[RFC 1/1] drm: allow to use mmuless SoC

[Benjamin Gaignard]

2016-11-30 16:19 GMT+01:00 Laurent Pinchart <laurent.pinchart at ideasonboard.com>:
> Hi Benjamin,
>
> On Wednesday 30 Nov 2016 16:08:23 Benjamin Gaignard wrote:
>> 2016-11-30 14:52 GMT+01:00 Daniel Vetter <daniel at ffwll.ch>:
>> > On Wed, Nov 30, 2016 at 12:21:24PM +0100, Benjamin Gaignard wrote:
>> >> Some platforms without MMU have display drivers where a drm/kms driver
>> >> could be implemented.
>> >> Before doing such kind of thing drm/kms must allow to use mmuless
>> >> devices.
>> >> This patch proposes to remove MMU configuration flag and add some
>> >> cma helpers functions to help implementing mmuless display driver
>> >>
>> >> Signed-off-by: Benjamin Gaignard <benjamin.gaignard at linaro.org>
>> >> ---
>> >>
>> >>  drivers/gpu/drm/Kconfig              |  4 +--
>> >>  drivers/gpu/drm/drm_fb_cma_helper.c  | 20 ++++++++++++
>> >>  drivers/gpu/drm/drm_gem_cma_helper.c | 62 +++++++++++++++++++++++++++++
>
> [snip]
>
>> > drm_vm.c is a legacy horror show. Instead of hacking even more garbage
>> > into this, can't we just not compile this for MMU-less platforms? A bunch
>> > of stubs in drm_internal.h is all that should be needed for this, since on
>> > MMU-less you should never be able to enable one of the legacy drivers
>> > which need the exported symbols from this file.
>>
>> Following your advice I have removed drm_vm.c from the build if
>> CONFIG_MMU is not set
>
> How about only including it if !DRM_LEGACY && !DRM_NOUVEAU ?

I don't understand the link between !DRM_LEGACY && !DRM_NOUVEAU and MMU...

By chance would you mean including only if DRM_LEGACY && DRM_NOUVEAU ?

>
>> I only had to stub drm_legacy_vma_flush() to compile.
>> I will include that in v3
>
> --
> Regards,
>
> Laurent Pinchart
>



-- 
Benjamin Gaignard

Graphic Study Group

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