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

["Christian König" <christian.koenig@amd.com>]

The alternative would be to try to create a framebuffer, but don't take 
it as a failure when that fails with the correct return code.

Christian.

Am 15.06.21 um 17:46 schrieb 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@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@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&amp;data=04%7C01%7Cchristian.koenig%40amd.com%7Cee404ba949124914936808d93014d4ef%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637593688314449415%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=qFUa24zx9I1ku%2FuRo4eFEQ4Ky0CbGoeo4VBe1HQMtBc%3D&amp;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@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
>>>>>>

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