On Wed, May 26, 2010 at 08:59:35AM -0700, Ping Cheng wrote: > On Tue, May 25, 2010 at 1:23 PM, Dmitry Torokhov > <dmitry.torokhov@xxxxxxxxx> wrote: > > On Tue, May 25, 2010 at 09:52:29PM +0200, Henrik Rydberg wrote: > >> Dmitry Torokhov wrote: > >> > Hi Henrik, > >> > > >> > On Tue, May 25, 2010 at 01:52:57PM +0200, Henrik Rydberg wrote: > >> >> These patches are in response to the discussion about input state > >> >> retrieval. > >> >> > >> >> The current EVIOCGABS method does not work with MT slots. These > >> >> patches provides a mechanism where a slot is first selected via a call > >> >> to EVIOCSABS, after which the corresponding MT events can be extracted > >> >> with calls to EVIOCGABS. > >> >> > >> >> The symmetric operation, to set the MT state via EVIOCSABS, seems to > >> >> violate input data integrity, and is therefore not implemented. > >> >> > >> > > >> > This looks sane, however the question remains - is there any users for > >> > this data? Like I mentioned, I can see the need to fetch state of > >> > switches and ranges of absolute axis, and even non-multitouch ABS values > >> > (due to the fact that some input devices, like sliders, may stay in a > >> > certain position for long periods of time), but I expect multitouch data > >> > to be "refreshed" very quickly. > >> > > >> > Thanks. > >> > > >> > >> There were some voices addressing this issue, and the patches are here, > >> available for whomever to pick up. Drop them if you wish, I will not send them anew. > >> > > > > I'll save them in my queue but will hold off applying until I hear > > userspace folks requesting such functionality. > > Hi Dmitry, > > You do have a valid point - the (x,y) from a touch object would most > likely change all the time. Even if the object itself is in a steady > state on the digitizer, i.e., without any intentional movement, the > electronic noise would most likely lead to some (x,y) changes. So, the > chance that we need to retrieve (x,y) is rare. > > However, it is possibe that when X driver starts, an object was > already on the digitizer. And the digitizer is of such a high quality > :), it filtered all the noises so we can not locate the touch without > a EVIOCGABS call. > > Plus, from a pure coding/development point of view, it is not a bad > practice to provide the equivalent features for _MT_ support as we did > for the existing input devices. At least, it doesn't hurt to make the > support consistent across devices/tools (considering touch as a new > input device/tool). Ping, I did not say that there was a problem with the patch, I agree with it. However if no one using this - why should we bother? Will _you_ utilize this functionality in Wacom X driver? If so let me know and I will merge it. -- 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
