[PATCH 1/1] drm/amdgpu: return early on error while setting bar0 memtype

[Christian König]

Am 02.11.21 um 11:11 schrieb Das, Nirmoy:
>
> On 11/2/2021 9:00 AM, Lazar, Lijo wrote:
>>
>>
>> On 10/29/2021 8:39 PM, Nirmoy Das wrote:
>>> We set WC memtype for aper_base but don't check return value
>>> of arch_io_reserve_memtype_wc(). Be more defensive and return
>>> early on error.
>>>
>>> Signed-off-by: Nirmoy Das <nirmoy.das at amd.com>
>>> ---
>>>   drivers/gpu/drm/amd/amdgpu/amdgpu_object.c | 7 ++++++-
>>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c 
>>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>>> index 073ba2af0b9c..6b25982a9077 100644
>>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
>>> @@ -1032,9 +1032,14 @@ int amdgpu_bo_init(struct amdgpu_device *adev)
>>>       /* On A+A platform, VRAM can be mapped as WB */
>>>       if (!adev->gmc.xgmi.connected_to_cpu) {
>>>           /* reserve PAT memory space to WC for VRAM */
>>> -        arch_io_reserve_memtype_wc(adev->gmc.aper_base,
>>> +        int r = arch_io_reserve_memtype_wc(adev->gmc.aper_base,
>>>                   adev->gmc.aper_size);
>>
>> BTW, isn't it more appropriate to use visible vram size? There are 
>> cases where pci resize rounds aperture to the next higher size > size 
>> of actual VRAM.
>
>
> Good point, I will update this one and send again.

Not a good idea at all.

The aperture size is rounded up to the next power of two and that's 
exactly what we should stick to if we don't want to get an error code in 
return.

Regards,
Christian.

>
>
> Regards,
>
> Nirmoy
>
>
>>
>> Thanks,
>> Lijo
>>>   +        if (r) {
>>> +            DRM_ERROR("Unable to set WC memtype for the aperture 
>>> base\n");
>>> +            return r;
>>> +        }
>>> +
>>>           /* Add an MTRR for the VRAM */
>>>           adev->gmc.vram_mtrr = arch_phys_wc_add(adev->gmc.aper_base,
>>>                   adev->gmc.aper_size);
>>>