From: Badal Nilawar <badal.nilawar@xxxxxxxxx> [ Upstream commit 22ef43c78647dd37b0dafe2182b8650b99dbbe59 ] 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 (cherry picked from commit e5152723380404acb8175e0777b1cea57f319a01) Signed-off-by: Lucas De Marchi <lucas.demarchi@xxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/gpu/drm/xe/xe_guc_ct.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c index cd9918e3896c0..ab24053f8766f 100644 --- a/drivers/gpu/drm/xe/xe_guc_ct.c +++ b/drivers/gpu/drm/xe/xe_guc_ct.c @@ -888,6 +888,24 @@ static int guc_ct_send_recv(struct xe_guc_ct *ct, const u32 *action, u32 len, ret = wait_event_timeout(ct->g2h_fence_wq, g2h_fence.done, HZ); + /* + * 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 -- 2.43.0
