[igt-dev] [PATCH] tests/kms_prime: Filter out devices that can't import buffers.

[Mark Yacoub]

@Petri Latvala would it make sense that I go ahead and move this test to i915?

On Tue, Jun 15, 2021 at 10:55 AM Christian König
<christian.koenig at amd.com> wrote:
>
> Am 15.06.21 um 16:49 schrieb Mark Yacoub:
> > On Tue, Jun 15, 2021 at 9:43 AM Christian König
> > <christian.koenig at amd.com> wrote:
> >> Hi guys,
> >>
> >> first of all thanks Rodrigo for bringing this to my attention.
> >>
> >> Mark, as the DMA-buf maintainer I unfortunately have to reject this patch.
> > This test is currently running on i915, but fails on amdgpu due to the
> > check of `import_attach` (this is the commit that introduced the
> > change: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgitlab.freedesktop.org%2Fagd5f%2Flinux%2F-%2Fcommit%2F1769152ac64b0b07583f696b621624df2ca4c840&data=04%7C01%7Cchristian.koenig%40amd.com%7Cbdc7b671688747b5b28808d9300ccce7%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637593653819504079%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=Nwdst2UNrAZXViQoXowcxzJxHGz0ktuX3OIFLESoEoo%3D&reserved=0)
> > What do you recommend instead?
>
> Dropping the test from the general KMS tests. Scanning out from imported
> DMA-bufs is completely vendor specific.
>
> >> Direct scanout from imported surfaces is not something supported with
> >> DMA-buf in general at the moment.
> > Do you mean the problem is in the test itself?
>
> Yes, exactly. Testing that without checking for vendor specific support
> is utterly nonsense.
>
> I'm pretty sure that this is not even fully supported by i915. Daniel
> Vetter and I chatted about stuff like that a while ago and he mentioned
> that i915 similar to AMD GPUs have some rather strict hardware
> requirements which are currently not expressible with DMA-buf.
>
> I'm not sure about other drivers, but my guess is that none of them will
> actually support this.
>
> Regards,
> Christian.
>
> >> We do have some support for this between AMD GPUs in A+A laptops, and it
> >> might work with i915 and some of the drivers used on ARM.
> >>
> >> But all of this is completely vendor specific since there are some very
> >> low level and hardware specific limitations to take account into.
> >>
> >> Regards,
> >> Christian.
> >>
> >> Am 15.06.21 um 15:12 schrieb Rodrigo Siqueira:
> >>> Hi Alex and Christian,
> >>>
> >>> This patch is related to prime, but I'm not familiar with this part of
> >>> our driver. Could you take a look at that?
> >>>
> >>> Thanks
> >>>
> >>> On 06/14, Mark Yacoub wrote:
> >>>> Some devices such as amdgpu do not support imported buffers.
> >>>> Filter out those devices.
> >>>> Tested on Zork with chromeos-kernel-5_4.
> >>>>
> >>>> Signed-off-by: Mark Yacoub <markyacoub at chromium.org>
> >>>> ---
> >>>>    tests/kms_prime.c | 14 ++++++++++++--
> >>>>    1 file changed, 12 insertions(+), 2 deletions(-)
> >>>>
> >>>> diff --git a/tests/kms_prime.c b/tests/kms_prime.c
> >>>> index 8cb2ca2a..480c7eb4 100644
> >>>> --- a/tests/kms_prime.c
> >>>> +++ b/tests/kms_prime.c
> >>>> @@ -249,6 +249,16 @@ static void test_crc(int exporter_fd, int importer_fd)
> >>>>       igt_display_fini(&display);
> >>>>    }
> >>>>
> >>>> +/* The test attempts to import the buffer object from one device to another.
> >>>> + * Filter out devices that aren't capable of doing this.
> >>>> + */
> >>>> +bool does_device_support_dmabuf_import(int fd) {
> >>>> +    /* AMDGPU uses VRAM. Any use of the fb will migrate it to VRAM, which is not sensible for
> >>>> +     * an imported dma-buf.
> >>>> +     */
> >>>> +    return !is_amdgpu_device(fd);
> >>>> +}
> >>>> +
> >>>>    igt_main
> >>>>    {
> >>>>       igt_fixture
> >>>> @@ -262,10 +272,10 @@ igt_main
> >>>>
> >>>>               /* ANY = anything that is not VGEM */
> >>>>               first_fd = __drm_open_driver_another(0, DRIVER_ANY | DRIVER_VGEM);
> >>>> -            igt_require(first_fd >= 0);
> >>>> +            igt_require(first_fd >= 0 && does_device_support_dmabuf_import(first_fd));
> >>>>
> >>>>               second_fd = __drm_open_driver_another(1, DRIVER_ANY | DRIVER_VGEM);
> >>>> -            igt_require(second_fd >= 0);
> >>>> +            igt_require(second_fd >= 0 && does_device_support_dmabuf_import(second_fd));
> >>>>
> >>>>               if (has_prime_export(first_fd) &&
> >>>>                   has_prime_import(second_fd))
> >>>> --
> >>>> 2.32.0.272.g935e593368-goog
> >>>>
>