Re: query EHCI 3ms SUSPEND

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On Mon, 10 Dec 2007, Pandita, Vikram wrote:

> 1) So, Is it that from sysfs user interface on USB host we suspend the port (EHCI.PORTSC) so that devices see no activity on the bus and get suspended? 

That is one of the ways.

> 2) Please advise if the following is the right way to do a suspend of EHCI port with device enumerated:
> echo -n 2> /sys/devices/platform/ehci.0/usb1/1-2/1-2:1.0/power/state
> and I can see that SOFs have stopped from EHCI. Fine.

You must be using an old version of the Linux kernel.  In the current
version there is no /sys/.../power/state file.  Instead you have to
write to /sys/.../power/level.

> I tried to resume the device with:
> echo -n 0> /sys/devices/platform/ehci.0/usb1/1-2/1-2:1.0/power/state

That's the right way to do it for your old version.

> and I see that device goes to Companion Controller and fails enumeration.

Try upgrading to 2.6.23.  Or try using a different device.

> What should be the correct behavior for Selective suspend/resume for the attached device? 

I think you already know what it should be.

Alan Stern

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