On 2012/11/10 0:10, Alan Stern wrote:
On Fri, 9 Nov 2012, Lan Tianyu wrote:
Some usb devices can't be resumed correctly after power off. This
patch is to add pm qos flags request to change NO_POWER_OFF and
provide usb_device_allow_power_off() for device drivers to allow or
prohibit usb core to power off the device.
If the reason for adding this request is to prevent the device from
being powered off, then shouldn't the PM QOS flag be associated with
device rather than with the port?
Hi Alan:
Great thanks for your review and good suggestions.
For pm qos flags, If put it on the port device, there is an advantage
that it can cover port without device or unused port and this part
didn't present in my this patchset.
In fact, it seems reasonable to have such a flag for both the device
and the port.
You mean for usb device or usb interface device?
I think port and device are bound. Power off port also means to power
off device. So prevent device from power off also means to prevent port
from power off. They just like a power domain. Because power is on the
port and so I thought we just needed to have pm qos flag on the port.
This maybe a simple version. If necessary, I also could add pm qos flag
for usb or usb interface device later.
Alan Stern
--
Best Regards
Tianyu Lan
linux kernel enabling team
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