2007/2/23, Magnus Vigerlöf <[EMAIL PROTECTED]>: > On Friday 23 February 2007 09:26, Pablo Giménez wrote: > [...] > > > I am looking into support for true hotplug of wacom tablets for the next > > > release from Xorg (7.3), and there are a few things that needs to be > > > changed in our driver if that should work as we want. *Maybe* those > > > changes can help in this case. When I look at the code I doubt it, but > > > there's always a possibility.. > > > > Maybe is a problem in the X side. > > I can guess that the problem is related to open/close the wacom device. > > Maybe when you first enter your session the new Xsession opens the > > wacom device, take the ownership of it. When you change the new > > session do the same, here is my doubh, why? it can happen. If the > > second user can access to a previously opened wacom device and take th > > eownership, the it will be logicla that when you return to your > > previous session you can again open the wacom device. > > I am not a kernel or device driver expert so maybe I am complitely in > > a mistake. > > Mmmm... You're basically correct. > > When the wacom X-driver opens the wacom device (/dev/input/eventX) is has to > GRAB the device to prevent the underlying hardware from sending the movment > information to /dev/input/mice [1] (that's why you can use the tablet even if > you haven't defined an InputDevice specifically in X for it). If the driver > doesn't do this, movement information will come from two different channels > and X will be confused. Mostly this will manifest itself in very strange > behaviour in programs that uses the extended information the devices defined > for the tablet can provide (gimp and other paint programs mostly). Thanks magnus for your excellent explanation. Maybe something could be done from the wacom driver side, I don't in a new kernel device or in the X module. For the moment your kernel module seems to be the unique solution. I hope I can take a little of time to test in my machines. > > So, the first X-server open and grab the device. When the second server starts > it switches to a different VT and this causes the X-server to close the wacom > device so the second X-server can open and grab it. So far no problem. But > when you switch back to the first X-server this doesn't happend in a proper > way for some reason and this causes the lack of movment of the cursor in that > X-server when you use it. > > This is about as far as I got last time I looked on it. Hope it helps the > understanding what might go on beneath the hood. If anybody has more > information that could help us fix this in the ordinary driver I'd be very > happy. > > The /dev/input/eventX devices only allows one process to GRAB the device at > any given time. My device will allow multiple processes to GRAB the device at > the same time. The only thing the GRAB will do is to prevent the underlying > hardware to send the movement information to the /dev/input/mice device as > well. This is the only difference in the behaviour of the two device > drivers.. > > Maybe it is possible to skip the GRAB part for the X-driver once the hotplug > has made it's way into the X-server (and we have fixed the support for it) as > it doesn't need to listen to /dev/input/mice anymore (it can use one of the > specific mouse-devices instead). I've seen arguments for keeping it though so > we'll have to wait and see what will happend. > > Cheers > Magnus V > > [1] /dev/input/mice is a hack in the kernel to make it possible for the > X-server to support hutplug of USB, PS/2, ... mice, tablets, etc in the > current releases of X. It aggregates all mouse devices into one device which > is always present and can always be opened. Adding a mouse will therefore > only add a driver that will send information through this device as well as > it's own mouseX-device. >
-- Un saludo Best Regards Pablo Giménez ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Linuxwacom-discuss mailing list Linuxwacom-discuss@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linuxwacom-discuss
