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

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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 <michel@xxxxxxxxxxx> 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
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