On 2012/7/18 12:43, Oliver Neukum wrote:
On Tuesday 17 July 2012 14:52:51 Sarah Sharp wrote:
2. If an internal USB port is suspended with remote wakeup disabled,
power off the port. Add code to the USB core to ignore the device
disconnect in this special case, so the driver thinks the device is
still suspended. Issue a reset-resume when the driver wants to resume
the device.
That policy would be safe, because for 1) we would never see a USB
device connection, and thus wouldn't miss the connection when we powered
off the port. 2) is safe because we won't miss a remote wakeup while
the port is powered off, and the device can't be disconnected by the
user because it's an internal USB device.
That is still problematic. Because it depends on the driver and the core
being able to reinit a device from a cold start. For devices that take
a firmware this is untrue. Unfortunately internal BT and 3G devices are
the most prominent examples of devices needing firmware.
hi oliver:
we can add a new variable for driver to indicate whether it can
support usb port power off mechanism to deal with this issue.
I have a question that reset-resume still can not resolve firmware
problem? I think this depend on driver. right?
Regards
Oliver
--
Best Regards
Tianyu Lan
linux kernel enabling team
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