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SubjectRe: [PATCH 1/2] drm/msm: Move hangcheck timer restart
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On 8/4/2022 1:59 AM, Rob Clark wrote:
> On Wed, Aug 3, 2022 at 12:52 PM Akhil P Oommen <quic_akhilpo@quicinc.com> wrote:
>> On 8/3/2022 10:53 PM, Rob Clark wrote:
>>> From: Rob Clark <robdclark@chromium.org>
>>>
>>> Don't directly restart the hangcheck timer from the timer handler, but
>>> instead start it after the recover_worker replays remaining jobs.
>>>
>>> If the kthread is blocked for other reasons, there is no point to
>>> immediately restart the timer. Fixes a random symptom of the problem
>>> fixed in the next patch.
>>>
>>> Signed-off-by: Rob Clark <robdclark@chromium.org>
>>> ---
>>> drivers/gpu/drm/msm/msm_gpu.c | 14 +++++++++-----
>>> 1 file changed, 9 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/msm/msm_gpu.c b/drivers/gpu/drm/msm/msm_gpu.c
>>> index fba85f894314..8f9c48eabf7d 100644
>>> --- a/drivers/gpu/drm/msm/msm_gpu.c
>>> +++ b/drivers/gpu/drm/msm/msm_gpu.c
>>> @@ -328,6 +328,7 @@ find_submit(struct msm_ringbuffer *ring, uint32_t fence)
>>> }
>>>
>>> static void retire_submits(struct msm_gpu *gpu);
>>> +static void hangcheck_timer_reset(struct msm_gpu *gpu);
>>>
>>> static void get_comm_cmdline(struct msm_gem_submit *submit, char **comm, char **cmd)
>>> {
>>> @@ -420,6 +421,8 @@ static void recover_worker(struct kthread_work *work)
>>> }
>>>
>>> if (msm_gpu_active(gpu)) {
>>> + bool restart_hangcheck = false;
>>> +
>>> /* retire completed submits, plus the one that hung: */
>>> retire_submits(gpu);
>>>
>>> @@ -436,10 +439,15 @@ static void recover_worker(struct kthread_work *work)
>>> unsigned long flags;
>>>
>>> spin_lock_irqsave(&ring->submit_lock, flags);
>>> - list_for_each_entry(submit, &ring->submits, node)
>>> + list_for_each_entry(submit, &ring->submits, node) {
>>> gpu->funcs->submit(gpu, submit);
>>> + restart_hangcheck = true;
>>> + }
>>> spin_unlock_irqrestore(&ring->submit_lock, flags);
>>> }
>>> +
>>> + if (restart_hangcheck)
>>> + hangcheck_timer_reset(gpu);
>>> }
>>>
>>> mutex_unlock(&gpu->lock);
>>> @@ -515,10 +523,6 @@ static void hangcheck_handler(struct timer_list *t)
>>> kthread_queue_work(gpu->worker, &gpu->recover_work);
>>> }
>>>
>>> - /* if still more pending work, reset the hangcheck timer: */
>> In the scenario mentioned here, shouldn't we restart the timer?
> yeah, actually the case where we don't want to restart the timer is
> *only* when we schedule recover_work..
>
> BR,
> -R
Not sure if your codebase is different but based on msm-next branch,
when "if (fence != ring->hangcheck_fence)" is true, we now skip
rescheduling the timer. I don't think that is what we want. There should
be a hangcheck timer running as long as there is an active submit,
unless we have scheduled a recover_work here.

-Akhil.
>
>> -Akhil.
>>> - if (fence_after(ring->fctx->last_fence, ring->hangcheck_fence))
>>> - hangcheck_timer_reset(gpu);
>>> -
>>> /* workaround for missing irq: */
>>> msm_gpu_retire(gpu);
>>> }
>>>

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