This is a note to let you know that I've just added the patch titled
drm/xe/guc/ct: Flush g2h worker in case of g2h response timeout
to the 6.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
drm-xe-guc-ct-flush-g2h-worker-in-case-of-g2h-respon.patch
and it can be found in the queue-6.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 72c96519d298b651014f1f2803a257b6071ffc7f
Author: Badal Nilawar <badal.nilawar@xxxxxxxxx>
Date: Thu Oct 17 16:44:10 2024 +0530
drm/xe/guc/ct: Flush g2h worker in case of g2h response timeout
[ Upstream commit e5152723380404acb8175e0777b1cea57f319a01 ]
In case if g2h worker doesn't get opportunity to within specified
timeout delay then flush the g2h worker explicitly.
v2:
- Describe change in the comment and add TODO (Matt B/John H)
- Add xe_gt_warn on fence done after G2H flush (John H)
v3:
- Updated the comment with root cause
- Clean up xe_gt_warn message (John H)
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/issues/1620
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/issues/2902
Signed-off-by: Badal Nilawar <badal.nilawar@xxxxxxxxx>
Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
Cc: John Harrison <John.C.Harrison@xxxxxxxxx>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@xxxxxxxxx>
Reviewed-by: Himal Prasad Ghimiray <himal.prasad.ghimiray@xxxxxxxxx>
Acked-by: Matthew Brost <matthew.brost@xxxxxxxxx>
Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20241017111410.2553784-2-badal.nilawar@xxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
index 9c505d3517cd1..cd6a5f09d631e 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -906,6 +906,24 @@ static int guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len,
}
}
+ /*
+ * Occasionally it is seen that the G2H worker starts running after a delay of more than
+ * a second even after being queued and activated by the Linux workqueue subsystem. This
+ * leads to G2H timeout error. The root cause of issue lies with scheduling latency of
+ * Lunarlake Hybrid CPU. Issue dissappears if we disable Lunarlake atom cores from BIOS
+ * and this is beyond xe kmd.
+ *
+ * TODO: Drop this change once workqueue scheduling delay issue is fixed on LNL Hybrid CPU.
+ */
+ if (!ret) {
+ flush_work(&ct->g2h_worker);
+ if (g2h_fence.done) {
+ xe_gt_warn(gt, "G2H fence %u, action %04x, done\n",
+ g2h_fence.seqno, action[0]);
+ ret = 1;
+ }
+ }
+
/*
* Ensure we serialize with completion side to prevent UAF with fence going out of scope on
* the stack, since we have no clue if it will fire after the timeout before we can erase
