drm/i915/fbc: Reject PLANE_OFFSET.y%4!=0 on icl+ too

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@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191213133453.22152-1-ville.syrjala@linux.intel.com
Reviewed-by: Imre Deak <imre.deak@intel.com>

diff --git a/drivers/gpu/drm/i915/display/intel_fbc.c b/drivers/gpu/drm/i915/display/intel_fbc.c
index 6f1d5c032681fcb44f46453e61c684cae57505f7..a1048ece541e2ebdb33fb327cf2c7d8dbdf65760 100644 (file)
--- 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;