drm/i915/guc: Stop using fence/status from CTB descriptor

Stop using fence/status from CTB descriptor as future GuC ABI will
no longer support replies over CTB descriptor.
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20210603051630.2635-8-matthew.brost@intel.com

drivers/gpu/drm/i915/gt/uc/abi/guc_communication_ctb_abi.h

@@ -71,8 +71,8 @@ struct guc_ct_buffer_desc {
 	u32 head;		/* offset updated by GuC*/
 	u32 tail;		/* offset updated by owner */
 	u32 is_in_error;	/* error indicator */
-	u32 fence;		/* fence updated by GuC */
-	u32 status;		/* status updated by GuC */
+	u32 reserved1;
+	u32 reserved2;
 	u32 owner;		/* id of the channel owner */
 	u32 owner_sub_id;	/* owner-defined field for extra tracking */
 	u32 reserved[5];

drivers/gpu/drm/i915/gt/uc/intel_guc_ct.c

@@ -90,13 +90,6 @@ static void guc_ct_buffer_desc_init(struct guc_ct_buffer_desc *desc,
 	desc->owner = CTB_OWNER_HOST;
 }
 
-static void guc_ct_buffer_desc_reset(struct guc_ct_buffer_desc *desc)
-{
-	desc->head = 0;
-	desc->tail = 0;
-	desc->is_in_error = 0;
-}
-
 static int guc_action_register_ct_buffer(struct intel_guc *guc,
 					 u32 desc_addr,
 					 u32 type)
@@ -315,8 +308,7 @@ static u32 ct_get_next_fence(struct intel_guc_ct *ct)
 static int ct_write(struct intel_guc_ct *ct,
 		    const u32 *action,
 		    u32 len /* in dwords */,
-		    u32 fence,
-		    bool want_response)
+		    u32 fence)
 {
 	struct intel_guc_ct_buffer *ctb = &ct->ctbs[CTB_SEND];
 	struct guc_ct_buffer_desc *desc = ctb->desc;
@@ -360,8 +352,7 @@ static int ct_write(struct intel_guc_ct *ct,
 	 * DW2+: action data
 	 */
 	header = (len << GUC_CT_MSG_LEN_SHIFT) |
-		 (GUC_CT_MSG_WRITE_FENCE_TO_DESC) |
-		 (want_response ? GUC_CT_MSG_SEND_STATUS : 0) |
+		 GUC_CT_MSG_SEND_STATUS |
 		 (action[0] << GUC_CT_MSG_ACTION_SHIFT);
 
 	CT_DEBUG(ct, "writing %*ph %*ph %*ph\n",
@@ -390,56 +381,6 @@ static int ct_write(struct intel_guc_ct *ct,
 	return -EPIPE;
 }
 
-/**
- * wait_for_ctb_desc_update - Wait for the CT buffer descriptor update.
- * @desc:	buffer descriptor
- * @fence:	response fence
- * @status:	placeholder for status
- *
- * Guc will update CT buffer descriptor with new fence and status
- * after processing the command identified by the fence. Wait for
- * specified fence and then read from the descriptor status of the
- * command.
- *
- * Return:
- * *	0 response received (status is valid)
- * *	-ETIMEDOUT no response within hardcoded timeout
- * *	-EPROTO no response, CT buffer is in error
- */
-static int wait_for_ctb_desc_update(struct guc_ct_buffer_desc *desc,
-				    u32 fence,
-				    u32 *status)
-{
-	int err;
-
-	/*
-	 * Fast commands should complete in less than 10us, so sample quickly
-	 * up to that length of time, then switch to a slower sleep-wait loop.
-	 * No GuC command should ever take longer than 10ms.
-	 */
-#define done (READ_ONCE(desc->fence) == fence)
-	err = wait_for_us(done, 10);
-	if (err)
-		err = wait_for(done, 10);
-#undef done
-
-	if (unlikely(err)) {
-		DRM_ERROR("CT: fence %u failed; reported fence=%u\n",
-			  fence, desc->fence);
-
-		if (WARN_ON(desc->is_in_error)) {
-			/* Something went wrong with the messaging, try to reset
-			 * the buffer and hope for the best
-			 */
-			guc_ct_buffer_desc_reset(desc);
-			err = -EPROTO;
-		}
-	}
-
-	*status = desc->status;
-	return err;
-}
-
 /**
  * wait_for_ct_request_update - Wait for CT request state update.
  * @req:	pointer to pending request
@@ -483,8 +424,6 @@ static int ct_send(struct intel_guc_ct *ct,
 		   u32 response_buf_size,
 		   u32 *status)
 {
-	struct intel_guc_ct_buffer *ctb = &ct->ctbs[CTB_SEND];
-	struct guc_ct_buffer_desc *desc = ctb->desc;
 	struct ct_request request;
 	unsigned long flags;
 	u32 fence;
@@ -505,16 +444,13 @@ static int ct_send(struct intel_guc_ct *ct,
 	list_add_tail(&request.link, &ct->requests.pending);
 	spin_unlock_irqrestore(&ct->requests.lock, flags);
 
-	err = ct_write(ct, action, len, fence, !!response_buf);
+	err = ct_write(ct, action, len, fence);
 	if (unlikely(err))
 		goto unlink;
 
 	intel_guc_notify(ct_to_guc(ct));
 
-	if (response_buf)
 	err = wait_for_ct_request_update(&request, status);
-	else
-		err = wait_for_ctb_desc_update(desc, fence, status);
 	if (unlikely(err))
 		goto unlink;