On 2013/3/30 4:24, Alan Stern wrote:
On Fri, 29 Mar 2013, Sarah Sharp wrote:
Also, bear in mind that the proposed patch does not give userspace a
way to power off ports via usbfs. What the new code does is a
power-off reset -- it turns off power to the port, waits a short time,
and then turns power back on.
I think we need two separate IOCTLs: turn off the port power and turn it
on. Then we get the manual port power off for our QA testing, distros
can make interesting policies about manually powering off ports, and
userspace can choose how long they want the port to be off. After all,
different devices may need a longer powered-off period than others.
Or one port-power IOCTL that takes the setting as an argument. Yes,
this would be more flexible than a power-off reset.
Hi Alan & Sarah:
I just recall why I put power off and power on in one ioctl.
At first, I also tried to make power on and power off into two ioctls.
But I found after powering off a device, the usbfs device node will
be removed and so can't power on the port via the same usbfs node.
For this point, we should add usbfs node for usb port?
Alan Stern
--
Best Regards
Tianyu Lan
linux kernel enabling team
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