[PATCH] usb: dwc2: host: Fix ahbcfg for rk3066
heiko at sntech.de
Sat Oct 24 06:08:05 PDT 2015
Am Dienstag, 20. Oktober 2015, 16:33:53 schrieb Douglas Anderson:
> The comment for ahbcfg for rk3066 parameters (also used for rk3288)
> claimed that ahbcfg was INCR16, but it wasn't. Since the bits weren't
> shifted properly, the 0x7 ended up being masked and we ended up
> programming 0x3 for the HBstLen. Let's set it to INCR16 properly.
> As per Wu Liang Feng at Rockchip this may increase transmission
> efficiency. I did blackbox tests with writing 0s to a USB-based SD
> reader (forcefully capping CPU Freq to try to measure efficiency):
> cd /sys/devices/system/cpu/cpu0/cpufreq
> echo userspace > scaling_governor
> echo 126000 > scaling_setspeed
> for i in $(seq 10); do
> dd if=/dev/zero of=/dev/sdb bs=1M count=750
> With the above tests I found that speeds went from ~15MB/s to ~18MB/s.
> Note that most other tests I did (including reading from the same USB
> reader) didn't show any difference in performance.
> Signed-off-by: Douglas Anderson <dianders at chromium.org>
I gave this a spin on a rk3288-firefly, runs fine and doesn't have any
negative effects, so
Tested-by: Heiko Stuebner <heiko at sntech.de>
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