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drm/nouveau/tmr: avoid processing completed alarms when adding a new one

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The idea here was to avoid having to "manually" program the HW if there's
a new earliest alarm.  This was lazy and bad, as it leads to loads of fun
races between inter-related callers (ie. therm).

Turns out, it's not so difficult after all.  Go figure ;)

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Cc: stable@vger.kernel.org
This commit is contained in:
Ben Skeggs 2017-05-11 17:13:29 +10:00
parent 9fc64667ee
commit 330bdf62fe
1 changed files with 13 additions and 3 deletions
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16
drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c
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@ -86,12 +86,22 @@ nvkm_timer_alarm(struct nvkm_timer *tmr, u32 nsec, struct nvkm_alarm *alarm)
if (list->timestamp > alarm->timestamp)
break;
}
list_add_tail(&alarm->head, &list->head);
/* Update HW if this is now the earliest alarm. */
list = list_first_entry(&tmr->alarms, typeof(*list), head);
if (list == alarm) {
tmr->func->alarm_init(tmr, alarm->timestamp);
/* This shouldn't happen if callers aren't stupid.
*
* Worst case scenario is that it'll take roughly
* 4 seconds for the next alarm to trigger.
*/
WARN_ON(alarm->timestamp <= nvkm_timer_read(tmr));
}
}
spin_unlock_irqrestore(&tmr->lock, flags);
/* process pending alarms */
nvkm_timer_alarm_trigger(tmr);
}
void