diff options
author | Ben Skeggs <bskeggs@redhat.com> | 2017-05-11 17:19:48 +1000 |
---|---|---|
committer | Ben Skeggs <bskeggs@redhat.com> | 2017-05-12 08:32:57 +1000 |
commit | 1b0f84380b10ee97f7d2dd191294de9017e94d1d (patch) | |
tree | 0507437bc996484f39ef8290358ec60da67a49fd /drivers/gpu | |
parent | 3733bd8b407211739e72d051e5f30ad82a52c4bc (diff) |
drm/nouveau/tmr: handle races with hw when updating the next alarm time
If the time to the next alarm is short enough, we could race with HW and
end up with an ~4 second delay until it triggers.
Fix this by checking again after we update HW.
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>
Cc: stable@vger.kernel.org
Diffstat (limited to 'drivers/gpu')
-rw-r--r-- | drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c | 26 |
1 files changed, 16 insertions, 10 deletions
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c index 07dc82bfe346..4e696627fdcd 100644 --- a/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c @@ -36,23 +36,29 @@ nvkm_timer_alarm_trigger(struct nvkm_timer *tmr) unsigned long flags; LIST_HEAD(exec); - /* move any due alarms off the pending list */ + /* Process pending alarms. */ spin_lock_irqsave(&tmr->lock, flags); list_for_each_entry_safe(alarm, atemp, &tmr->alarms, head) { - if (alarm->timestamp <= nvkm_timer_read(tmr)) - list_move_tail(&alarm->head, &exec); + /* Have we hit the earliest alarm that hasn't gone off? */ + if (alarm->timestamp > nvkm_timer_read(tmr)) { + /* Schedule it. If we didn't race, we're done. */ + tmr->func->alarm_init(tmr, alarm->timestamp); + if (alarm->timestamp > nvkm_timer_read(tmr)) + break; + } + + /* Move to completed list. We'll drop the lock before + * executing the callback so it can reschedule itself. + */ + list_move_tail(&alarm->head, &exec); } - /* reschedule interrupt for next alarm time */ - if (!list_empty(&tmr->alarms)) { - alarm = list_first_entry(&tmr->alarms, typeof(*alarm), head); - tmr->func->alarm_init(tmr, alarm->timestamp); - } else { + /* Shut down interrupt if no more pending alarms. */ + if (list_empty(&tmr->alarms)) tmr->func->alarm_fini(tmr); - } spin_unlock_irqrestore(&tmr->lock, flags); - /* execute any pending alarm handlers */ + /* Execute completed callbacks. */ list_for_each_entry_safe(alarm, atemp, &exec, head) { list_del_init(&alarm->head); alarm->func(alarm); |