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drm/bridge: panel: Fix device link for DRM_BRIDGE_ATTACH_NO_CONNECTOR

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When external bridges are attached with DRM_BRIDGE_ATTACH_NO_CONNECTOR,
the panel bridge may also get the same flag, but in the .attach()
callback for the panel bridge a device link is added only when this
flag is not present; To make things worse, the .detach() callback
tries to delete the device link unconditionally and without checking
if it was created in the first place, crashing the kernel with a NULL
pointer kernel panic upon calling panel_bridge_detach().

Fix that by moving the device_link_add() call before checking if the
DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is present.

Fixes: 199cf07ebd ("drm/bridge: panel: Add a device link between drm device and panel device")
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Liu Ying <victor.liu@nxp.com>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20230920082727.57729-1-angelogioacchino.delregno@collabora.com
This commit is contained in:
AngeloGioacchino Del Regno 2023-09-20 10:27:27 +02:00 committed by Neil Armstrong
parent 1c7a387ffe
commit 8878780145
1 changed files with 9 additions and 8 deletions
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17
drivers/gpu/drm/bridge/panel.c
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@ -67,14 +67,6 @@ static int panel_bridge_attach(struct drm_bridge *bridge,
struct drm_device *drm_dev = bridge->dev;
int ret;
if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
return 0;
if (!bridge->encoder) {
DRM_ERROR("Missing encoder\n");
return -ENODEV;
}
panel_bridge->link = device_link_add(drm_dev->dev, panel->dev,
DL_FLAG_STATELESS);
if (!panel_bridge->link) {
@ -83,6 +75,15 @@ static int panel_bridge_attach(struct drm_bridge *bridge,
return -EINVAL;
}
if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
return 0;
if (!bridge->encoder) {
DRM_ERROR("Missing encoder\n");
device_link_del(panel_bridge->link);
return -ENODEV;
}
drm_connector_helper_add(connector,
&panel_bridge_connector_helper_funcs);