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

[Kamil Konieczny]

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?

> 
> 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