[Intel-gfx] [PATCH] drm/i915: Avoid null dereference if mst_port is unset.

[Chris Wilson]

Quoting Rodrigo Vivi (2017-08-10 15:50:43)
> I'm not sure if this is really the case and I don't believe
> this is the real fix for the bug mentioned here, but since
> I don't see a reliable path when mst_port is set and when
> mode_valid is requested I believe it is worth to have this
> protection here.

The guard looks correct. We defend ourselves against the async
disconnect elsewhere through the post-detect callbacks, i.e. we cannot
rely on intel_connector->mst_port remaining valid for a whole detect()
cycle.

Reviewed-by: Chris Wilson <chris at chris-wilson.co.uk>
-Chris