[sane-devel] CanoScan LiDE 220... on a Raspberry Pi.

[Johannes Meixner]

Hello

On May 18 19:37 Kelly Price wrote (excerpt):
> * First connected to a Pi 3B+: failed with same error as USB 3.0 over xhci.
> * Connected to a Chromebook with USB 2.0 ports over ehci: works 100% with xsane
> * Connected to a Pi 2B: works 100% with scanimage
> * Connected back to the Pi 3B+:  now works 100% with scanimage
>
> Maybe some initiation has to happen over ehci for it all to work
> properly.  Weird.

Interesting finding!

I guess your USB scanner has its own power supply
(some USB scanners get power via USB only)
and you kept it connected to its power supply
while you exchanged its USB connection to the
above listed computers?

In this case I also think some specific initiation
inside the scanner has to happen to make it work.

Or did you also disconnect your USB scanner from its
power supply so that it was completely switched off
each time when you exchanged its USB connection?

I am neither a USB expert nor do I use a Raspberry Pi
but I am interested what the root cause could be
why sometimes some scanners don't work with xhci_hcd,
cf.
https://en.opensuse.org/SDB:Configuring_Scanners#USB
and
https://alioth-lists.debian.net/pipermail/sane-devel/2019-January/036525.html
and more like that...


Kind Regards
Johannes Meixner
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