[PATCH 08/28] drm/xe: Don't change LRC ring head on job resubmission

[Matthew Brost <matthew.brost@intel.com>]

Now that we save the job's head during submission, it's no longer
necessary to adjust the LRC ring head during resubmission. Instead, a
software-based adjustment of the tail will overwrite the old jobs in
place. For some odd reason, adjusting the LRC ring head didn't work on
parallel queues, which was causing issues in our CI.

v6:
 - Also set LRC tail to head so queue is idle coming out of reset

Signed-off-by: Matthew Brost <matthew.brost@intel.com>
---
 drivers/gpu/drm/xe/xe_guc_submit.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
index 774c4bbd4cc4..c7ccdcf22196 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1998,11 +1998,17 @@ static void guc_exec_queue_start(struct xe_exec_queue *q)
 	struct xe_gpu_scheduler *sched = &q->guc->sched;
 
 	if (!exec_queue_killed_or_banned_or_wedged(q)) {
+		struct xe_sched_job *job = xe_sched_first_pending_job(sched);
 		int i;
 
 		trace_xe_exec_queue_resubmit(q);
-		for (i = 0; i < q->width; ++i)
-			xe_lrc_set_ring_head(q->lrc[i], q->lrc[i]->ring.tail);
+		if (job) {
+			for (i = 0; i < q->width; ++i) {
+				q->lrc[i]->ring.tail = job->ptrs[i].head;
+				xe_lrc_set_ring_tail(q->lrc[i],
+						     xe_lrc_ring_head(q->lrc[i]));
+			}
+		}
 		xe_sched_resubmit_jobs(sched);
 	}
 
-- 
2.34.1