[Intel-gfx] [PATCH v3 3/7] drm/i915/guc: remove writes to GEN8_DRBREG registers

[Dave Gordon]

These registers are not actually writable by the CPU; only the GuC can
actually program them. So let's not do writes that have no effect.

Signed-off-by: Dave Gordon <david.s.gordon at intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
---
 drivers/gpu/drm/i915/i915_guc_submission.c | 5 -----
 1 file changed, 5 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index 21daaa5..1589fe9 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -252,14 +252,9 @@ static void guc_disable_doorbell(struct intel_guc *guc,
 
 	doorbell->db_status = GUC_DOORBELL_DISABLED;
 
-	I915_WRITE(drbreg, I915_READ(drbreg) & ~GEN8_DRB_VALID);
-
 	value = I915_READ(drbreg);
 	WARN_ON((value & GEN8_DRB_VALID) != 0);
 
-	I915_WRITE(GEN8_DRBREGU(client->doorbell_id), 0);
-	I915_WRITE(drbreg, 0);
-
 	/* XXX: wait for any interrupts */
 	/* XXX: wait for workqueue to drain */
 }
-- 
1.9.1