[RFC PATCH 1/1] drm/format-helper: Add KUnit tests for drm_fb_xrgb8888_to_rgb332()

[Daniel Latypov]

On Tue, May 31, 2022 at 11:45 AM José Expósito
<jose.exposito89 at gmail.com> wrote:
> >
> > From above, a)
> > Specifically here, it'd be encouraged to instead do
> >   depends on DRM && KUNIT=y && DRM_KMS_HELPER
>
> My first attempt was to go with:
>
>         depends on KUNIT=y && DRM && DRM_KMS_HELPER
>
> However, when I try to run the tests I get this error:
>
>         $ ./tools/testing/kunit/kunit.py run --kunitconfig=drivers/gpu/drm --arch=x86_64
>         Regenerating .config ...
>         Populating config with:
>         $ make ARCH=x86_64 olddefconfig O=.kunit
>         ERROR:root:Not all Kconfig options selected in kunitconfig were in the generated .config.
>         This is probably due to unsatisfied dependencies.
>         Missing: CONFIG_DRM_KMS_HELPER=y, CONFIG_DRM_FORMAR_HELPER_TEST=y
>
> I wasn't able to figure out why that was happening, so I decided to use
> "select", which seems to solve the problem.
>
> Do you know why this could be happening?

Ah, you should probably ignore my suggestion then.

Looking at the Kconfig file, it's defined as
  config DRM_KMS_HELPER
  tristate
  depends on DRM
  help
    CRTC helpers for KMS drivers.

Notably, the config lacks a description string.
IIUC, this makes it a "hidden" kconfig option, i.e. you can't directly
select it yourself in a .config, it must be selected by another
kconfig option.

E.g. you can try selecting it manually and see it fail via:
$ ./tools/testing/kunit/kunit.py config --arch=x86_64
--kconfig_add=CONFIG_DRM=y --kconfig_add=CONFIG_DRM_KMS_HELPER=y
...
Missing: CONFIG_DRM_KMS_HELPER=y

So having the test select it makes the most sense, unless there's a
better kconfig option to automatically select it (I have no idea,
someone with knowledge of the DRM code might though).

Daniel