Re: [PATCH 2.6.20 1/1] usb/input updated aiptek tablet driver

On Fri, 09 Mar 2007 20:27:30 -0600, Bryan Headley <[email protected]> wrote:

> >> +	/* We now will look for the evdev device which is mapped to
> >> +	 * the tablet. The partial name is kept in the link list of
> >> +	 * input_handles associated with this input device.
> >> +	 * What identifies an evdev input_handler is that it begins
> >> +	 * with 'event', continues with a digit, and that in turn
> >> +	 * is mapped to /{devfs}/input/eventN.
> >> +	 */
> >> +	inputdev = aiptek->inputdev;
> >> +	list_for_each_safe(node, next, &inputdev->h_list) {
> >> +		inputhandle = to_handle(node);
> >> +		if (strncmp(inputhandle->name, "event", 5) == 0) {
> >> +			strcpy(aiptek->features.inputPath,
> >> +			       inputhandle->name);
> >> +			break;
> >> +		}
> >> +	}
> > 
> > This is something I wanted to discuss with aiptek developers, because
> > of races walking h_list outside of input core itself, where you do not
> > have access to core's locks. This cannot be safe.
> > 
> > Is it feasible to get rid of this feature altogether?
> 
> Problem is, the tablet has to be at a /dev/entry that's knowable to the
> xorg driver. The original thought was, we figure out which
> /dev/input/eventX device entry the driver/device is mapped to, expose
> that mapping to one of our (many) sysfs files, then do a "sed
> 's_AIPTEK_DEVICE_/dev/input/eventX_g' /etc/xorg.conf.master >
> /etc/xorg.conf" ...

I see, thanks for explaining. So, the question is, can you replace
that sed script with a perl scriptlet which reads /sys/class/input/input*
and does the same thing? I understand that following the maze of links
is somewhat annoying, but perhaps all it takes is (in bash):

 cd /sys/class/input
 for i in input*; do
   if [ "$(basename $(ls -L $i/device/driver))" == "aiptek" ]; do
     goto found
   fi
 done

There's a question of compatibility, of course, but perhaps the replacement
script can be rolled out over the space of a couple of kernel releases?

-- Pete

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