Is it better to enable SWIOTLB? Are there any advantages with SWIOTLB enabled?
— Christian
Sent from my iPhone
> On 27. Nov 2017, at 15:53, Michel Dänzer <mic...@daenzer.net> wrote:
>
>> 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
_______________________________________________
dri-devel mailing list
dri-devel@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/dri-devel
