[PATCH v1 2/2] drivers/gpu/drm: don't select DMA_CMA or CMA from aspeed or etnaviv

[Arnd Bergmann]

On Thu, Apr 8, 2021 at 1:00 PM David Hildenbrand <david at redhat.com> wrote:
> >
> > It is a somewhat awkward way to say "prevent this symbol from
> > being =y if the dependency is =m".
>
> What would be the right thing to do in the case here then to achieve the
> "if DRMA_ASPEED_GFX is enabled, also enable DMA_CMA id possible"?
>
> One approach could be to have for DMA_CMA
>
> default y if DRMA_ASPEED_GFX
>
> but it feels like the wrong way to tackle this.

I'm still not sure what you are trying to achieve. Is the idea only to provide
a useful default for DMA_CMA depending on which drivers are enabled?

This is something you could do using a hidden helper symbol like

config DRMA_ASPEED_GFX
       bool "Aspeed display driver"
       select DRM_WANT_CMA

config DRM_WANT_CMA
       bool
       help
          Select this from any driver that benefits from CMA being enabled

config DMA_CMA
       bool "Use CMA helpers for DRM"
       default DRM_WANT_CMA

         Arnd