[PATCH v1 8/8] drm/i915/fbc: handle dirty rect coords for the first frame

[Vinod Govindapillai]

During enablig FBC, for the very first frame, the prepare dirty
rect routine wouldnt have executed as at that time the plane
reference in the fbc_state would be NULL. So this could make
driver program some invalid entries as the damage area. Though
fbc hw ignores the dirty rect values programmed for the first
frame after enabling FBC, driver must ensure that valid dirty
rect coords are programmed. So ensure that for the first frame
prepare dirty rect is called at the time enabling FBC.

Signed-off-by: Vinod Govindapillai <vinod.govindapillai at intel.com>
---
 drivers/gpu/drm/i915/display/intel_fbc.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 6222eea4b1ce..21fd57c7f163 100644
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -1230,6 +1230,8 @@ intel_fbc_dirty_rect_update(struct intel_dsb *dsb, struct intel_fbc *fbc)
 
 	lockdep_assert_held(&fbc->lock);
 
+	drm_WARN_ON(display->drm, fbc_dirty_rect->y2 == 0);
+
 	intel_de_write_dsb(display, dsb, XE3_FBC_DIRTY_RECT(fbc->id),
 			   FBC_DIRTY_RECT_START_LINE(fbc_dirty_rect->y1) |
 			   FBC_DIRTY_RECT_END_LINE(fbc_dirty_rect->y2 - 1));
@@ -1313,6 +1315,13 @@ static void intel_fbc_update_state(struct intel_atomic_state *state,
 	WARN_ON(plane_state->no_fbc_reason);
 	WARN_ON(fbc_state->plane && fbc_state->plane != plane);
 
+	/*
+	 * For the very first frame while enabling FBC, ensure that we have a
+	 * valid dirty rect coords.
+	 */
+	if (HAS_FBC_DIRTY_RECT(display) && !fbc_state->plane)
+		__intel_fbc_prepare_dirty_rect(plane_state);
+
 	fbc_state->plane = plane;
 
 	/* FBC1 compression interval: arbitrary choice of 1 second */
-- 
2.43.0