[PATCH i-g-t v3 02/41] lib/vkms: Add minimal VKMS library and test device default files

[Karthik B S]

On 8/5/2025 9:59 PM, Kamil Konieczny wrote:
> Hi José,
> On 2025-08-05 at 11:20:09 +0200, José Expósito wrote:
>> Hi Louis,
>>
>> On Wed, Jul 16, 2025 at 11:22:38AM +0200, Louis Chauvet wrote:
>>>
>>> Le 15/07/2025 à 12:24, José Expósito a écrit :
>>>> Create a library containing helpers for creating VKMS devices and
>>>> configuring them dynamically using configfs.
>>>> For the moment, add the minimal number of helpers to be able to start
>>>> testing VKMS's configfs support: Create device, destroy device and
>>>> destroy all devices.
>>>>
>>>> Also, include the simplest possible test using those helpers (checking
>>>> the device's default files) and the scaffolding required to generate
>>>> the documentation.
>>>>
>>>> Co-developed-by: Jim Shargo <jshargo at chromium.org>
>>>> Signed-off-by: Jim Shargo <jshargo at chromium.org>
>>>> Co-developed-by: Marius Vlad <marius.vlad at collabora.com>
>>>> Signed-off-by: Marius Vlad <marius.vlad at collabora.com>
>>>> Signed-off-by: José Expósito <jose.exposito89 at gmail.com>
>>>> ---
>>>>    docs/testplan/meson.build        |   7 +-
>>>>    lib/igt_vkms.c                   | 207 +++++++++++++++++++++++++++++++
>>>>    lib/igt_vkms.h                   |  27 ++++
>>>>    lib/meson.build                  |   1 +
>>>>    meson.build                      |   8 ++
>>>>    tests/meson.build                |   2 +
>>>>    tests/vkms/meson.build           |  13 ++
>>>>    tests/vkms/vkms_configfs.c       | 132 ++++++++++++++++++++
>>>>    tests/vkms/vkms_test_config.json |  72 +++++++++++
>>>>    9 files changed, 467 insertions(+), 2 deletions(-)
>>>>    create mode 100644 lib/igt_vkms.c
>>>>    create mode 100644 lib/igt_vkms.h
>>>>    create mode 100644 tests/vkms/meson.build
>>>>    create mode 100644 tests/vkms/vkms_configfs.c
>>>>    create mode 100644 tests/vkms/vkms_test_config.json
>>>>
>>>> [...]
>>>> diff --git a/lib/igt_vkms.c b/lib/igt_vkms.c
>>>> new file mode 100644
>>>> index 000000000..fa41f741e
>>>> --- /dev/null
>>>> +++ b/lib/igt_vkms.c
>>>> [...]
>>>> +static int detach_pipeline_items(const char *path, const struct stat *info,
>>>> +				 const int typeflag, struct FTW *pathinfo)
>>> As there will be a new "color pipeline" in DRM, can you rename this set of
>>> functions to avoid confusion? I don't have preference for the name, what do
>>> you think about "dc" for display controller?
> Could you give a link to lore.kernel.org for this 'color pipeline'?
>
>>> (ditto for the rest of the series)
>>>
>>> With this modification:
>>> Reviewed-by: Louis Chauvet <louis.chauvet at bootlin.com>
>> The "pipeline" here refers to the display pipeline as in the docs:
>> https://docs.kernel.org/gpu/drm-kms.html#overview
>>
>> Given that the VKMS driver is a display driver and that "enum vkms_pipeline_item"
>> contains those entites, I find easy to understand what we are talking about.
>>
>> What do you think about leaving the display pipeline as "pipeline" and, once we
>> add the color pipeline, use "color_pipeline"?
> These looks resonable. Karthik, could you comment on this?

Yes, this looks good.

Thanks,
Karthik.B.S
>
>> I can rename all instances of "pipeline" to "display_pipeline" (with a lot of work,
>> 100 occurences in igt_vkms.c in 41 patches), but I find it too verbose for little
>> clarification.
> Well, you can use sed script for this but I am afraid that there
> are many other places in igt with 'pipeline' meaning
> 'display pipeline', so it would be a lot more work to do.
>
> Regards,
> Kamil
>
>> Jose
>>
>>>> [...]
>>> -- 
>>> Louis Chauvet, Bootlin
>>> Embedded Linux and Kernel engineering
>>> https://bootlin.com