drm/bridge: Introduce drm_bridge_get_next_bridge()

[ Upstream commit fadf872d9d9274a3be34d8438e0f6bb465c8f98b ]

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>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191203141515.3597631-3-boris.brezillon@collabora.com
Stable-dep-of: 13fcfcb2a9a4 ("drm/msm/mdp5: Add check for kzalloc")
Signed-off-by: Sasha Levin <sashal@kernel.org>

5 files changed, 22 insertions, 6 deletions

diff --git a/drivers/gpu/drm/drm_encoder.c b/drivers/gpu/drm/drm_encoder.c
index 7fb47b7b8b44..80ce9e1040de 100644
--- a/drivers/gpu/drm/drm_encoder.c
+++ b/drivers/gpu/drm/drm_encoder.c
@@ -170,7 +170,7 @@ void drm_encoder_cleanup(struct drm_encoder *encoder)
 		struct drm_bridge *next;
 
 		while (bridge) {
-			next = bridge->next;
+			next = drm_bridge_get_next_bridge(bridge);
 			drm_bridge_detach(bridge);
 			bridge = next;
 		}
diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi.c b/drivers/gpu/drm/mediatek/mtk_hdmi.c
index 37960172a3a1..74a54a9e3533 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi.c
@@ -1237,16 +1237,18 @@ 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_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 2983c003698e..a4645b78f737 100644
--- a/drivers/gpu/drm/omapdrm/omap_drv.c
+++ b/drivers/gpu/drm/omapdrm/omap_drv.c
@@ -216,8 +216,8 @@ 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_get_next_bridge(bridge))
+			bridge = drm_bridge_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 6fe14111cd95..b626b543a992 100644
--- a/drivers/gpu/drm/omapdrm/omap_encoder.c
+++ b/drivers/gpu/drm/omapdrm/omap_encoder.c
@@ -125,7 +125,8 @@ 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_get_next_bridge(bridge)) {
 		if (!bridge->timings)
 			continue;
 
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 442a0654e1bf..9f7192366cfb 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_get_next_bridge() - Get the next bridge in the chain
+ * @bridge: bridge object
+ *
+ * RETURNS:
+ * the next bridge in the chain after @bridge, or NULL if @bridge is the last.
+ */
+static inline struct drm_bridge *
+drm_bridge_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);