[Intel-gfx] [PATCH 1/6] drm/i915/fbc: Reject PLANE_OFFSET.y%4!=0 on icl+ too

[Ville Syrjala]

From: Ville Syrjälä <ville.syrjala at linux.intel.com>

icl and tgl are still affected by the modulo 4 PLANE_OFFSET.y
underrun issue. Reject such configurations on all gen9+ platforms.

Can be reproduced easily with the following sequence of
hardware poking:
while {
  write FBC_CTL.enable=1
  wait for vblank

  write PLANE_OFFSET .x=0 .y=32
  write PLANE_SURF
  wait for vblank

  # if PLANE_OFFSET.y is multiple of 4 the underrun won't happen
  write PLANE_OFFSET .x=0 .y=31
  write PLANE_SURF
  wait for vblank

  # extra vblank wait is required here presumably
  # to get FBC into the proper state
  wait for vblank

  write FBC_CTL.enable=0
  # underrun happens some time after FBC disable
  wait for vblank
}

Both 8888 and 565 pixel formats and all tilinga formats
seem affected. Reproduced on KBL/GLK/ICL/TGL. BDW confirmed
not affected.

Closes: https://gitlab.freedesktop.org/drm/intel/issues/792
Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
---
 drivers/gpu/drm/i915/display/intel_fbc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 6f1d5c032681..a1048ece541e 100644
--- a/drivers/gpu/drm/i915/display/intel_fbc.c
+++ b/drivers/gpu/drm/i915/display/intel_fbc.c
@@ -776,7 +776,7 @@ static bool intel_fbc_can_activate(struct intel_crtc *crtc)
 	 * having a Y offset that isn't divisible by 4 causes FIFO underrun
 	 * and screen flicker.
 	 */
-	if (IS_GEN_RANGE(dev_priv, 9, 10) &&
+	if (INTEL_GEN(dev_priv) >= 9 &&
 	    (fbc->state_cache.plane.adjusted_y & 3)) {
 		fbc->no_fbc_reason = "plane Y offset is misaligned";
 		return false;
-- 
2.23.0