Hi Hans, Sorry, now I was being slow as well. On Thu, Sep 20, 2018 at 07:31:43PM +0200, Hans de Goede wrote: > Hi, > > I completely missed this mail earlier, sorry. > > Thank you Benjamin for pointing this out to me. > > On 03-08-18 02:31, Dmitry Torokhov wrote: > > Hi Hans, > > > > On Tue, Jul 31, 2018 at 01:19:57PM +0200, Hans de Goede wrote: > > > Some touchscreens, depending on the firmware and/or the digitizer report > > > coordinates which never reach 0 along one or both of their axis. > > > > > > This has been seen for example on the Silead touchscreens on a Onda V891w > > > and a Point of View mobii TAB-P800w(v2.0). > > > > > > This commits documents 2 new touchscreen properties for communicating > > > the minimum reported values to the OS: touchscreen-min-x and -min-y. > > > > > > This commit also drop the (in pixels) comment from the documentation > > > of the touchscreen-size-x and touchscreen-size-y properties. This comment > > > suggests that there is a relation between the range of reported > > > coordinates and the display resolution, which is only true for some > > > devices. The (in pixels) comment is replaced with "(maximum x coordinate > > > reported + 1)" to mirror the language describing the new touchscreen-min-x > > > and -min-y properties. > > > > I am concerned that people will not read the documentation carefully and > > will treat it as true size, since it is what in the name. Maybe we > > should say that it is size of usable area, in device units, and that > > maximum reported coordinate is "touchscreen-min-x + touchscreen-size-x - > > 1"? > > Not sure what you mean with "true size" but in the implementation > from this series, the maximum coordinated reported is (touchscreen-size-x - 1) > not (touchscreen-min-x + touchscreen-size-x - 1) as you suggest. > > Basically what this series does is set: > > input_absinfo.minimum to the new touchscreen-min-x value (or 0 if not specified) > input_absinfo.maximum to touchscreen-size-x - 1 as we've always done. > > So the usable range / the range mapping from one screen edge to the other is: > > touchscreen-min-x - (touchscreen-size-x - 1) > > Which matches with the dt bindings doc after this patch, which > reads after this patch: > > - touchscreen-min-x : minimum x coordinate reported (0 if not set) > - touchscreen-min-y : minimum y coordinate reported (0 if not set) > - touchscreen-size-x : horizontal resolution of touchscreen > (maximum x coordinate reported + 1) > - touchscreen-size-y : vertical resolution of touchscreen > (maximum y coordinate reported + 1) > > I hope this clarifies things and if you want to change anything let > me know. Right, except that my concern is that people do not read documentation, and therefore will not realize that touchscreen-size-x is not the "true" what I called it, or what you call usable range, but rather maximum coordinate (-1). IOW I am concerned that if we have a device with 640x480 screen for example, and touch controller reporting coordinates with offset of 20, someone will specify: touchscreen-min-x = 20 touchscreen-size-x = 640 (because that's their screen size) and will not notice for some reason and later quirk it in their software. So I was asking if we should accommodate this, and actually set up max on axis as "touchscreen-min-x + touchscreen-size-x - 1". It will still be compatible with current bindings (having effectively min of 0), but to me better reflects the name of the parameter - size of the screen. Please let me know if this makes any sense to you. Thanks. -- Dmitry
