On Wed, Feb 21, 2024 at 01:53:24PM +0100, Maxime Ripard wrote:
> Commit d393acce7b3f ("drm/tests: Switch to kunit devices") switched the
> DRM device creation helpers from an ad-hoc implementation to the new
> kunit device creation helpers introduced in commit d03c720e03bd ("kunit:
> Add APIs for managing devices").
>
> However, while the DRM helpers were using a platform_device, the kunit
> helpers are using a dedicated bus and device type.
>
> That situation creates small differences in the initialisation, and one
> of them is that the kunit devices do not have the DMA masks setup. In
> turn, this means that we can't do any kind of DMA buffer allocation
> anymore, which creates a regression on some (downstream for now) tests.
>
This is wrong. The mainline kernel crashes for me without this patch.
With v6.8-rc6:
[ 6.401720] ok 3 Above the allocation limit
[ 6.407679] ------------[ cut here ]------------
[ 6.407927] WARNING: CPU: 1 PID: 1592 at kernel/dma/mapping.c:503 dma_alloc_attrs+0x36/0x60
...
[ 6.413161] # ttm_pool_alloc_basic: ASSERTION FAILED at drivers/gpu/drm/ttm/tests/ttm_pool_test.c:162
[ 6.413161] Expected err == 0, but
[ 6.413161] err == -12 (0xfffffffffffffff4)
[ 6.416872] not ok 4 One page, with coherent DMA mappings enabled
[ 6.420623] ------------[ cut here ]------------
[ 6.420900] list_add corruption. prev->next should be next (ffffffff86d3e930), but was 6b6b6b6b6b6b6b6b. (prev=ffff8f3143621e20).
and downhill from there. Granted, this is due to bad cleanup in the
ttm unit tests after a failure, but the offending code causing that failure
is already in the mainline kernel.
> Let's set up a default DMA mask that should work on any platform to fix
> it.
>
> Fixes: d03c720e03bd ("kunit: Add APIs for managing devices")
> Signed-off-by: Maxime Ripard <mripard@xxxxxxxxxx>
Tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Guenter
