Hi Chris, Am Sonntag, 6. November 2011, 17:00:44 schrieb Chris Bagwell: > On Sun, Nov 6, 2011 at 3:32 AM, Alcides Viamontes Esquivel > > <a.viamontes.esqui...@gmail.com> wrote: > > Hi guys, > > > > I would like to say thanks for your wonderful job in supporting Wacom > > tablets. > > > > I got one CTH-470 yesterday and could get it cranking thanks to the > > work of Chris Bagwell > > (http://sourceforge.net/mailarchive/message.php?msg_id=28204872) , but > > I found some sort of bug which I think is related to that thread in > > GIMP discussion list but that also affects all other uses of the pen > > in this tablet: the cursor jumps some times (all > > coordinates/distance/pressures and a button touch=0) when dragging the > > stylus for a while. This doesn't happen in Windows, so I assumed it > > was some sort of software problem.
I noticed the same bug and Alcide's version fixed that issue for me (for now :-). > > I suspect that the real bug is somewhere in the way the packets are > > classified, and that somehow wacom_bpt_pen is processing a packet > > which is not for her. But I'm really not a kernel developer, so, I > > would appreciate any hints (in particular, how do you trace from > > inside a kernel module?). > > What code did you add to handle this? Do you ignore the whole packet > (do a return) if data[1] == 0? In wacom_bpt_pen() his code jumped out with "return 1" if (data[1] & 0x20 == 0). > I need to understand a little more whats going on in the big picture. > If we did get this unwanted packets, the current driver should be > telling xf86-input-wacom that the pen when out of proximity and then > when next packet comes that is valid it will tell xf86-input-wacom > that its back in proximity and with good values. > > Since we do not move the cursor while out of proximity and presumably > have valid data for next packets, I'd think no issue should be seen > beyond some pauses in drawing. > > So to really see whats happening, you may need to write some debug > code that does a printk() for 1st packet when data[1] == 0 and then > also printk() for the next 5 valid packets as well to see what their > values are. I added a printk at the top of wacom_bpt_pen() and sent data[0]...data[8] to logfile (see attachment). If the packet is ignored by "return 1" another log message "IGNORED DATA" has been emitted. Interesting is the part around Nov 6 17:42:59. The C0 package gets emitted every 5 seconds regardless if the stylus is in range of the tablet or not. Do you need any further information? Cheers Sönke
syslog.log.gz
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