Re: BUG, regression. usb-serial adapter broken by PM?

From: Greg KH
Date: Mon Nov 29 2010 - 22:27:55 EST


On Mon, Nov 29, 2010 at 08:52:14PM -0500, Benjamin Poirier wrote:
> Hello,
>
> Recently, my usb-serial converter has become unusable. Attempts to open
> the device always fail with:
> open("/dev/ttyUSB0", O_RDONLY) = -1 EAGAIN (Resource temporarily unavailable)
>
> The device is a:
> ID 0c52:2101 Sealevel Systems, Inc. Serial Converter
> and uses the ftdi_sio driver.
>
> I've bisected this problem to
> commit 1bfee5bc86fdaecc912e06080583eddab7263df2
> Author: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
> Date: Sat Sep 25 23:35:00 2010 +0200
>
> PM / Runtime: Merge synchronous and async runtime routines
>
> I have other usb-serial converters that use other drivers and that are
> unaffected. I have noticed the problem on a x86_64 machine (.config
> here: http://pastebin.ca/2006414) and can reproduce it in kvm (with usb
> passthrough, .config here: http://pastebin.ca/2006416).
>
> I'll be glad to provide more info or try patches.

A patch to resolve this was sent to linux-usb@xxxxxxxxxxxxxxx yesterday,
can you try that one out (sorry, can't dig it out at the moment...)

thanks,

greg k-h
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