drm/radeon/kms/r7xx: add workaround for hw issue with HDP flush
Use of HDP_*_COHERENCY_FLUSH_CNTL can cause a hang in certain
situations. Add workaround.
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Cc: stable@kernel.org
Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/rv770.c b/drivers/gpu/drm/radeon/rv770.c
index 236fe66..f1c79681 100644
--- a/drivers/gpu/drm/radeon/rv770.c
+++ b/drivers/gpu/drm/radeon/rv770.c
@@ -204,7 +204,10 @@
WREG32((0x2c20 + j), 0x00000000);
WREG32((0x2c24 + j), 0x00000000);
}
- WREG32(HDP_REG_COHERENCY_FLUSH_CNTL, 0);
+ /* r7xx hw bug. Read from HDP_DEBUG1 rather
+ * than writing to HDP_REG_COHERENCY_FLUSH_CNTL
+ */
+ tmp = RREG32(HDP_DEBUG1);
rv515_mc_stop(rdev, &save);
if (r600_mc_wait_for_idle(rdev)) {