drm/i915: Skip vcpi allocation for MSTB ports that are gone
authorLyude Paul <lyude@redhat.com>
Mon, 8 Oct 2018 23:24:33 +0000 (19:24 -0400)
committerLyude Paul <lyude@redhat.com>
Tue, 9 Oct 2018 15:12:23 +0000 (11:12 -0400)
commitf67207d78ceaf98b7531bc22df6f21328559c8d4
treecb3b75ebe054fab21e46622d6127f09244da0f39
parent6ed5bb1fbad34382c8cfe9a9bf737e9a43053df5
drm/i915: Skip vcpi allocation for MSTB ports that are gone

Since we need to be able to allow DPMS on->off prop changes after an MST
port has disappeared from the system, we need to be able to make sure we
can compute a config for the resulting atomic commit. Currently this is
impossible when the port has disappeared, since the VCPI slot searching
we try to do in intel_dp_mst_compute_config() will fail with -EINVAL.

Since the only commits we want to allow on no-longer-present MST ports
are ones that shut off display hardware, we already know that no VCPI
allocations are needed. So, hardcode the VCPI slot count to 0 when
intel_dp_mst_compute_config() is called on an MST port that's gone.

Changes since V4:
- Don't use mst_port_gone at all, just check whether or not the drm
  connector is registered - Daniel Vetter

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/20181008232437.5571-5-lyude@redhat.com
drivers/gpu/drm/i915/intel_dp_mst.c