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 12:36:59 +0200 |
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On 08.04.21 12:27, David Hildenbrand wrote: > On 08.04.21 12:20, Arnd Bergmann wrote: >> On Thu, Apr 8, 2021 at 11:22 AM David Hildenbrand <david@redhat.com> wrote: >>> >>> Random drivers should not override a user configuration of core knobs >>> (e.g., CONFIG_DMA_CMA=n). Use "imply" instead, to still respect >>> dependencies and manual overrides. >>> >>> "This is similar to "select" as it enforces a lower limit on another >>> symbol except that the "implied" symbol's value may still be set to n >>> from a direct dependency or with a visible prompt." >>> >>> Implying DRM_CMA should be sufficient, as that depends on CMA. >>> >>> Note: If this is a real dependency, we should use "depends on DMA_CMA" >>> instead - but I assume the driver can work without CMA just fine -- >>> esp. when we wouldn't have HAVE_DMA_CONTIGUOUS right now. >> >> 'imply' is almost never the right solution, and it tends to cause more >> problems than it solves. > > I thought that was the case with "select" :) > >> >> In particular, it does not prevent a configuration with 'DRM_CMA=m' > > I assume you meant "DRM_CMA=n" ? DRM_CMA cannot be built as a module. > >> and 'DRMA_ASPEED_GFX=y', or any build failures from such >> a configuration. > > I don't follow. "DRM_CMA=n" and 'DRMA_ASPEED_GFX=y' is supposed to work > just fine (e.g., without HAVE_DMA_CONTIGUOUS) or what am I missing? > >> >> If you want this kind of soft dependency, you need >> 'depends on DRM_CMA || !DRM_CMA'. > > Seriously? I think the point of imply is "please enable if possible and > not prevented by someone else". Your example looks more like a NOP - no? > Or will it have the same effect?
I just tried (remove CONFIG_DMA_CMA from .config followed by make) and the default will be set to "N" (when querying the user). So it indeed looks like a NOP - unless I am missing something.
-- Thanks,
David / dhildenb
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