Hi Benjamin, Thanks for the response. It is my ignorance that should be excused as I have shown/will show that I am the novice with regards to USB HID and multitouch in this forum :) I´ll continue interleaving additional comments below. -Pablo > -----Original Message----- > From: Benjamin Tissoires [mailto:benjamin.tissoires@xxxxxxxxx] > Sent: den 27 maj 2011 18:10 > To: Pablo Cases > Cc: Stéphane Chatty; Henrik Rydberg; Jiri Kosina; linux- > input@xxxxxxxxxxxxxxx > Subject: Re: g_hid and hid-multitouch compatibility? > > Hi Pablo, > > Adding Stéphane, Henrik and Jiri in CC. > > On Fri, May 27, 2011 at 17:33, Pablo Cases <pablo.cases@xxxxxxxxxxxx> > wrote: > > > > Hi all, > > > > I have searched the net and the archives of linux-input for > information on how to use the Linux g_hid kernel module on a device and > the hid-multitouch kernel module on a host to communicate multitouch > events. But unfortunately I can only get single touch working. > > Excuse my ignorance, I didn't know g_hid existed before your mail. If > I understand it well enough, it's an hid emulation from user-space. > Are you trying to inject events from a device in user-space to the > kernel? If so, I think it would be easier to use uinput. And the funny > think was that I'm currently writing a small lib to inject mulitouch > events in a uinput device in an easier way. > Maybe I misunderstand your explanation above but we´re not running g_hid and hid-multitouch on the same system. We have a separate hardware USB device running Linux with the g_hid kernel module loaded. On this device we then have (thanks to g_hid) a userspace file called /dev/hidg0 that we can write USB HID input reports to, which then will be sent through the device's gadget usb framework, through an physical USB cable, to a separate PC host running hid-multitouch. > > > > Q: Has anyone successfully completed a g_hid <-> hid-multitouch > setup? And is there a description somewhere of such setup? > > I don't think so, hid-multitouch is really new (since 2.6.38, and was > not very generic at this time). > > > Q: Is the Windows 7 multitouch USB HID descriptor the correct one to > use also for Linux hid-multitouch? Or is some tweaking necessary? > > Normally, any valid Windows 7 multitouch USB HID descriptor can be > handled by hid-multitouch. > But it's more the events that are sent to hid-multitouch that will > tell if your device is compatible or not. > > > > > DETAILED DESCRIPTION BELOW > > The device is a Linux device that uses g_hid (currently 2.6.37 > kernel) and a USB HID Report Descriptor for multitouch using two-touch > parallel mode according to Microsoft document > http://msdn.microsoft.com/en-us/windows/hardware/gg487437. > > > > On the host (ubuntu 11.04, 2.6.38 kernel) I register dynamically > according to the description at http://lii- > enac.fr/en/architecture/linux-input/multitouch-ubuntu-howto.html. Using > the events/rdesc files in debugfs on Ubuntu 11.04 I have validated the > parsing of the report descriptor and the input reports. > > This is really a bad idea to use these howto with ubuntu 11.04 ATM. I > didn't found the time to update this stuff, and this branch can not be > used in ubuntu 11.04 (it contains code for 2.6.35 only, and there were > changes in the hid layer after). If you only used the part "How to add > your device to hid-multitouch from the user space" without updating > your hid module, then it's as if you have'nt done anything (the > generic hid module can not autodetect multitouch devices). Currently I am using the hid-multitouch code as existing in the source distribution of a 2.6.38 Ubuntu 11.04 fetched through apt-get. In the page referred to above I have only used the "How to add your device to hid-multitouch from the user space", and not the 2.6.35 related parts. Ok, so for autodetection of multitouch devices to work I need to update the hid-multitouch module to a newer version (than was available in 2.6.38), preferably head on a git master branch somewhere? Another option is to add a static configuration field in hid-multitouch and hid-ids.h for my USB device's VID/PID. But then again, maybe it's better to do that on the latest available