On 2012年06月01日 23:55, Alan Stern wrote:
On Fri, 1 Jun 2012, Lan Tianyu wrote:
Change since v1: move sysfs files from usb hub device sysfs directory to usb
hub interface sysfs directory.
This patch is to add two sys files for each usb hub ports to control port's power.
Control port's power through setting or clearing PORT_POWER feature.
The new sys files is under the usb hub interface sysfs portx directory.
ls /sys/bus/usb/devices/1-0:1.0
bAlternateSetting bInterfaceClass bInterfaceNumber bInterfaceProtocol
bInterfaceSubClass bNumEndpoints driver ep_81 modalias power
subsystem supports_autosuspend uevent port1 port2 port3 port4
ls /sys/bus/usb/devices/1-0:1.0/port1
control state
You need to add entries to Documentation/ABI explaining these new
files.
Ok. I will add.
control has three options. "auto", "on" and "off"
"auto" - if port without device, power off the port.
(This patch only cover ports without device)
Is this option really needed? Can't userspace check first to see
whether there is a device, and then write "off" if there isn't?
Yes, user-space can dealt with. So "auto" only work for ports with
devices.
Alan Stern
--
Best Regards
Tianyu Lan
linux kernel enabling team
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