[PATCH] drm/bridge: panel: Check device dependency before managing device link

[Linus Walleij]

On Thu, Nov 23, 2023 at 4:22 AM Liu Ying <victor.liu at nxp.com> wrote:

> 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: 887878014534 ("drm/bridge: panel: Fix device link for DRM_BRIDGE_ATTACH_NO_CONNECTOR")
> Fixes: 199cf07ebd2b ("drm/bridge: panel: Add a device link between drm device and panel device")
> Reported-by: Linus Walleij <linus.walleij at linaro.org>
> Closes: https://lore.kernel.org/lkml/CACRpkdaGzXD6HbiX7mVUNJAJtMEPG00Pp6+nJ1P0JrfJ-ArMvQ@mail.gmail.com/T/
> Tested-by: Linus Walleij <linus.walleij at linaro.org>
> Signed-off-by: Liu Ying <victor.liu at nxp.com>

Patch applied to drm-misc-fixes.

Yours,
Linus Walleij