Bump CMA to 64M by default as found in 3.15 multi_v7_defconfig

The commit d1c912c1001f was made into tegra_defconfig and later
forwared to multi_v7_deconfig as 0c86f089e66a93

Quoting original commit into the kernel tree:
- Allocate 64 MiB for CMA by default; the default 16MiB is not enough
  for the majority of use-cases. This can still be overridden by the cma
  command-line option.

If this patch is not applied, KMS drivers using CMA would
rapidly exhaust the allocated memory. This was seen on tegra_drm
(from tagr libdrm/opentegra with exa support on freedesktop.org)
...
kernel: host1x drm: failed to allocate buffer with size 2457600
...

On the other side, CMA allocated memory can easily be freed
http://lwn.net/Articles/486301/
"Freeing memory is much simpler process..."
Whereas they can only be allocated at boot time
https://lkml.org/lkml/2014/5/7/810
"CMA is introduced to provide physically contiguous pages at runtime.
For this purpose, it reserves memory at boot time."

This patch is about to have a convenant generic default
and to match upstream kernel default value.
Everything can be setup back into fedora tools such as arm-boot-config

At some point, tegra will move to IOMMU and will not rely on CMA

Tested on Toshiba AC100 (with 512M RAM with cma=128M zram=1x128M)
with opentegra DDX driver

1 files changed, 1 insertions, 1 deletions

diff --git a/config-arm-generic b/config-arm-generic
index 3d923896..6e7796c6 100644
--- a/config-arm-generic
+++ b/config-arm-generic
@@ -163,7 +163,7 @@ CONFIG_THERMAL_GOV_USER_SPACE=y
 CONFIG_CMA=y
 CONFIG_DMA_CMA=y
 # CONFIG_CMA_DEBUG is not set
-CONFIG_CMA_SIZE_MBYTES=16
+CONFIG_CMA_SIZE_MBYTES=64
 CONFIG_CMA_SIZE_SEL_MBYTES=y
 # CONFIG_CMA_SIZE_SEL_PERCENTAGE is not set
 # CONFIG_CMA_SIZE_SEL_MIN is not set