On Tue, Nov 04, 2014 at 09:38:38AM -0800, Ping Cheng wrote: > Hi Dmitry, > > On Tue, Nov 4, 2014 at 12:08 AM, Dmitry Torokhov > <dmitry.torokhov@xxxxxxxxx> wrote: > > On Sat, Nov 01, 2014 at 08:40:19AM +0100, Hans Petter Selasky wrote: > >> On 11/01/14 00:27, Ping Cheng wrote: > >> >If touch_input is NULL on FreeBSD, you need to figure out the root > >> >cause. Checking on touch_input itself would not fix the root cause... > >> > >> Right. > >> > >> The root cause is that FreeBSD launches two instances of the driver, > >> running in two different userland processes, for the two different > >> Wacom interfaces on a common USB device. In Linux the wacom > >> interface drivers are running from the same kernel, and can share > >> the data in question, but in FreeBSD's webcamd emulation, this > >> doesn't work. Then the first wacom probe call would have to grab the > >> second interface. > >> > >> Technically speaking this is a FreeBSD only problem and I plan to > >> deliver a patch with the webcamd software to fix this, like already > >> suggested to you guys. This situation can also happen on Linux in > >> case of a "BadUSB" device. That's why I think that the NULL check > >> should be upstreamed. > > > > Hmm, looking at this again it seems that we just cross our fingers and > > hope that both interfaces are enumerated by the time we get event data > > from the device. I do not think this is quite safe. We probably should > > be checking the overall state of probing (i.e. whether we are done > > probing both interfaces) before processing data for the device. > > Are you going to make a patch to address the issue? Not in the nearest future, sorry. > > > Or maybe we should just forcibly try claiming secondary interface > > while probing primary instead of messing with shared data item. > > If we incorporate the above idea into a patch, we need to keep in mind > that not all tablets support touch data. So, not all tablets have two > interfaces. Right, but we do know the models that use multiple interfaces, right? -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
