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

Eric Anholt eric at anholt.net
Mon Mar 6 11:12:23 PST 2017

Stefan Wahren <stefan.wahren at i2se.com> writes:

>> 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?

Bonus points for either no extraneous changes or doing savedefconfig
first, but I wouldn't reject patches over it.
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