[PATCH] drm/amdgpu: wait for all rings to drain before runtime suspending

[Christian König]

Am 11.12.19 um 03:26 schrieb zhoucm1:
>
> On 2019/12/11 上午6:08, Alex Deucher wrote:
>> Add a safety check to runtime suspend to make sure all outstanding
>> fences have signaled before we suspend.  Doesn't fix any known issue.
>>
>> We already do this via the fence driver suspend function, but we
>> just force completion rather than bailing.  This bails on runtime
>> suspend so we can try again later once the fences are signaled to
>> avoid missing any outstanding work.
>
> The idea sounds OK to me, but if you want to drain the rings, you 
> should make sure no more submission, right?
>
> So you should park all schedulers before waiting for all outstanding 
> fences completed.

At that point userspace should already be put to hold, so no new 
submissions. But it probably won't hurt stopping the scheduler anyway.

But another issue I see is what happens if we locked up the hardware?

Christian.

>
> -David
>
>>
>> Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 12 +++++++++++-
>>   1 file changed, 11 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>> index 2f367146c72c..81322b0a8acf 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>> @@ -1214,13 +1214,23 @@ static int 
>> amdgpu_pmops_runtime_suspend(struct device *dev)
>>       struct pci_dev *pdev = to_pci_dev(dev);
>>       struct drm_device *drm_dev = pci_get_drvdata(pdev);
>>       struct amdgpu_device *adev = drm_dev->dev_private;
>> -    int ret;
>> +    int ret, i;
>>         if (!adev->runpm) {
>>           pm_runtime_forbid(dev);
>>           return -EBUSY;
>>       }
>>   +    /* wait for all rings to drain before suspending */
>> +    for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
>> +        struct amdgpu_ring *ring = adev->rings[i];
>> +        if (ring && ring->sched.ready) {
>> +            ret = amdgpu_fence_wait_empty(ring);
>> +            if (ret)
>> +                return -EBUSY;
>> +        }
>> +    }
>> +
>>       if (amdgpu_device_supports_boco(drm_dev))
>>           drm_dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
>>       drm_kms_helper_poll_disable(drm_dev);
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