[PATCH RFC 6/7] ARM: bcm2835_defconfig: Increase CMA for VC4

Eric Anholt eric at anholt.net
Tue Jun 27 15:08:31 PDT 2017

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

> The VC4 needs more memory than the default setting:
>     cma: cma_alloc: alloc failed, req-size: 4096 pages, ret: -12
>     vc4-drm soc:gpu: failed to allocate buffer with size 16777216
> So increase the value to 32 MB and fix this issue.

Reviewed-by: Eric Anholt <eric at anholt.net>

The VC4 CMA value will help get a 1920x1080 screen brought up by
default, which is clearly needed.

It wouldn't let you get any 3D working at that resolution -- you have
16MB of binner, 8MB of fbcon, then at least 16MB for your
double-buffered application's framebuffers, without even any other GL
storage counted (1MB of stream uploader, whatever textures you've got).
I would also r-b a patch that set the CMA to 64 or 128MB.  But then,
this defconfig is only really for kernel build testing, and not used by
any distributions that I know of.
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