[PATCH 6.18 0976/1611] drm/panthor: Dont overrule pending immediate ticks in sched_resume_tick()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Boris Brezillon <boris.brezillon@collabora.com>

[ Upstream commit 6fec8b473497b7f32e604a6dd92b32b0889af3e8 ]

We schedule immediate ticks when we need to process events on CSGs,
but those immediate ticks don't change the resched_target because we
want the other groups to stay scheduled for the remaining of the GPU
timeslot they were given. Make sure these immediate ticks don't get
overruled by a sched_queue_delayed_work() that would delay the tick
execution.

Fixes: 99820b4b7e50 ("drm/panthor: Make sure we resume the tick when new jobs are submitted")
Reported-by: sashiko-bot@kernel.org
Closes: https://sashiko.dev/#/patchset/20260625-panthor-signal-from-irq-v4-0-3d2908912afa@collabora.com?part=9
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Karunika Choo <karunika.choo@arm.com>
Signed-off-by: Liviu Dudau <liviu.dudau@arm.com>
Link: https://patch.msgid.link/20260625-panthor-misc-fixes-v1-6-b67ed973fea6@collabora.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/panthor/panthor_sched.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panthor/panthor_sched.c b/drivers/gpu/drm/panthor/panthor_sched.c
index 749fe34b06db28..ff6fb8e6c38e96 100644
--- a/drivers/gpu/drm/panthor/panthor_sched.c
+++ b/drivers/gpu/drm/panthor/panthor_sched.c
@@ -2588,7 +2588,14 @@ static void sched_resume_tick(struct panthor_device *ptdev)
 	else
 		delay_jiffies = 0;
 
-	sched_queue_delayed_work(sched, tick, delay_jiffies);
+	/* We schedule immediate ticks when we need to process events on CSGs,
+	 * but those don't change the resched_target because we want the other
+	 * groups to stay scheduled for the remaining of the GPU timeslot they
+	 * were given. Make sure those immediate ticks don't get overruled by
+	 * a sched_queue_delayed_work() that would delay the tick execution.
+	 */
+	if (!delayed_work_pending(&sched->tick_work))
+		sched_queue_delayed_work(sched, tick, delay_jiffies);
 }
 
 static void group_schedule_locked(struct panthor_group *group, u32 queue_mask)
-- 
2.53.0