Re: [PATCH] drm/xlnx/zynqmp-dpsub: Fix dependencies for COMPILE_TEST

[Chen-Yu Tsai <wenst@chromium.org>]

On Fri, Apr 10, 2026 at 4:49 PM Tomi Valkeinen
<tomi.valkeinen@ideasonboard.com> wrote:
>
> Hi,
>
> On 08/04/2026 11:14, Chen-Yu Tsai wrote:
> > The zynqmp-dpsub driver does not have build time dependencies on the PHY
> > or DMA drivers. These are runtime hardware restrictions.
> >
> > Group the two dependencies with ARCH_ZYNQMP so that the driver can be
> > compile tested without them.
> >
> > Signed-off-by: Chen-Yu Tsai <wenst@chromium.org>
> > ---
> > IMO the two driver dependencies could be removed altogether, but that
> > would be up to the driver and platform maintainers.
> > ---
> >   drivers/gpu/drm/xlnx/Kconfig | 4 +---
> >   1 file changed, 1 insertion(+), 3 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/xlnx/Kconfig b/drivers/gpu/drm/xlnx/Kconfig
> > index cfabf5e2a0bb..4c6729459f40 100644
> > --- a/drivers/gpu/drm/xlnx/Kconfig
> > +++ b/drivers/gpu/drm/xlnx/Kconfig
> > @@ -1,10 +1,8 @@
> >   config DRM_ZYNQMP_DPSUB
> >       tristate "ZynqMP DisplayPort Controller Driver"
> > -     depends on ARCH_ZYNQMP || COMPILE_TEST
> > +     depends on (ARCH_ZYNQMP && PHY_XILINX_ZYNQMP && XILINX_ZYNQMP_DPDMA) || COMPILE_TEST
> >       depends on COMMON_CLK && DRM && OF
> >       depends on DMADEVICES
> > -     depends on PHY_XILINX_ZYNQMP
> > -     depends on XILINX_ZYNQMP_DPDMA
> >       select DMA_ENGINE
> >       select DRM_CLIENT_SELECTION
> >       select DRM_DISPLAY_DP_HELPER
>
> I think the above looks more difficult to understand than the current
> version. We should perhaps rather drop the dependencies. But if we go
> that way, then... we can also drop DMADEVICES, DMA_ENGINE, GENERIC_PHY
> at least.

Perhaps. All the APIs for these are properly stubbed, so I guess
they also count as runtime dependencies.

> What problem does this solve? Why are these two dependencies bad for
> compile testing, but the other dependencies/selects are ok?

I was build testing changes across multiple DRM drivers in addition to
the main platform I work on. Having to find and select each dependency
was annoying.

I would say DMADEVICES and GENERIC_PHY are much more common to embedded
devices than SoC specific drivers.

> I personally don't mind hard runtime dependencies expressed in the
> Kconfig, as searching for the correct dependency-drivers when your
> driver doesn't probe is always a PITA.

I don't mind it either. But the way they are described means that compile
testing is overly dependent on having some other platform specific
driver enabled.


I suppose another way to write this would be:

    depends on ARCH_ZYNQMP if !COMPILE_TEST
    depends on PHY_XILINX_ZYNQMP if !COMPILE_TEST
    depends on XILINX_ZYNQMP_DPDMA if !COMPILE_TEST
    ...

Does that work for you?


Thanks
ChenYu