drm/radeon/kms: allow rendering while no colorbuffer is set on r300
Because hardware cannot disable all colorbuffers directly to do depth-only
rendering, a user should:
- disable reading from a colorbuffer in blending
- disable fastfill
- set the color channel mask to 0 to prevent writing to a colorbuffer
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/r300.c b/drivers/gpu/drm/radeon/r300.c
index 83490c2..6a5d117 100644
--- a/drivers/gpu/drm/radeon/r300.c
+++ b/drivers/gpu/drm/radeon/r300.c
@@ -992,6 +992,18 @@
}
ib[idx] = idx_value + ((u32)reloc->lobj.gpu_offset);
break;
+ case 0x4e0c:
+ /* RB3D_COLOR_CHANNEL_MASK */
+ track->color_channel_mask = idx_value;
+ break;
+ case 0x4d1c:
+ /* ZB_BW_CNTL */
+ track->fastfill = !!(idx_value & (1 << 2));
+ break;
+ case 0x4e04:
+ /* RB3D_BLENDCNTL */
+ track->blend_read_enable = !!(idx_value & (1 << 2));
+ break;
case 0x4be8:
/* valid register only on RV530 */
if (p->rdev->family == CHIP_RV530)