drm/radeon/kms: properly compute group_size on 6xx/7xx

Needed for tiled surfaces.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/radeon/r600.c

@@ -1608,8 +1608,11 @@ void r600_gpu_init(struct radeon_device *rdev)
 	rdev->config.r600.tiling_npipes = rdev->config.r600.max_tile_pipes;
 	rdev->config.r600.tiling_nbanks = 4 << ((ramcfg & NOOFBANK_MASK) >> NOOFBANK_SHIFT);
 	tiling_config |= BANK_TILING((ramcfg & NOOFBANK_MASK) >> NOOFBANK_SHIFT);
-	tiling_config |= GROUP_SIZE(0);
-	rdev->config.r600.tiling_group_size = 256;
+	tiling_config |= GROUP_SIZE((ramcfg & BURSTLENGTH_MASK) >> BURSTLENGTH_SHIFT);
+	if ((ramcfg & BURSTLENGTH_MASK) >> BURSTLENGTH_SHIFT)
+		rdev->config.r600.tiling_group_size = 512;
+	else
+		rdev->config.r600.tiling_group_size = 256;
 	tmp = (ramcfg & NOOFROWS_MASK) >> NOOFROWS_SHIFT;
 	if (tmp > 3) {
 		tiling_config |= ROW_TILING(3);

drivers/gpu/drm/radeon/rv770.c

@@ -644,10 +644,11 @@ static void rv770_gpu_init(struct radeon_device *rdev)
 	else
 		gb_tiling_config |= BANK_TILING((mc_arb_ramcfg & NOOFBANK_MASK) >> NOOFBANK_SHIFT);
 	rdev->config.rv770.tiling_nbanks = 4 << ((gb_tiling_config >> 4) & 0x3);
-
-	gb_tiling_config |= GROUP_SIZE(0);
-	rdev->config.rv770.tiling_group_size = 256;
-
+	gb_tiling_config |= GROUP_SIZE((mc_arb_ramcfg & BURSTLENGTH_MASK) >> BURSTLENGTH_SHIFT);
+	if ((mc_arb_ramcfg & BURSTLENGTH_MASK) >> BURSTLENGTH_SHIFT)
+		rdev->config.rv770.tiling_group_size = 512;
+	else
+		rdev->config.rv770.tiling_group_size = 256;
 	if (((mc_arb_ramcfg & NOOFROWS_MASK) >> NOOFROWS_SHIFT) > 3) {
 		gb_tiling_config |= ROW_TILING(3);
 		gb_tiling_config |= SAMPLE_SPLIT(3);