch <m.felsch@pengutronix.de>
To: p.zabel@pengutronix.de, airlied@linux.ie, daniel@ffwll.ch,
	shawnguo@kernel.org, stefan@agner.ch, rmk+kernel@armlinux.org.uk
Cc: kernel@pengutronix.de, linux-arm-kernel@lists.infradead.org,
	dri-devel@lists.freedesktop.org
Subject: [PATCH 05/17] drm/imx: parallel-display: split encoder and decoder states
Date: Thu, 27 Feb 2020 17:21:13 +0100	[thread overview]
Message-ID: <20200227162125.10450-6-m.felsch@pengutronix.de> (raw)
In-Reply-To: <20200227162125.10450-1-m.felsch@pengutronix.de>

This commit prepares the driver to fix the race condition reported by
[1]. The goal is to switch from the devres-kmalloc and the component
framework to a 'normal' kmalloc and the drm framework to release the
memory resources. So all acquired memory resoruces are freed by a
drm_mode_config_cleanup() call and the ->destroy() callbacks. For this
purpose we need to split off the drm_connector structure.

[1] https://www.spinics.net/lists/dri-devel/msg189388.html

Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
---
 drivers/gpu/drm/imx/parallel-display.c | 84 ++++++++++++++++----------
 1 file changed, 53 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/imx/parallel-display.c b/drivers/gpu/drm/imx/parallel-display.c
index e731b19fd6b2..a05808982f2f 100644
--- a/drivers/gpu/drm/imx/parallel-display.c
+++ b/drivers/gpu/drm/imx/parallel-display.c
@@ -22,21 +22,25 @@
 #include "imx-drm.h"
 
 struct imx_parallel_display {
-	struct drm_connector connector;
 	struct drm_encoder encoder;
 	struct device *dev;
-	void *edid;
-	int edid_len;
 	u32 bus_format;
 	u32 bus_flags;
-	struct drm_display_mode mode;
 	struct drm_panel *panel;
 	struct drm_bridge *bridge;
 };
 
-static inline struct imx_parallel_display *con_to_imxpd(struct drm_connector *c)
+struct imx_parallel_connector {
+	struct imx_parallel_display *imxpd;
+	struct drm_connector connector;
+	void *edid;
+	int edid_len;
+	struct drm_display_mode mode;
+};
+
+static inline struct imx_parallel_connector *con_to_imxpc(struct drm_connector *c)
 {
-	return container_of(c, struct imx_parallel_display, connector);
+	return container_of(c, struct imx_parallel_connector, connector);
 }
 
 static inline struct imx_parallel_display *enc_to_imxpd(struct drm_encoder *e)
@@ -44,9 +48,19 @@ static inline struct imx_parallel_display *enc_to_imxpd(struct drm_encoder *e)
 	return container_of(e, struct imx_parallel_display, encoder);
 }
 
+static void imx_pd_connector_destroy(struct drm_connector *connector)
+{
+	struct imx_parallel_connector *imxpc = con_to_imxpc(connector);
+
+	imx_drm_connector_destroy(connector);
+	/* avoid dangling pointer */
+	imxpc->imxpd = NULL;
+}
+
 static int imx_pd_connector_get_modes(struct drm_connector *connector)
 {
-	struct imx_parallel_display *imxpd = con_to_imxpd(connector);
+	struct imx_parallel_connector *imxpc = con_to_imxpc(connector);
+	struct imx_parallel_display *imxpd = imxpc->imxpd;
 	struct device_node *np = imxpd->dev->of_node;
 	int num_modes;
 
@@ -54,9 +68,9 @@ static int imx_pd_connector_get_modes(struct drm_connector *connector)
 	if (num_modes > 0)
 		return num_modes;
 
-	if (imxpd->edid) {
-		drm_connector_update_edid_property(connector, imxpd->edid);
-		num_modes = drm_add_edid_modes(connector, imxpd->edid);
+	if (imxpc->edid) {
+		drm_connector_update_edid_property(connector, imxpc->edid);
+		num_modes = drm_add_edid_modes(connector, imxpc->edid);
 	}
 
 	if (np) {
@@ -66,13 +80,13 @@ static int imx_pd_connector_get_modes(struct drm_connector *connector)
 		if (!mode)
 			return -EINVAL;
 
-		ret = of_get_drm_display_mode(np, &imxpd->mode,
+		ret = of_get_drm_display_mode(np, &imxpc->mode,
 					      &imxpd->bus_flags,
 					      OF_USE_NATIVE_MODE);
 		if (ret)
 			return ret;
 
