Hardware 3D acceleration doesn't work anymore with the latest git kernel

[Michel Dänzer]

On 2017-11-27 01:17 PM, Tom St Denis wrote:
> On 27/11/17 07:02 AM, Michel Dänzer wrote:
>> On 2017-11-27 12:50 PM, Christian König wrote:
>>> Am 27.11.2017 um 12:02 schrieb Michel Dänzer:
>>>> On 2017-11-24 05:09 PM, Michel Dänzer wrote:
>>>>> On 2017-11-24 03:29 PM, Christian Zigotzky wrote:
>>>>>> Hi All,
>>>>>>
>>>>>> I bisected today and the first bad commit is:
>>>>>> a4dec819c8bba6365eb893a4ca88db4dd1210110 (drm/ttm: Add helper
>>>>>> functions
>>>>>> to populate/map in one call (v2)) [1]
>>>>> It can't really be that commit, since it just adds functions but
>>>>> doesn't
>>>>> hook them up anywhere. Presumably it's commit
>>>>> f7871fd19389c5f64f625a4389675d0740f0dfe4 ("drm/radeon: use new TTM
>>>>> populate/dma map helper functions") instead, which makes the radeon
>>>>> driver rely on ttm_populate_and_map_pages, which is just a stub
>>>>> returning -ENOMEM when neither CONFIG_SWIOTLB nor
>>>>> CONFIG_INTEL_IOMMU is
>>>>> enabled.
>>>>>
>>>>> I can see two possible solutions:
>>>>>
>>>>> 1. Make ttm_populate_and_map_pages and ttm_unmap_and_unpopulate_pages
>>>>>      work without SWIOTLB / INTEL_IOMMU as well.
>>>>>
>>>>> 2. Make the drivers work without ttm_populate_and_map_pages and
>>>>>      ttm_unmap_and_unpopulate_pages again in that case.
>>>>>
>>>>>
>>>>> Solution 1 would be preferable.
>>>> Which solution do you want to go for?
>>>
>>> well, can somebody please explain to me why those patches actually
>>> result in problems?
>>
>> I thought I did above...
>>
>> Commit f7871fd19389c5f64f625a4389675d0740f0dfe4 made the radeon driver
>> rely on ttm_populate_and_map_pages, which is implemented as:
>>
>> static inline int ttm_populate_and_map_pages(struct device *dev,
>> struct ttm_dma_tt *tt)
>> {
>>     return -ENOMEM;
>> }
>>
>> when neither CONFIG_SWIOTLB nor CONFIG_INTEL_IOMMU is enabled.
>> Previously, the driver worked fine without either of those enabled.
>>
>>
> 
> I think the issue is why would you have both disabled [...]
Doesn't matter. The drivers worked with both disabled before, now they
don't. That's a regression.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer