[PATCH 2/2 RESEND] drm/bridge: Add extra checks in pre_enable and post_enable

[AngeloGioacchino Del Regno]

Il 11/03/22 10:34, Ricardo Cañuelo ha scritto:
> Depending on the bridge code, certain userspace events during a driver
> teardown (such as a DRM ioctl call) might cause a race condition where
> the drm_bridge_chain_pre_enable() and drm_bridge_chain_post_enable()
> functions could be called for a bridge that has just been detached and
> removed from the bridge chain of an encoder.
> 
> This change makes these functions a bit more robust by bailing out if
> the bridge has already been detached.
> 
> Tested on an Acer Chromebook R13 (Elm, MT8173) with Debian Sid.
> 
> Signed-off-by: Ricardo Cañuelo <ricardo.canuelo at collabora.com>

On various chromebooks with different MediaTek SoC models, and on
Qualcomm SC7180 Trogdor,

Tested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno at collabora.com>