Re: bisected regression, v3.5 -> next-20120724: PCI PM causes USB hotplug failure

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On Thu, 26 Jul 2012, Bjørn Mork wrote:

> Huang Ying <ying.huang@xxxxxxxxx> writes:
> 
> > Do you have time to try the below patch?
> 
> Sure.  Looks OK wrt the USB problems, but may cause problems with the
> PCIe WiFi card.  Unless those are related to other changes in -next.
> 
> Anyway, for I applied your patch on top of next-20120724 for
> consistency (still without Rafael print fix, so we get the D4 below).  
> This results in different stats for the uhci_hcd and ehci_hcd:
> 
> 
> Jul 26 12:13:42 nemi kernel: [   72.820305] uhci_hcd 0000:00:1a.2: power state changed by ACPI to D2
> Jul 26 12:13:42 nemi kernel: [   72.835101] uhci_hcd 0000:00:1d.0: power state changed by ACPI to D2
> Jul 26 12:13:44 nemi kernel: [   74.808770] uhci_hcd 0000:00:1a.0: power state changed by ACPI to D2
> Jul 26 12:13:44 nemi kernel: [   74.840293] ehci_hcd 0000:00:1d.7: power state changed by ACPI to D4
> Jul 26 12:13:44 nemi kernel: [   74.840326] ehci_hcd 0000:00:1a.7: power state changed by ACPI to D4
> 
> I assume that is expected, based on the lspci output I posted earlier.
> Overall I get a nice mix of allowed/disallowed:

...

> USB hotplugging seems to work fine with this.

Don't be too sure.  Have you tested to see if it still works after 
doing "rmmod ehci-hcd"?

So far you have tested the EHCI controllers, but have you tested the 
UHCI controllers?  Unloading ehci-hcd will force them to be used.

Alan Stern

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