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

Eric Anholt eric at anholt.net
Mon Mar 6 09:40:39 PST 2017

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

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.
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