code as well? > > > > Example multitouch input report from > /sys/kernel/debug/hid/0003:xxxx:yyyy.0002/events looks correct: > > report (size 14) (numbered) = 05 03 00 a5 12 32 0e 03 01 99 14 32 0e > 02 > > Digitizers.TipSwitch = 1 > > Digitizers.InRange = 1 > > Digitizers.ContactID = 0 > > GenericDesktop.X = 4773 > > GenericDesktop.Y = 3634 > > Digitizers.TipSwitch = 1 > > Digitizers.InRange = 1 > > Digitizers.ContactID = 1 > > GenericDesktop.X = 5273 > > GenericDesktop.Y = 3634 > > Digitizers.ContactCount = 2 > > > > Most of the time, the problematic part comes from the releases. But > it's a good start. With "releases" I assume you mean the finger removal from the touch surface, like a "touch-up" event? I have not implemented that part yet, but our Microsoft contact informed us that for Windows 7 compatibility it should be reported as a final touch report with TipSwitch = 0 InRange = 1 Is this applicable to hid-multitouch too? > > The first touch in the report is correctly presented both on Windows > and on Ubuntu 11.04 (using ENAC's mtdiag tool with a minor tweak to > display data from all devices not just multitouch ones). I can see in > the debugfs files that the data for the second touch data is correctly > transferred and interpreted (see above), but the mapping to the linux > input system seems a bit strange though (see below). My guess is that I > have not been correctly registered as a multitouch device. I'm assuming > this also because I cannot see any activity from the hid-multitouch > module other than it being initialized when I connect my device > (probably another reason for the needed tweak in mtdiag above). > > > > Example mapping from /sys/kernel/debug/hid/0003:xxxx:yyyy.0002/rdesc > that does not look entirely correct for the second touch: > > Digitizers.TipSwitch ---> Key.Touch > > Digitizers.InRange ---> Key.ToolPen > > Digitizers.ContactID ---> Absolute.Misc > > GenericDesktop.X ---> Absolute.X > > GenericDesktop.Y ---> Absolute.Y > > Digitizers.TipSwitch ---> Key.Touch > > Digitizers.InRange ---> Key.ToolRubber > > Digitizers.ContactID ---> Absolute.? > > GenericDesktop.X ---> Absolute.Z > > GenericDesktop.Y ---> Absolute.Rx > > This means that your device is handled by the generic usbhid and not > hid-multitouch. That is what troubles me. I can see in the host's dmesg that "generic-usb" seems to be the driver chosen for my device when it is connected to the host. And according to your comment above I might not have correctly registered my device in hid-multitouch which would be the source of the problem... As a side note; I have sprinkled printk() here and there hid-multitouch.c and hid-core.c. While running the code I can only see that mt_init() and mt_exit() are called during module loading/unloading; never do I see any evidence of that the probing or mapping functions in hid-multitouch are used, only the generic usb parts are used for parsing the report descriptors and input reports. Could you point me to the location in the code where the decision is taken to use the hid-multitouch driver for a hid-multitouch supported device? I'm guessing it is somewhere in hid-core.c but I have not been able to pinpoint the location exactly. I could use this location as a start point to backtrace why we're not considered as a hid-multitouch supported device. > If you are trying to inject events from the user space, I strongly > recommend to use uinput instead. Let me know if you want to have my > little uinput-multitouch lib. > > Cheers, > Benjamin > > > Digitizers.ContactCount ---> Absolute.? > > Button.0001 ---> Key.LeftBtn > > Button.0002 ---> Key.RightBtn > > Button.0003 ---> Key.MiddleBtn > > GenericDesktop.X ---> Relative.X > > GenericDesktop.Y ---> Relative.Y > > GenericDesktop.Wheel ---> Relative.Wheel > > > > > > Regards, > > Pablo Cases > > > > ------------------------- > > Pablo Cases, M.Sc. > > Development Engineer Software > > FlatFrog Laboratories AB > > Magistratsvägen 10 > > 22643 Lund > > Sweden > > Tel: +46 708 393816 > > Mail: pc@xxxxxxxxxxxx > > Web: www.flatfrog.com > > -- > > 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 > > -- 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
