[PATCH v3 05/21] drm/bridge: Introduce drm_bridge_chain_get_next_bridge()

[Boris Brezillon <boris.brezillon@collabora.com>]

And use it in drivers accessing the bridge->next field directly.
This is part of our attempt to make the bridge chain a double-linked list
based on the generic list helpers.

Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
---
Changes in v3:
* Inline drm_bridge_chain_get_next_bridge() (Suggested by Laurent)

Changes in v2:
* Kill the last/first helpers (they're not really needed)
* Drop the !bridge || !bridge->encoder test
---
 drivers/gpu/drm/exynos/exynos_drm_dsi.c |  3 ++-
 drivers/gpu/drm/mediatek/mtk_hdmi.c     |  6 ++++--
 drivers/gpu/drm/omapdrm/omap_drv.c      |  4 ++--
 drivers/gpu/drm/omapdrm/omap_encoder.c  |  3 ++-
 drivers/gpu/drm/vc4/vc4_dsi.c           |  4 +++-
 include/drm/drm_bridge.h                | 13 +++++++++++++
 6 files changed, 26 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/exynos/exynos_drm_dsi.c b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
index 3915f50b005e..005c67894b78 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_dsi.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_dsi.c
@@ -1593,9 +1593,10 @@ static int exynos_dsi_host_detach(struct mipi_dsi_host *host,
 				  struct mipi_dsi_device *device)
 {
 	struct exynos_dsi *dsi = host_to_dsi(host);
-	struct drm_bridge *out_bridge = dsi->bridge.next;
 	struct drm_device *drm = dsi->encoder.dev;
+	struct drm_bridge *out_bridge;
 
+	out_bridge = drm_bridge_chain_get_next_bridge(&dsi->bridge);
 	if (dsi->panel) {
 		mutex_lock(&drm->mode_config.mutex);
 		exynos_dsi_disable(&dsi->bridge);
diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
index ea68b5adccbe..cfaa5aab8876 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
@@ -1238,16 +1238,18 @@ static int mtk_hdmi_conn_mode_valid(struct drm_connector *conn,
 				    struct drm_display_mode *mode)
 {
 	struct mtk_hdmi *hdmi = hdmi_ctx_from_conn(conn);
+	struct drm_bridge *next_bridge;
 
 	dev_dbg(hdmi->dev, "xres=%d, yres=%d, refresh=%d, intl=%d clock=%d\n",
 		mode->hdisplay, mode->vdisplay, mode->vrefresh,
 		!!(mode->flags & DRM_MODE_FLAG_INTERLACE), mode->clock * 1000);
 
-	if (hdmi->bridge.next) {
+	next_bridge = drm_bridge_chain_get_next_bridge(&hdmi->bridge);
+	if (next_bridge) {
 		struct drm_display_mode adjusted_mode;
 
 		drm_mode_copy(&adjusted_mode, mode);
-		if (!drm_bridge_chain_mode_fixup(hdmi->bridge.next, mode,
+		if (!drm_bridge_chain_mode_fixup(next_bridge, mode,
 						 &adjusted_mode))
 			return MODE_BAD;
 	}
diff --git a/drivers/gpu/drm/omapdrm/omap_drv.c b/drivers/gpu/drm/omapdrm/omap_drv.c
index b3e22c890c51..865164fe28dc 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -217,8 +217,8 @@ static int omap_display_id(struct omap_dss_device *output)
 	} else if (output->bridge) {
 		struct drm_bridge *bridge = output->bridge;
 
-		while (bridge->next)
-			bridge = bridge->next;
+		while (drm_bridge_chain_get_next_bridge(bridge))
+			bridge = drm_bridge_chain_get_next_bridge(bridge);
 
 		node = bridge->of_node;
 	} else if (output->panel) {
diff --git a/drivers/gpu/drm/omapdrm/omap_encoder.c b/drivers/gpu/drm/omapdrm/omap_encoder.c
index 24bbe9f2a32e..8ca54081997e 100644
--- a/drivers/gpu/drm/omapdrm/omap_encoder.c
+++ b/drivers/gpu/drm/omapdrm/omap_encoder.c
@@ -126,7 +126,8 @@ static void omap_encoder_mode_set(struct drm_encoder *encoder,
 	for (dssdev = output; dssdev; dssdev = dssdev->next)
 		omap_encoder_update_videomode_flags(&vm, dssdev->bus_flags);
 
-	for (bridge = output->bridge; bridge; bridge = bridge->next) {
+	for (bridge = output->bridge; bridge;
+	     bridge = drm_bridge_chain_get_next_bridge(bridge)) {
 		if (!bridge->timings)
 			continue;
 
diff --git a/drivers/gpu/drm/vc4/vc4_dsi.c b/drivers/gpu/drm/vc4/vc4_dsi.c
index 49f8a313e759..49c47185aff0 100644
--- a/drivers/gpu/drm/vc4/vc4_dsi.c
+++ b/drivers/gpu/drm/vc4/vc4_dsi.c
@@ -1644,8 +1644,10 @@ static void vc4_dsi_unbind(struct device *dev, struct device *master,
 	struct drm_device *drm = dev_get_drvdata(master);
 	struct vc4_dev *vc4 = to_vc4_dev(drm);
 	struct vc4_dsi *dsi = dev_get_drvdata(dev);
+	struct drm_bridge *bridge;
 
-	if (dsi->bridge.next)
+	bridge = drm_bridge_chain_get_next_bridge(&dsi->bridge);
+	if (bridge)
 		pm_runtime_disable(dev);
 
 	vc4_dsi_encoder_destroy(dsi->encoder);
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 726435baf4ad..8aeba83fcf31 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -409,6 +409,19 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np);
 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 		      struct drm_bridge *previous);
 
+/**
+ * drm_bridge_chain_get_next_bridge() - Get the next bridge in the chain
+ * @bridge: bridge object
+ *
+ * RETURNS:
+ * the next bridge in the chain, or NULL if @bridge is the last.
+ */
+static inline struct drm_bridge *
+drm_bridge_chain_get_next_bridge(struct drm_bridge *bridge)
+{
+	return bridge->next;
+}
+
 bool drm_bridge_chain_mode_fixup(struct drm_bridge *bridge,
 				 const struct drm_display_mode *mode,
 				 struct drm_display_mode *adjusted_mode);
-- 
2.21.0