From 330bdf62fe6a6c5b99a647f7bf7157107c9348b3 Mon Sep 17 00:00:00 2001 From: Ben Skeggs Date: Thu, 11 May 2017 17:13:29 +1000 Subject: [PATCH] drm/nouveau/tmr: avoid processing completed alarms when adding a new one 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 Cc: stable@vger.kernel.org --- drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c index d898787d514c..f2a86eae0a0d 100644 --- a/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/timer/base.c @@ -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 -- 2.30.2