<div dir="ltr"><div><div><div>Hello </div>The detection of the library is automatically done during the configuration. The option is not useful. And the use #ifdef HAVE_MTDEV seems to be simpler, if in the future this feature will disappear. </div>What I do ? I send again or I increase the complexity. </div>Marc. </div><div class="gmail_extra"> <div class="gmail_quote">2013/6/11 Benjamin Tissoires <<a href="mailto:benjamin.tissoires@gmail.com" target="_blank">benjamin.tissoires@gmail.com</a>> <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="HOEnZb"><div class="h5">On Tue, Jun 11, 2013 at 12:40 PM, Pekka Paalanen <<a href="mailto:ppaalanen@gmail.com">ppaalanen@gmail.com</a>> wrote: > On Tue, 11 Jun 2013 12:10:05 +0200 > Benjamin Tissoires <<a href="mailto:benjamin.tissoires@gmail.com">benjamin.tissoires@gmail.com</a>> wrote: > >> On Tue, Jun 11, 2013 at 9:41 AM, Pekka Paalanen <<a href="mailto:ppaalanen@gmail.com">ppaalanen@gmail.com</a>> wrote: >> > On Tue, 11 Jun 2013 09:01:48 +0200 >> > Benjamin Tissoires <<a href="mailto:benjamin.tissoires@gmail.com">benjamin.tissoires@gmail.com</a>> wrote: >> > >> >> On Mon, Jun 10, 2013 at 8:42 AM, Pekka Paalanen <<a href="mailto:ppaalanen@gmail.com">ppaalanen@gmail.com</a>> wrote: >> >> > On Fri, 7 Jun 2013 12:11:14 +0200 >> >> > Marc Chalain <<a href="mailto:marc.chalain@gmail.com">marc.chalain@gmail.com</a>> wrote: >> >> > >> >> >> mtdev is not necessary on some device (desktop or set-top-box). For >> >> >> embedded solution the minimum of dependencies is required. "configure" >> >> >> accepts the --disable-mtdev option. >> >> > >> >> > Hi Marc, >> >> > >> >> > with this patch, if weston is compiled with --disable-mtdev, it looks >> >> > like it will still happily open multitouch devices, expose them to >> >> > Wayland clients, and feed them garbage or fail or whatever. Right? >> >> >> >> Hi Pekka, >> >> >> >> no. mtdev is a compatibility layer for converting very rare >> >> touchscreen using the multitouch protocol A into the mostly used >> >> multitouch protocol B. >> >> To my mind, only legacy devices (ntrig 0001 and few others) use the protocol A. >> >> So without mtdev, wayland will open and handle most of the multitouch >> >> screen happily. >> >> >> >> > >> >> > I think the proper approach is to change the configure option into >> >> > --disable-multitouch or --disable-touchscreen, which would not only >> >> > drop the dependency to mtdev, but also make Weston ignore all >> >> > touchscreen devices since it will not be able to handle them. >> >> >> >> Without mtdev, wayland should only ignore multitouch screen not >> >> presenting the ABS_MT_SLOT axis. >> >> Those relying on SYN_MT_REPORT do not provide tracking (which is done by mtdev). >> >> >> >> So my guess is that if you detect multitouch screens by looking at >> >> ABS_MT_SLOT, then everything will be fine whether or not you have >> >> mtdev: >> >> - multitouch B screens will correctly be handled >> >> - multitouch A screens will be processed as a single touch screen, >> >> which is not a problem because the kernel provides single touch >> >> emulation since the early days of multitouch. And if mtdev is present, >> >> then it will show the ABS_MT_SLOT axis, leading to the previous case. >> >> >> >> Bonus point, mtdev has not been updated since a long time, and is >> >> missing the bits allowing you to retrieve the initial per-slot states. >> >> And you may find useful to retrieve the current states when weston >> >> launches. >> > >> > Thank you for clarifying that, Benjamin. >> > >> > Does this mean that we need explicit single-touch support in Weston? >> >> After giving a quick look at evdev.c, it appears that single touch >> devices are already treated in the same way tablets (with stylus) are. >> So, single touch devices are seen from weston in the same way they >> have been seen in Xorg since the beginning: as absolute input devices. >> >> Then, it's just a matter of deciding whether we want to inform the >> client if the source of the event is a finger or a pen. > > Right... except we do not support tablets at all at the moment. We miss > the whole protocol for tablets. Wayland (not just Weston) only has > support for touchscreens so far, in addition to keyboards and relative > pointing devices. > > evdev.c's device type recognition is just a handful of ad hoc > heuristics for now, written only for touschscreens, keyboards, and > mice/touchpads, and trying to ignore everything else. </div></div>Right, the current recognition seems to be even worth than what udev does (in the sense that it is not a complete characterization, no offense). I followed the thread from David Herrman about libinputmapper and hopefully, we will get in the end a more robust detection of input devices. <div class="im"> > >> > I don't think we have that yet. Everything touchy goes through mtdev, >> > which makes also real single-touch devices look like multitouch devices >> > except they never report more than one contact. Do I understand that >> > right? >> >> evdev.c detects "touch" devices by looking at ABS_MT_SLOT. But mtdev >> does not transform single touch device into pseudo-multitouch devices. >> So I would say that those single touch devices are not treated as >> "touch" today. > > Ok, so probably they would not work anyway atm. > > Which means that dropping mtdev loses only some rare multitouch > devices, which do not advertise ABS_MT_SLOT, and hence will get > properly ignored. Right? </div>right :) <div class="im"> > > I wonder if single-touch devices get detected as touchpads. Depends on > if they have any keys, it seems. :-) </div>They should not: the udev mapping for touchpads rely on BTN_TOOL_FINGER, so normally, the kernel will not set this property for single touch screen (we try to not break existing in the kernel, and the existing detection mechanism rely on BTN_TOOL_FINGER...). But again, this is the theory :) Cheers, Benjamin <div class="HOEnZb"><div class="h5"> > >> > Marc, in any case, I think you should check that Weston correctly >> > ignores touch devices it cannot support without mtdev, as per >> > Benjamin's instructions above. >> > >> > Retrieving current state is a matter for another time. >> > >> >> Oh yes. FYI, I still did not found the time to finalize the patches for Xorg :) > > > Thanks, > pq </div></div></blockquote></div> </div>