[sane-devel] On CONFIG_USB_SUSPEND and black scans

Gerhard Jaeger gerhard at gjaeger.de
Mon May 7 09:49:12 UTC 2007


one thing to add. I've tested the Plustek-Backend on a 
recent Debian system x86_64 AND CONFIG_USB_SUSPEND activated.
Result: no problems so far.


On Dienstag, 1. Mai 2007, Julien BLACHE wrote:
> JKD <jkdsoft at gmail.com> wrote:
> Hi,
> >> Connections remain ? Is the connection still open when the device goes
> >> to sleep, or is it closed before that ?
> >> 
> >> Could we be failing to catch an error here ?
> >
> > As I understand, connection starts with sanei_usb_open in sane_open()
> > and remains until sanei_usb_close in sane_close() function. I don't know
> > if returning zeroes in bulk transfers means that device is suspended (I've
> That would be a silly thing to do, returning bogus data instead of
> returning an error...
> > no way to know device status) but connection remains because control
> > transfers still work.
> >
> > Should kernel suspend a device when it's openned/accessed by a proccess?
> Obviously this shouldn't be the case.
> > The fact is that (in my case) libsane-extras's backend returns a black
> > image and once compiled by me, it works fine getting always the right
> > image. And I'm sure that I've not changed anything in the way backend
> > communicates to device. It's the same code provided by SANE API.
> There's no sane reason for that that I can think of, *grmbl*
> JB.

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