[PATCH 3/3] drm/amdgpu: move iommu_resume before ip init/resume

[James Zhu]

On 2021-09-07 12:48 p.m., Felix Kuehling wrote:
> Am 2021-09-07 um 12:07 p.m. schrieb James Zhu:
>> Separate iommu_resume from kfd_resume, and move it before
>> other amdgpu ip init/resume.
>>
>> Fixed Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211277
> I think the change is OK. But I don't understand how the IOMMUv2
> initialization sequence could affect a crash in DM. The display should
> not depend on IOMMUv2 at all. What am I missing?

[JZ] It is a weird issue. disable VCN IP block or disable gpu_off 
feature, or set pci=noats, all

can fix DM crash. Also the issue occurred quite random, some time after 
few suspend/resume cycle,

some times after few hundreds S/R cycles. the maximum that I saw is 2422 
S/R cycles.

But every time DM crash, I can see one or two iommu errors ahead:

*AMD-Vi: Event logged [IO_PAGE_FAULT domain=0x0000 address=**** 
flags=0x0070]*
Since we can't stop HW/FW/SW right the way after IO page fault detected, 
so I can't tell which part try to access
system memory through IOMMU.

But after moving IOMMU device init before other amdgpu IP init/resume, 
the DM crash /IOMMU page fault issues are gone.

Those patches can't directly explain why the issue fixed, but this new 
sequence makes more sense to me.

Can I have you RB on those patches?

Thanks!
James

>
> Regards,
>    Felix
>
>
>> Signed-off-by: James Zhu <James.Zhu at amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 12 ++++++++++++
>>   1 file changed, 12 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> index 653bd8f..e3f0308 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
>> @@ -2393,6 +2393,10 @@ static int amdgpu_device_ip_init(struct amdgpu_device *adev)
>>   	if (r)
>>   		goto init_failed;
>>   
>> +	r = amdgpu_amdkfd_resume_iommu(adev);
>> +	if (r)
>> +		goto init_failed;
>> +
>>   	r = amdgpu_device_ip_hw_init_phase1(adev);
>>   	if (r)
>>   		goto init_failed;
>> @@ -3147,6 +3151,10 @@ static int amdgpu_device_ip_resume(struct amdgpu_device *adev)
>>   {
>>   	int r;
>>   
>> +	r = amdgpu_amdkfd_resume_iommu(adev);
>> +	if (r)
>> +		return r;
>> +
>>   	r = amdgpu_device_ip_resume_phase1(adev);
>>   	if (r)
>>   		return r;
>> @@ -4602,6 +4610,10 @@ int amdgpu_do_asic_reset(struct list_head *device_list_handle,
>>   				dev_warn(tmp_adev->dev, "asic atom init failed!");
>>   			} else {
>>   				dev_info(tmp_adev->dev, "GPU reset succeeded, trying to resume\n");
>> +				r = amdgpu_amdkfd_resume_iommu(tmp_adev);
>> +				if (r)
>> +					goto out;
>> +
>>   				r = amdgpu_device_ip_resume_phase1(tmp_adev);
>>   				if (r)
>>   					goto out;
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