[sane-devel] buttons-daemon for SANE genesys scanner

[m. allan noah]

On Sat, Jan 10, 2009 at 1:11 PM, Pierre Willenbrock
<pierre at pirsoft.dnsalias.org> wrote:
> m. allan noah schrieb:
>> On Fri, Jan 9, 2009 at 5:02 PM, Pierre Willenbrock
>> <pierre at pirsoft.dnsalias.org> wrote:
> [...]
>>
>>> Another question: Is it okay to only look at the hardware state if the
>>> frontend asks for the state of the option? That way shorter presses can
>>> be lost, if the frontend does not poll often enough.
>>
>> In my case, the scanners are smart enough to buffer the button presses
>> for 3 seconds, and I effectively read the status of all the buttons
>> from the scanner every time you ask for the value of the first option.
>> So, as long as the front-end reads within that 3 second window, no
>> presses are lost.
>>
>> If your machines dont buffer, then you might need a thread just to
>> read the status really quickly? Do you know how frequently the windows
>> driver reads the buttons?
>
> The genesys chips don't help at detecting hardware buttons. The only
> sensor logic in the chip is for the home-sensor. The rest is GPIO.

Is it possible for a user to press and release the button and have the
driver 'lose' it if you dont read the GPIO pins during the 'pressed'
inteval?

> The windows driver polls at 2Hz, this is not much better than the
> polling frequency of sanebuttonsd(1Hz). I'll go for the non-threaded
> variant for now, while making the logic work if the polling function is
> called more often than the sane options are looked at.

1Hz from sanebuttonsd has generated some complaints about being too
slow. I think we should bump it up to 2hz, so that might help.

>
>>> Before i start to ask more similar questions: Is this documented
>>> somewhere? I looked at the html-version of the standard, but could only
>>> find the capabilities thing for buttons.
>>
>> Nothing is documented. Everything we are discussing now came about
>> from prior threads on this list, and thru several iterations of button
>> support and button daemon work i did for users of the fujitsu backend.
>> IOW, this might not work for your scanners, so we should modify it if
>> required.
>
> Thanks for your answers,

NP-

allan
-- 
"The truth is an offense, but not a sin"