[PATCH 5/6] drm/amdgpu/dm/mst: Report possible_crtcs incorrectly, for now

[Lyude Paul <lyude@redhat.com>]

This commit is seperate from the previous one to make it easier to
revert in the future. Basically, there's multiple userspace applications
that interpret possible_crtcs very wrong:

https://gitlab.freedesktop.org/xorg/xserver/merge_requests/277
https://gitlab.gnome.org/GNOME/mutter/issues/759

While work is ongoing to fix these issues in userspace, we need to
report ->possible_crtcs incorrectly for now in order to avoid
introducing a regression in in userspace. Once these issues get fixed,
this commit should be reverted.

Signed-off-by: Lyude Paul <lyude@redhat.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index b404f1ae6df7..fe8ac801d7a5 100644
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -4807,6 +4807,17 @@ static int amdgpu_dm_crtc_init(struct amdgpu_display_manager *dm,
 	if (!acrtc->mst_encoder)
 		goto fail;
 
+	/*
+	 * FIXME: This is a hack to workaround the following issues:
+	 *
+	 * https://gitlab.gnome.org/GNOME/mutter/issues/759
+	 * https://gitlab.freedesktop.org/xorg/xserver/merge_requests/277
+	 *
+	 * One these issues are closed, this should be removed
+	 */
+	acrtc->mst_encoder->base.possible_crtcs =
+		amdgpu_dm_get_encoder_crtc_mask(dm->adev);
+
 	return 0;
 
 fail:
-- 
2.21.0