Commit 39d5b6a6 authored by Liu Ying's avatar Liu Ying Committed by Linus Walleij
Browse files

drm/bridge: panel: Check device dependency before managing device link 



Some panel devices already depend on DRM device, like the panel in
arch/arm/boot/dts/st/ste-ux500-samsung-skomer.dts, because DRM device is
the ancestor of those panel devices.  device_link_add() would fail by
returning a NULL pointer for those panel devices because of the existing
dependency.  So, check the dependency by calling device_is_dependent()
before adding or deleting device link between panel device and DRM device
so that the link is managed only for independent panel devices.

Fixes: 88787801 ("drm/bridge: panel: Fix device link for DRM_BRIDGE_ATTACH_NO_CONNECTOR")
Fixes: 199cf07e ("drm/bridge: panel: Add a device link between drm device and panel device")
Reported-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Closes: https://lore.kernel.org/lkml/CACRpkdaGzXD6HbiX7mVUNJAJtMEPG00Pp6+nJ1P0JrfJ-ArMvQ@mail.gmail.com/T/


Tested-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarLiu Ying <victor.liu@nxp.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20231123032615.3760488-1-victor.liu@nxp.com
parent ab93edb2

drivers/gpu/drm/bridge/panel.c

+18 −9
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ struct panel_bridge { 
	struct drm_panel *panel;

	struct device_link *link;

	u32 connector_type;

	bool is_independent;

};



static inline struct panel_bridge *
@@ -67,6 +68,10 @@ static int panel_bridge_attach(struct drm_bridge *bridge, 
	struct drm_device *drm_dev = bridge->dev;

	int ret;



	panel_bridge->is_independent = !device_is_dependent(drm_dev->dev,

							    panel->dev);



	if (panel_bridge->is_independent) {

		panel_bridge->link = device_link_add(drm_dev->dev, panel->dev,

						     DL_FLAG_STATELESS);

		if (!panel_bridge->link) {
@@ -74,12 +79,14 @@ static int panel_bridge_attach(struct drm_bridge *bridge, 
				  dev_name(drm_dev->dev), dev_name(panel->dev));

			return -EINVAL;

		}

	}



	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)

		return 0;



	if (!bridge->encoder) {

		DRM_ERROR("Missing encoder\n");

		if (panel_bridge->is_independent)

			device_link_del(panel_bridge->link);

		return -ENODEV;

	}
@@ -92,6 +99,7 @@ static int panel_bridge_attach(struct drm_bridge *bridge, 
				 panel_bridge->connector_type);

	if (ret) {

		DRM_ERROR("Failed to initialize connector\n");

		if (panel_bridge->is_independent)

			device_link_del(panel_bridge->link);

		return ret;

	}
@@ -115,6 +123,7 @@ static void panel_bridge_detach(struct drm_bridge *bridge) 
	struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge);

	struct drm_connector *connector = &panel_bridge->connector;



	if (panel_bridge->is_independent)

		device_link_del(panel_bridge->link);



	/*