According to Dave, once you've started an L2T flush, all L2T accesses
will be blocked until the flush completes. This fixes a consistent
3-4ms stall between the ioctl and running the job, and 3DMMES Taiji
goes from 27fps to 110fps.
v2: Leave a note about why we don't need to wait for completion.
Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
Fixes: 57692c94dcbe ("drm/v3d: Introduce a new DRM driver for Broadcom V3D V3.x+")
Reviewed-by: Dave Emett <david.emett@xxxxxxxxxxxx> (v1, comment requested)
---
drivers/gpu/drm/v3d/v3d_gem.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
index 01e879c71cad..c268c7c79566 100644
--- a/drivers/gpu/drm/v3d/v3d_gem.c
+++ b/drivers/gpu/drm/v3d/v3d_gem.c
@@ -143,13 +143,13 @@ v3d_invalidate_l2(struct v3d_dev *v3d, int core)
static void
v3d_flush_l2t(struct v3d_dev *v3d, int core)
{
+ /* While there is a busy bit (V3D_L2TCACTL_L2TFLS), we don't
+ * need to wait for completion before dispatching the job --
+ * L2T accesses will be stalled until the flush has completed.
+ */
V3D_CORE_WRITE(core, V3D_CTL_L2TCACTL,
V3D_L2TCACTL_L2TFLS |
V3D_SET_FIELD(V3D_L2TCACTL_FLM_FLUSH, V3D_L2TCACTL_FLM));
- if (wait_for(!(V3D_CORE_READ(core, V3D_CTL_L2TCACTL) &
- V3D_L2TCACTL_L2TFLS), 100)) {
- DRM_ERROR("Timeout waiting for L2T flush\n");
- }
}
/* Invalidates the slice caches. These are read-only caches. */
--
2.20.0.rc1
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