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drm/i915/fbc: Reject PLANE_OFFSET.y%4!=0 on icl+ too
authorVille Syrjälä <ville.syrjala@linux.intel.com>
Fri, 13 Dec 2019 13:34:48 +0000 (15:34 +0200)
committerVille Syrjälä <ville.syrjala@linux.intel.com>
Thu, 19 Dec 2019 20:18:26 +0000 (22:18 +0200)
commit317b2cac79a66c7156dbe7983b825dc417acf9a8
tree90a497c94718e0328d41e37b4bbcb30773ab3a92
parente1f0fbda75e6447077205b472d1dd71bef417a4c
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>
drivers/gpu/drm/i915/display/intel_fbc.c