Thanks for your feedback, Uwe! On Thu, Jan 14, 2016 at 4:19 AM, Uwe Kleine-König <uwe+deb...@kleine-koenig.org> wrote: > Hello Roger, > > On 01/13/2016 02:11 PM, Roger Shimizu wrote: >> Package: src:linux >> Version: 3.16.7-ckt20-1+deb8u1 >> Severity: normal >> Control: notfound -1 3.16.7-ckt4-3 >> Control: found -1 3.16.7-ckt7-1 >> Control: found -1 3.16.7-ckt20-1+deb8u1 >> Control: notfound -1 4.2.6-3~bpo8+2 >> Control: notfound -1 4.3.3-5~bpo8+1 >> Control: notfound -1 4.4~rc8-1~exp1 >> >> I need to run the following command to enable USB port on Linkstation >> LS-WXL/WSXL (armel/kirkwood with DTS [0] ): >> echo 37 >/sys/class/gpio/export >> echo out > /sys/class/gpio/gpio37/direction >> echo 1 > /sys/class/gpio/gpio37/value > > Side note: you can shorten that to: > > echo 37 > /sys/class/gpio/export > echo high > /sys/class/gpio/gpio37/direction
Learned new tips. Thank you! >> The 3-line script runs well on Jessie rootfs + kernel listed below: >> - 3.16.7-ckt4-3 >> - 4.2.6-3~bpo8+2 >> - 4.4~rc8-1~exp1 >> But fails from 3.16.7-ckt7-1 to 3.16.7-ckt20-1+deb8u1 (latest jessie kernel). >> >> The error message is like this: >> # echo 37 >/sys/class/gpio/export >> -bash: echo: write error: Device or resource busy > > Looking at the device tree I'd say it's correct that the gpio cannot be > controlled from user space because it's used to enable usb. I don't understand why it's not able to control the gpio. Could you please explain in detail? I'm the upstream contributor for this DTS. I know there may be something wrong with the gpio part, but I don't know how to know which part is not working. > A quick look at the provided dmesg for 3.16.7-ckt7-1 makes me expect > that usb works there without the gpio commands above? If so there is no > bug, right? Yes, dmesg shows USB is recognized. But actually it's not working until user land's gpio export and setting. If gpio export fails, the USB won't work at all. I guess the gpio pin is to set whether to give USB power. Cheers, Roger
