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

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

[Benjamin Poirier]

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@rowland.harvard.edu>
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.

Thanks,
-Ben

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

[Greg KH]

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@rowland.harvard.edu>
> 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@vger.kernel.org yesterday,
can you try that one out (sorry, can't dig it out at the moment...)

thanks,

greg k-h

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

[Benjamin Poirier]

On 29/11/10 10:26 PM, Greg KH wrote:
> 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@rowland.harvard.edu>
>> 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@vger.kernel.org yesterday,
> can you try that one out (sorry, can't dig it out at the moment...)

I think that's the one:
http://www.spinics.net/lists/linux-usb/msg39257.html

It indeed fixes the problem. Thanks!

btw. it seems I was late to the game, I should've checked bugzilla too,
https://bugzilla.kernel.org/show_bug.cgi?id=23012

-Ben

> 
> thanks,
> 
> greg k-h