[PATCH] drm/amdgpu/gmc6: fix DMA mask

[Paul Menzel]

Dear Alex,


On 28.10.21 10:32, Paul Menzel wrote:

> On 28.10.21 00:19, Paul Menzel wrote:
> 
>> On 27.10.21 20:23, Alex Deucher wrote:
>>> On Wed, Oct 27, 2021 at 2:22 PM Alex Deucher wrote:
>>>>
>>>> The DMA mask on SI parts is 40 bits not 44.  Looks like a copy
>>>> paste typo.
>>>
>>> Bug: https://gitlab.freedesktop.org/drm/amd/-/issues/1762
>>>
>>> Fixed locally.
>>
>> As I have no way to reproduce this, as the ring gfx timeout error is 
>> logged ten seconds after the IO_PAGE_FAULT, is very likely to be related?
>>
>> Hopefully I am going to be able to test this on Friday. Does AMD’s QA 
>> team have the cards to test the `iommu.forcedac=1` case? Is that test 
>> case going to be added to the “test protocol”?
>>
>> Lastly, should a Fixes tag be added, so it’s picked up for the stable 
>> series?
> 
> Does the value of 44 need to be changed to 40 also five lines below?
> 
> -       adev->need_swiotlb = drm_need_swiotlb(44);
> +       adev->need_swiotlb = drm_need_swiotlb(40);

I booted the Dell OptiPlex 5055 with this patch (both hunks) on top of 
commit 1fc596a56b (Merge tag 'trace-v5.15-rc6' of 
git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace) with 
`iommu.forcedac=1`, and did not get any errors.

Tested-by: Paul Menzel <pmenzel at molgen.mpg.de> (AMD OptiPlex 5055, 
Radeon HD 8570 / R7 240/340 OEM, 1002:6611 with `iommu.forcedac=1`)

Maybe in the commit message summary extend: Fix DMA mask from 44 to 40.


Kind regards,

Paul