[sane-devel] Some weirdness with a Canon LiDE 220

[Stef]

On 17/12/2015 04:41, Scott Alfter wrote:
> On 2015-12-16 19:18, m. allan noah wrote:
>> You found the patch. If removing that fixes the issue, then our
>> workaround is causing problems with current linux kernels. I suppose
>> we will have to make the workaround controlled by an environment
>> variable in that case.
>
> It didn't fix it when using gentoo-sources (kernel) 4.1.12, but in 
> combination with gentoo-sources 4.3.3, I have only had one failure to 
> scan, and that was when I told it to try scanning at 4800 dpi. At 
> normal settings (600 dpi and below), I suspect it'll scan all day.  It 
> even completed a scan at 2400 dpi after a bit of a delay.
>
> I then put the patch back in (or, more precisely, didn't patch it 
> out), recompiled, and tried again under the newer kernel.  It seems to 
> be running about the same with the workaround as without: an "invalid 
> argument" error at 4800 dpi, but it works at 2400 dpi and below.
>
> The patch doesn't appear to be making much of a difference one way or 
> the other.  Instead, it would appear the kernel developers may have 
> fixed whatever was broken with USB 3.0 support somewhere between 
> 4.1.12 and 4.3.3.
>
     Hello,

     before scanning, the scanner calibrates itself. The higher the 
resolution, the longer the calibration takes. The calibration data is 
then cached , and subsequent scans are faster. That explains the delay 
you saw at 2400 dpi.
     For the 4800 dpi scan, what is the scan area used (width, height) ?

Regards,
     Stef