Good job on this.
On 1/24/26 10:50 AM, Simon Matter via sane-devel wrote:
Hi,
Would it be possible for someone to look at the button daemon and see if
there are obvious errors that you lead to issues as discussed here.
The code is attached again to this mail.
Finally I found out how this can be solved. The following patch does the
trick:
@@ -59,7 +59,11 @@ int
main (int argc, char **argv)
{
int i, idx;
- struct timespec ts = { .tv_sec = 0, .tv_nsec = 100000000L };
+ /* Important query rate limiting, the old value of 0.1s was too
+ * small. USB scanners can block on newer Linux systems if the
+ * query rate is too high.
+ */
+ struct timespec ts = { .tv_sec = 0, .tv_nsec = 500000000L };
time_t last_reopen;
SANE_Bool new, print_err;
const SANE_Option_Descriptor *opt[MAX_BUTTONS];
Thank God this is solved now before I gave up on it! Still, I believe this
is a bug in recent Linux systems and shouldn't happen. But I tested from
MX Linux to latest Fedora so many systems and it's always there.
Regards,
Simon
Thanks,
Simon
I start to believe the problem is not in SANE itself but in the button
daemon we are using (see attachement).
Our software is running the button daemon and waits for events, then
terminates the button daemon and does the appropriate scanimage job, and
then starts the button daemon again.
The button daemon is a modified version of some daemon which was
floating
around many years ago. It has worked well for the last 15 years or so.
Maybe there is some modification needed to make it work well with newer
SANE.
If someone who knows SANE better than me would take a look at it, that
would be much appreciated.
Thanks,
Simon
We need to isolate the problem if possible- I expect if you compile an
older, known working sane-backends on your current computer, the
problem
will persist. That would indicate hardware or OS level issue.
allan
On Wed, Jan 14, 2026 at 9:35 AM Simon Matter via sane-devel <
[email protected]> wrote:
Hello,
On 2026-01-14 14:59, Simon Matter via sane-devel wrote:
These scanners work perfectly fine with very old sane-backends
and operating system.
Does it work on the exact same computer
where it fails or does it work on old computers?
It works fine on old computers with old software.
I ask because of possible USB 3 related issues, see
https://en.opensuse.org/SDB:Configuring_Scanners#USB
Thanks, I'll check it out.
Simon
--
"well, I stand up next to a mountain- and I chop it down with the edge
of
my hand"
