Re: [PATCH] usb: core: hub power off when over-current detected

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On Thu, 8 Nov 2012, Sergei Shtylyov wrote:

> >> USB specs says that if an over-current is detected then a hub must switch off
> >> all affected port, wait to cool down and then switch on.
> 
> >> There are few controllers, which does not follow it, and expects software
> >> to switch off the port power.
> 
> > Can you give any examples?
> 
>    The example that springs to my mind is EHCI -- but the EHCI driver takes care
> for switching the port off.

Which EHCI implementation are you talking about?  And where does the 
EHCI driver switch ports off when they encounter an overcurrent 
condition?

The EHCI controllers I have used do not allow software to control the 
port power levels at all.  It's all done in hardware.

Alan Stern

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