[sane-devel] [SOLVED] Re: Unstable scanning with Fujitsu fi-7160

[Paul Graff]

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 <
>>>> sane-devel at alioth-lists.debian.net> 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"
>>>>
>
>