Re: Unsupported device message, Compliance C.2, part 4

Aras Vaichas wrote:
> Alan Stern wrote:
>>> "The USB-IF enforces a "no silent failure" rule. This means that an 
>>> implementation of USB must not appear broken to the consumer. In configurations 
>>> where the consumer's expectations are not met, either the peripheral or host 
>>> must provide appropriate and useful feedback to the consumer regarding the 
>>> problem."
>> In an embedded host, the system log probably isn't accessible to the
>> user.  Error messages would have to appear somewhere else -- although
>> just where would depend on the particular system.
> 
> I was just looking at sysfs and I noticed that when a known USB device is 
> plugged in that a "product" file is created in 
> /sys/devices/platform/at91_ohci/usb1/1-1/
> 
> An unknown device will not cause this file to be created, therefore that sounds 
> like a good signalling mechanism to me. This is something that I can work with.

Sorry about answering my own questions but we are in different timezones and I 
like to document the process.  :)

Here is a prototype script that creates a log message when an unknown USB 
device is inserted into a particular USB host socket. It could form the basis 
for a smarter system that can handle multiple host sockets and hubs.

---- SNIP ----

#!/bin/sh

BASE=/sys/devices/platform/at91_ohci/usb1/1-1

indicated=0
while [ 1 ]; do
     if [ $indicated == 0 ]; then
        if [ -d "$BASE" ]; then
            indicated=1
             if [ -f "$BASE/product" ]; then
                 logger "A known USB device has been inserted."
             else
                 logger "An unknown USB device has been inserted."
             fi
         fi
     else
         if [ ! -d "$BASE" ]; then
             indicated=0
         fi
     fi
     sleep 1
done





Aras

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