[PATCH v2 2/5] drm/i915: Reject async flips if we need to change DDB/watermarks

[Ville Syrjala]

From: Ville Syrjälä <ville.syrj...@linux.intel.com>

DDB/watermarks are always double buffered on the vblank, so we
can't safely change them during async flips. Currently this never
happens, but we'll be making changing between sync and async
flips a bit more flexible, in which case we can actually end up
here.

Reviewed-by: Vandita Kulkarni <vandita.kulka...@intel.com>
Reviewed-by: Arun R Murthy <arun.r.mur...@intel.com>
Signed-off-by: Ville Syrjälä <ville.syrj...@linux.intel.com>
---
 drivers/gpu/drm/i915/display/skl_watermark.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/skl_watermark.c 
b/drivers/gpu/drm/i915/display/skl_watermark.c
index 7c6187b4479f..e6476aa621a7 100644
--- a/drivers/gpu/drm/i915/display/skl_watermark.c
+++ b/drivers/gpu/drm/i915/display/skl_watermark.c
@@ -2540,6 +2540,12 @@ skl_ddb_add_affected_planes(const struct 
intel_crtc_state *old_crtc_state,
                                        
&new_crtc_state->wm.skl.plane_ddb_y[plane_id]))
                        continue;
 
+               if (new_crtc_state->do_async_flip) {
+                       drm_dbg_kms(&i915->drm, "[PLANE:%d:%s] Can't change DDB 
during async flip\n",
+                                   plane->base.base.id, plane->base.name);
+                       return -EINVAL;
+               }
+
                plane_state = intel_atomic_get_plane_state(state, plane);
                if (IS_ERR(plane_state))
                        return PTR_ERR(plane_state);
@@ -2899,6 +2905,12 @@ static int skl_wm_add_affected_planes(struct 
intel_atomic_state *state,
                                                 
&new_crtc_state->wm.skl.optimal))
                        continue;
 
+               if (new_crtc_state->do_async_flip) {
+                       drm_dbg_kms(&i915->drm, "[PLANE:%d:%s] Can't change 
watermarks during async flip\n",
+                                   plane->base.base.id, plane->base.name);
+                       return -EINVAL;
+               }
+
                plane_state = intel_atomic_get_plane_state(state, plane);
                if (IS_ERR(plane_state))
                        return PTR_ERR(plane_state);
-- 
2.43.2