• Douglas Anderson's avatar
    usb: dwc2: host: Fix ahbcfg for rk3066 · f1659303
    Douglas Anderson authored
    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.
    Tested-by: default avatarHeiko Stuebner <heiko@sntech.de>
    Acked-by: default avatarJohn Youn <johnyoun@synopsys.com>
    Reviewed-by: default avatarLiangfeng Wu <wulf@rock-chips.com>
    Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
    Signed-off-by: default avatarFelipe Balbi <balbi@ti.com>
platform.c 13 KB