[sane-devel] Scanner failure when connected via USB3

[Mike Cloaked]

On Fri, Oct 31, 2014 at 8:58 AM, Olaf Meeuwissen <olaf.meeuwissen at avasys.jp>
wrote:

> Hi Mike,
>
> First of all, apologies for the somewhat belated reply.  I will try to
> piece all the bits from your flurry of mails that followed this one
> together in this reply.
>
> snip


> I had an admittedly cursory look at your USB captures.  What struck me
> is the enormous amount of USB control messages in
> wireshark-start-xsane-acquire-preview-crash.pcapng, some 4234 packets
> out of a total of 4326 captured.  That's 97.9% of the packets.  While I
> find that surprising, I don't know whether it is abnormal.  Maybe
> someone with more knowledge of USB3 Linux support can chime in here?
>
>
> snip


> Please note that I am just thinking out loud (and don't have a lot of
> experience in this area).
>
> I'll see if I can find some time to play around with another scanner and
> reproduce some of what you're seeing.
>
> Hope this helps,
>

Thank you for your extensive thoughts. No problem with delayed reply - most
of us only have a fraction of our time to work on these things.

It does seem that this is not going to be a simple issue to resolve, with
exploration needed on several different parts of the whole system, so
nailing where the fundamental problem lies could need fixes in the kernel,
the usb libraries or in sane code.  Either way it would be useful to have
independent tests and more diagnostics. I did also read up more about mce
errors and it seems that there is a package that can be installed that will
allow getting more detailed logs from mce errors.  I am not sure that this
will yield anything definitive though and it may be more of a consequence
of errors elsewhere.

Anyway in due course if this could be explored further and gain traction on
where the fixes are needed, then it might help quite a few people who are
driving usb2 scanners (the vast majority) through usb3 interfaces, which
will become a higher fraction of the usage cases for user machines as time
passes.

-- 
mike c
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