On Thu, 18 May 2006, Guennadi Liakhovetski wrote:
> On Thu, 18 May 2006, Guennadi Liakhovetski wrote:
>
> > doesn't. You only get some control URBs which I haven't tried yet to
> > interpret exactly, and first on power on you get an URB on the interrupt
>
> Ok, I decoded them: 2 control URBs on power off and on are just the
> URBs sent by the program to switch the port power:-) So, there's really
> nothing else happening there after power-off - no status report...
>
> Looks like USB-2.0 (11.11, 11.12.{3,4}) doesn't require a hub to send port
> status change on port power off? So, it's legitimate? And we have no
> chance to trace this in the kernel?
The relevant part of the spec is 11.24.2.7.2.1, which says that the
C_PORT_CONNECTION bit is set by attach or detach detect events, implying
it is not set by power changes.
It would be good to notify the kernel that it should check for
disconnected ports when you shut off the power. Right now there's no way
to do it. However it wouldn't be hard to add a sysfs interface for such a
purpose.
Alan Stern
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