-		drm_mode_copy(mode, &imxpd->mode);
+		drm_mode_copy(mode, &imxpc->mode);
 		mode->type |= DRM_MODE_TYPE_DRIVER | DRM_MODE_TYPE_PREFERRED,
 		drm_mode_probed_add(connector, mode);
 		num_modes++;
@@ -129,7 +143,7 @@ static int imx_pd_encoder_atomic_check(struct drm_encoder *encoder,
 
 static const struct drm_connector_funcs imx_pd_connector_funcs = {
 	.fill_modes = drm_helper_probe_single_connector_modes,
-	.destroy = imx_drm_connector_destroy,
+	.destroy = imx_pd_connector_destroy,
 	.reset = drm_atomic_helper_connector_reset,
 	.atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
@@ -150,7 +164,8 @@ static const struct drm_encoder_helper_funcs imx_pd_encoder_helper_funcs = {
 };
 
 static int imx_pd_register(struct drm_device *drm,
-	struct imx_parallel_display *imxpd)
+			   struct imx_parallel_display *imxpd,
+			   struct imx_parallel_connector *imxpc)
 {
 	struct drm_encoder *encoder = &imxpd->encoder;
 	int ret;
@@ -159,27 +174,26 @@ static int imx_pd_register(struct drm_device *drm,
 	if (ret)
 		return ret;
 
-	/* set the connector's dpms to OFF so that
-	 * drm_helper_connector_dpms() won't return
-	 * immediately since the current state is ON
-	 * at this point.
-	 */
-	imxpd->connector.dpms = DRM_MODE_DPMS_OFF;
-
 	drm_encoder_helper_add(encoder, &imx_pd_encoder_helper_funcs);
 	drm_encoder_init(drm, encoder, &imx_pd_encoder_funcs,
 			 DRM_MODE_ENCODER_NONE, NULL);
 
 	if (!imxpd->bridge) {
-		drm_connector_helper_add(&imxpd->connector,
+		/* set the connector's dpms to OFF so that
+		 * drm_helper_connector_dpms() won't return
+		 * immediately since the current state is ON
+		 * at this point.
+		 */
+		imxpc->connector.dpms = DRM_MODE_DPMS_OFF;
+		drm_connector_helper_add(&imxpc->connector,
 				&imx_pd_connector_helper_funcs);
-		drm_connector_init(drm, &imxpd->connector,
+		drm_connector_init(drm, &imxpc->connector,
 				   &imx_pd_connector_funcs,
 				   DRM_MODE_CONNECTOR_DPI);
 	}
 
 	if (imxpd->panel)
-		drm_panel_attach(imxpd->panel, &imxpd->connector);
+		drm_panel_attach(imxpd->panel, &imxpc->connector);
 
 	if (imxpd->bridge) {
 		ret = drm_bridge_attach(encoder, imxpd->bridge, NULL);
@@ -189,7 +203,7 @@ static int imx_pd_register(struct drm_device *drm,
 			return ret;
 		}
 	} else {
-		drm_connector_attach_encoder(&imxpd->connector, encoder);
+		drm_connector_attach_encoder(&imxpc->connector, encoder);
 	}
 
 	return 0;
@@ -201,6 +215,7 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
 	struct device_node *np = dev->of_node;
 	const u8 *edidp;
 	struct imx_parallel_display *imxpd;
+	struct imx_parallel_connector *imxpc;
 	int ret;
 	u32 bus_format = 0;
 	const char *fmt;
@@ -214,10 +229,18 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
 	if (ret && ret != -ENODEV)
 		return ret;
 
-	edidp = of_get_property(np, "edid", &imxpd->edid_len);
-	if (edidp)
-		imxpd->edid = devm_kmemdup(dev, edidp, imxpd->edid_len,
-					   GFP_KERNEL);
+	if (!imxpd->bridge) {
+		imxpc = devm_kzalloc(dev, sizeof(*imxpc), GFP_KERNEL);
+		if (!imxpc)
+			return -ENOMEM;
+
+		imxpc->imxpd = imxpd;
+
+		edidp = of_get_property(np, "edid", &imxpc->edid_len);
+		if (edidp)
+			imxpc->edid = devm_kmemdup(dev, edidp, imxpc->edid_len,
+						   GFP_KERNEL);
+	}
 
 	ret = of_property_read_string(np, "interface-pix-fmt", &fmt);
 	if (!ret) {
@@ -232,10 +255,9 @@ static int imx_pd_bind(struct device *dev, struct device *master, void *data)
 	}
 	imxpd->bus_format = bus_format;
 
-
 	imxpd->dev = dev;
 
-	ret = imx_pd_register(drm, imxpd);
+	ret = imx_pd_register(drm, imxpd, imxpc);
 	if (ret)
 		return ret;
 
-- 
2.20.1


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