Hello,

I mailed already about a 1/4 years ago.
My last post referred to the changed string length descriptor read length in
drivers/usb/core/message.c that reads (at about line 1250)

  len=tbuf[0];

As known, some devices as my NIASH scanner, and the scanners of some fellow
users won't work any longer with stock kernels, due  to a code change that
formerly treated the length of the string as if it was "255".

In all kernels I used so far, I changed this code to

  len=tbuf[0]=255;

made my device works again.
This (still) pending patch is known as "PATCH: (as214) Avoid babble errors
when reading strings"

Since the mentioned change (len instead of 255), the according forums are
flood with postings about non-working scanners.
Some of these "posters" are real newbies that are not able to compile,
install, etc their own kernels.
But stock-kernels will never work with these scanners. 

I understand that there are severe reasons to keep the code changed as it
is, because newer devices will work more reliable with  this change.

But - and please see this only as an idea of the mind of a non skilled
kernel hacker - would it be possible to make a pseudo device  at
"/proc/whatever" available to tell the kernel by a simple 
"cat 1 >> /proc/whatever" 
or 
"cat 0 >> /proc/whatever"
, which string length descriptor interpretation would be the appropriate for
the current system setup?
It would then be up to the users to decide, which strategy to follow, to
make the system work with their hardware.
I can say that in my setup a digital camera, a game pad, an USB-ADSL-modem
and a USB-printer work (with the 255-len) properly  without an y noticed
interference.

As I wrote... Changing the kernel is an option for me, but not for new Linux
users.

Thank you all for your skill and patience

Ullrich



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