drm/i915: Fix intel_dp_mst_best_encoder()
authorLyude Paul <lyude@redhat.com>
Mon, 8 Oct 2018 23:24:34 +0000 (19:24 -0400)
committerLyude Paul <lyude@redhat.com>
Tue, 9 Oct 2018 15:12:23 +0000 (11:12 -0400)
commita9f9ca33d1fe9325f414914be526c0fc4ba5281c
treeebb7b1a173a98b3d995d7d6101ab4841480e42b3
parentf67207d78ceaf98b7531bc22df6f21328559c8d4
drm/i915: Fix intel_dp_mst_best_encoder()

Currently, i915 appears to rely on blocking modesets on
no-longer-present MSTB ports by simply returning NULL for
->best_encoder(), which in turn causes any new atomic commits that don't
disable the CRTC to fail. This is wrong however, since we still want to
allow userspace to disable CRTCs on no-longer-present MSTB ports by
changing the DPMS state to off and this still requires that we retrieve
an encoder.

So, fix this by always returning a valid encoder regardless of the state
of the MST port.

Changes since v1:
- Remove mst atomic helper, since this got replaced with a much simpler
  solution

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: stable@vger.kernel.org
Link: https://patchwork.freedesktop.org/patch/msgid/20181008232437.5571-6-lyude@redhat.com
drivers/gpu/drm/i915/intel_dp_mst.c