Official sunxi OpenEmbedded layer for Allwinner-based boards.
This layer depends on the additional layer:
meta-openembedded: git://git.openembedded.org/meta-openembedded
Tested with core-image-base.
Maintainers:
- Nicolas Aguirre aguirre.nicolas@gmail.com
- Enrico Butera ebutera@users.sourceforge.net
- Sergey Lapin slapin@ossfans.org
The default machine settings are meant to be the lowest common denominator, maximizing generality. Significantly better performance (2x-3x) can be achieved with the following settings:
Allwinner A20
For Allwinner A20 (Cubieboard2/CubieTruck), the following tuning options are recommended:
Enable hardfloat, thumb2 and neon capabilities
DEFAULTTUNE = "cortexa7hf-neon-vfpv4"
This tuning profile takes advantage of the Allwinner A20 hardfloat, neon and vfpv4 capabilities.
Change CPU governor to ondemand, and tune settings
echo ondemand > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
echo 336000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_min_freq
echo 912000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
#More aggressive
#echo 1008000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq
echo 40 > /sys/devices/system/cpu/cpufreq/ondemand/up_threshold
echo 200000 > /sys/devices/system/cpu/cpufreq/ondemand/sampling_rate
This code changes the default CPU governor from fantasy to ondemand, and tunes its settings, as recommended at http://linux-sunxi.org/Cpufreq
For additional discussion, see linux-sunxi#25