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? > 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. Cheers, Ping > That won't help Hans though: the devices do use 2 interfaces in tandem, > treating them separately will result in incorrect behavior. > > Thanks. > > -- > 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
