Doorbell release flow requires that we wait for GEN8_DRB_VALID bit to go
to zero after updating db_status before we call the GuC to release the
doorbell.
Kudos to Daniele for finding this out.
v2: WARN instead of DRM_ERROR (Joonas)
Signed-off-by: Oscar Mateo <oscar.mateo@xxxxxxxxx>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@xxxxxxxxx>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/i915_guc_submission.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
index c02167c..2d4d854 100644
--- a/drivers/gpu/drm/i915/i915_guc_submission.c
+++ b/drivers/gpu/drm/i915/i915_guc_submission.c
@@ -206,12 +206,22 @@ static int __create_doorbell(struct i915_guc_client *client)
static int __destroy_doorbell(struct i915_guc_client *client)
{
+ struct drm_i915_private *dev_priv = guc_to_i915(client->guc);
struct guc_doorbell_info *doorbell;
+ u16 db_id = client->doorbell_id;
+
+ GEM_BUG_ON(db_id >= GUC_DOORBELL_INVALID);
doorbell = __get_doorbell(client);
doorbell->db_status = GUC_DOORBELL_DISABLED;
doorbell->cookie = 0;
+ /* Doorbell release flow requires that we wait for GEN8_DRB_VALID bit
+ * to go to zero after updating db_status before we call the GuC to
+ * release the doorbell */
+ if (wait_for_us(!(I915_READ(GEN8_DRBREGL(db_id)) & GEN8_DRB_VALID), 10))
+ WARN_ONCE(true, "Doorbell never became invalid after disable\n");
+
return __guc_deallocate_doorbell(client->guc, client->ctx_index);
}
--
1.9.1
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