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

[Laurent Pinchart]

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 only had to stub drm_legacy_vma_flush() to compile.
> I will include that in v3

-- 
Regards,

Laurent Pinchart