[PATCH RFC] ARM: bcm2835: Enable missing CMA settings for VC4 driver

Stefan Wahren stefan.wahren at i2se.com
Mon Mar 6 10:19:35 PST 2017

> Eric Anholt <eric at anholt.net> hat am 6. März 2017 um 18:40 geschrieben:
> Stefan Wahren <stefan.wahren at i2se.com> writes:
> > Currently bcm2835_defconfig has CMA disabled which makes the
> > HDMI output on a Raspberry Pi 1 stop working during boot:
> >
> >     fb: switching to vc4drmfb from simple
> >     Console: switching to colour dummy device 80x30
> >     [drm] Initialized vc4 0.0.0 20140616 for soc:gpu on minor 0
> >     [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
> >     [drm] Driver supports precise vblank timestamp query.
> >     vc4-drm soc:gpu: failed to allocate buffer with size 9216000
> >     vc4-drm soc:gpu: Failed to set initial hw configuration.
> >
> > So enable CMA and DMA_CMA in bcm2835_defconfig.
> Yeah, enabling CMA in the defconfig has been the plan so far.  Other
> drivers generally don't seem to select CMA either (I see one in git
> grep).
> Reviewed-by: Eric Anholt <eric at anholt.net>
> Note for if you end up editing multi_v7_defconfig or arm64 defconfig in
> the future: arm-soc wants you to only change the lines that your patch
> needs to change, rather than having any extraneous changes from
> savedefconfig in there.  I'm fine this for bcm2835_defconfig, though.

I needed a draft for a discussion because i wasn't sure about the proper fix. In the past Stephen wanted such changes to be split up in a clean up patch and the functional patch.

Do you prefer Stephen's or the arm-soc variant?

Btw multi_v7_defconfig and arm64 defconfig are fine.

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