Re: [PATCH v3 5/5] drm/amdgpu: do not resume device in thaw for normal hibernation

[Mario Limonciello <mario.limonciello@amd.com>]

On 7/8/2025 12:08 PM, Zhang, GuoQing (Sam) wrote:
> 
> On 2025/7/8 22:40, Mario Limonciello wrote:
>> On 7/8/2025 3:42 AM, Samuel Zhang wrote:
>>> For normal hibernation, GPU do not need to be resumed in thaw since 
>>> it is
>>> not involved in writing the hibernation image. Skip resume in this case
>>> can reduce the hibernation time.
>>>
>>> On VM with 8 * 192GB VRAM dGPUs, 98% VRAM usage and 1.7TB system memory,
>>> this can save 50 minutes.
>>
>> If I'm not mistaken this will also have the side effect that display 
>> is not resumed in the "normal case" too, right?
> 
> 
> Yes, I believe so.
> 
> 
>>
>> I know the GPU you used doesn't have a display, but I'm just thinking 
>> about the callpaths and implications.
>>
>> Would you be able to test this series specifically on an APU with a 
>> display connected to eDP and no compositor running (so no DRM master) 
>> to make sure it works as intended?
> 
> 
> Sorry, Mario. I don't have such APU environment to test this behavior.
> 

OK, let me see if I can get someone to test this for you.  Will let you 
know any problems.

> Regards
> Sam
> 
> 
>>
>>>
>>> Signed-off-by: Samuel Zhang <guoqing.zhang@amd.com>
>>> ---
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c | 15 ++++++++++++++-
>>>   1 file changed, 14 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c b/drivers/gpu/ 
>>> drm/amd/amdgpu/amdgpu_drv.c
>>> index 4f8632737574..10827becf855 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
>>> @@ -2541,6 +2541,10 @@ amdgpu_pci_shutdown(struct pci_dev *pdev)
>>>       if (amdgpu_ras_intr_triggered())
>>>           return;
>>>   +    /* device maybe not resumed here, return immediately in this 
>>> case */
>>> +    if (adev->in_s4 && adev->in_suspend)
>>> +        return;
>>> +
>>>       /* if we are running in a VM, make sure the device
>>>        * torn down properly on reboot/shutdown.
>>>        * unfortunately we can't detect certain
>>> @@ -2654,8 +2658,17 @@ static int amdgpu_pmops_freeze(struct device 
>>> *dev)
>>>   static int amdgpu_pmops_thaw(struct device *dev)
>>>   {
>>>       struct drm_device *drm_dev = dev_get_drvdata(dev);
>>> +    int event = pm_transition_event();
>>>   -    return amdgpu_device_resume(drm_dev, true);
>>> +    switch (event) {
>>> +    case PM_EVENT_THAW: /* normal case */
>>> +        return 0;
>>> +    case PM_EVENT_RECOVER: /* error case */
>>> +        return amdgpu_device_resume(drm_dev, true);
>>> +    default:
>>> +        pr_err("unknown pm_transition_event %d\n", event);
>>> +        return -EOPNOTSUPP;
>>> +    }
>>>   }
>>>     static int amdgpu_pmops_poweroff(struct device *dev)
>>