[sane-devel] USB 3.0 not supported?

Stef stef.dev at free.fr
Mon May 27 20:09:28 UTC 2013

On 27/05/2013 15:49, Tom Pace wrote:
> On 05/27/2013 04:59 AM, Mike Cloaked wrote:
>> On Mon, May 27, 2013 at 12:10 AM, Tom Pace <tompace101 at gmail.com 
>> <mailto:tompace101 at gmail.com>> wrote:
>>     I couldn't find any information about USB 3 and SANE, but on my
>>     particular hardware it doesn't seem to be supported. My Epson
>>     Perfection
>>     V33 works fine when plugged into a USB 2 port, but when plugged
>>     into a
>>     USB 3 port it rarely works. I'm using the epkowa backend, and have
>>     attached a log.
>>     For all I know it could be the scanner itself doesn't support USB 3.
>>     Even though USB 3 is supposed to be backwards compatible, I
>>     understand
>>     it doesn't always work as advertised.
>>     Thanks for any insight,
>> Just for clarification does the scanner work when plugged into a usb2 
>> port on the "same" machine that it doesn't work when plugged into a 
>> usb3 port?
>> I have a different scanner (MFP) which was plugged into a usb3 port 
>> and didn't work, but which worked when plugged into a different 
>> machine that only had usb2 - but I was chasing the wrong problem 
>> because it was the same non-functional state when plugged into a usb2 
>> port on the original machine - and it turned out that the problem was 
>> with udev not knowing how to have both a printer and scanner function 
>> on the MFP working at the same time.
>> However I would also like to know more about whether usb3 is fully 
>> supported (both for any scanner that does have usb3 but also for 
>> backwards compatibility with usb2 on a computer that does not support 
>> usb3.
>> -- 
>> mike c
> Yes, it is the same machine. It is a laptop running Linux Mint 13. 
> There are 2 USB3 ports that the scanner doesn't work very well on, and 
> 1 USB2 port that it works perfectly on. The specs on the scanner 
> itself do not mention USB3, so it seems that the backwards 
> compatibility is failing somewhere. It could be within SANE, or it 
> could be within the scanner itself, or I suppose it could even be some 
> other driver/hardware on the laptop. Does anyone have any ideas how I 
> could go about narrowing this down?
> Thanks,
> Tom

     I don't know if it is the problem you have, but I have recently met 
some troubles using USB scanners on recent hardware with USB3. I 
eventually cured it by disabling USB powersaving with this kernel module 
modprobe usbcore autosuspend=-1

or if usbcore is not a module with this kernel boot parameter:

     Regarding USB3/USB3 the last paragraph of 
/usr/src/linux/Documentation/usb/power-management.txt might be interesting.


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