Messages in this thread | | | Subject | Re: [PATCH v1 2/2] drivers/gpu/drm: don't select DMA_CMA or CMA from aspeed or etnaviv | From | David Hildenbrand <> | Date | Thu, 8 Apr 2021 14:00:48 +0200 |
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On 08.04.21 13:44, Arnd Bergmann wrote: > On Thu, Apr 8, 2021 at 1:00 PM David Hildenbrand <david@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?
"Random drivers should not override a user configuration of core knobs (e.g., CONFIG_DMA_CMA=n)."
Let's assume I'm a distribution and want to set CONFIG_CMA=n or want to set CONFIG_DMA_CMA=n with CONFIG_CMA=y; there is no way to do that with e.g., DRMA_ASPEED_GFX=y because it will always override my (user!) setting -- even though it doesn't really always need it. Using "select" is the problem here.
> > 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 >
That's precisely what I had first, with an additional "WANT_CMA" -- but looking at the number of such existing options (I was able to spot 1 !) I wondered if there is a better approach to achieve the same; "imply" sounded like a good candidate.
-- Thanks,
David / dhildenb
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