Subject: Re: kern/37459: USB device issues on suspend/resume
To: None <>
From: Matthias Drochner <>
List: netbsd-bugs
Date: 12/07/2007 23:13:18 said:
> 		* don't remove device: device stays attached
> 		* remove device: device detaches on resume
> 		* add new device: device attaches on resume 

The code in uhub.c:uhub_explore() is called on many occasions, it should
be able to catch these cases. As long as there are no bogus hub status
bits in the process... If there a problems one should first find out
what the parent device is (uhci/ohci/ehci/uhub) and check whether it
behaves strange on suspend/resume.

>		* remove and re-add device: device detaches and re-attaches
>		  on resume

That's complicated, considering the different cases if the same device,
a similar one or a completely different are attached. The USB hub
likely doesn't notice by itself, unless the speed changes on an ehci.
(need to check the specs though)
The right solution would probably be to read some VPD or so after each resume,
but this is beyond the scope of your power management work... it
touches jachym's SOC project, I'd wait at least until this has settled.

best regards

Forschungszentrum Juelich GmbH
52425 Juelich

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