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

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Message-ID: <1214642e-73d6-4916-8578-8cb40b846d42@amd.com>
Date: Wed, 9 Jul 2025 00:08:09 +0800
From: "Zhang, GuoQing (Sam)" <guoqzhan@....com>
To: Mario Limonciello <mario.limonciello@....com>, Samuel Zhang
	<guoqing.zhang@....com>, <alexander.deucher@....com>,
	<christian.koenig@....com>, <rafael@...nel.org>, <len.brown@...el.com>,
	<pavel@...nel.org>, <gregkh@...uxfoundation.org>, <dakr@...nel.org>,
	<airlied@...il.com>, <simona@...ll.ch>, <ray.huang@....com>,
	<matthew.auld@...el.com>, <matthew.brost@...el.com>,
	<maarten.lankhorst@...ux.intel.com>, <mripard@...nel.org>,
	<tzimmermann@...e.de>
CC: <lijo.lazar@....com>, <victor.zhao@....com>, <haijun.chang@....com>,
	<Qing.Ma@....com>, <Owen.Zhang2@....com>, <linux-pm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <amd-gfx@...ts.freedesktop.org>,
	<dri-devel@...ts.freedesktop.org>
Subject: Re: [PATCH v3 5/5] drm/amdgpu: do not resume device in thaw for
 normal hibernation


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.

Regards
Sam


>
>>
>> Signed-off-by: Samuel Zhang <guoqing.zhang@....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)
>