On Fri, Sep 4, 2020 at 4:59 PM Coiby Xu <coiby.xu@xxxxxxxxx> wrote: > > On Fri, Sep 04, 2020 at 10:16:51AM +0200, Benjamin Tissoires wrote: > >Hi, > > > >On Tue, Aug 11, 2020 at 11:15 AM Coiby Xu <coiby.xu@xxxxxxxxx> wrote: > >> > >> Hi, > >> > >> I'm working on a touchpad device issue as reported on > >> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1887190. > >> > >> This touchpad device MSFT0001:00 04F3:Touchpad should be handled by > >> hid_rmi. But currently hid-core.c chooses hid_multitouch by mistake, > >> > >> 1. When scanning this device's report descriptor, HID_DG_CONTACTID > >> usage is found. Thus group HID_GROUP_MULTITOUCH is assigned to > >> the device. > >> 2. The flag HID_SCAN_FLAG_MT_WIN_8 is also found. Thus group > >> HID_GROUP_MULTITOUCH_WIN_8 is assigned to the device. > >> 3. hid-multitouch.c claims handling devices with the group of > >> HID_GROUP_MULTITOUCH_WIN_8 > >> > >> static const struct hid_device_id mt_devices[] = { > >> /* Generic MT device */ > >> { HID_DEVICE(HID_BUS_ANY, HID_GROUP_MULTITOUCH, HID_ANY_ID, HID_ANY_ID) }, > >> > >> /* Generic Win 8 certified MT device */ > >> { .driver_data = MT_CLS_WIN_8, > >> HID_DEVICE(HID_BUS_ANY, HID_GROUP_MULTITOUCH_WIN_8, > >> HID_ANY_ID, HID_ANY_ID) }, > >> { } > >> }; > >> > >> There are several potential solutions, > >> - Let the device vendor fix this problem since this device's report > >> descriptor shouldn't have the HID_DG_CONTACTID usage. > >> - Make it a special case by setting the device's group to > >> HID_GROUP_RMI in hid_scan_report when vendor id and product ID > >> are matched. > >> - hid-quirks.c seems to be designed to handle special cases, is it > >> suitable for this case? > > > >AFAIU, the touchpad doesn't work at all with hid-multitouch. So I > >guess the best is to add the VID/PID to hid-quirks.c in > >hid_have_special_driver[], and add it to the hid-rmi driver too. > >This way, you will ensure hid-rmi will pick up the device all the time. > > > >Cheers, > >Benjamin > > Thank you for the advice! I have exactly adopted this approach by looking > at commit e9287099ba6539bccb20cd791269186f3ae28b85 > ("HID: rmi: Add support for the touchpad in the Razer Blade 14 laptop") > as an example. > > My previous email is a bit misleading because 0x04F3 is the vendor code > of ELAN while hid-rmi is for the Synaptics touchpad. And actually this > laptop model of Lenovo Legion-5 15ARH05 is shipped with both kinds of > touchpads, > > - for the Synaptics touchpad, hid-rmi could almost handle it perfectly > except the clicking is not sensitive enough. I need to let my finger > linger on the touchpad for a while. I notice when I click on the touchpad, > an HID report would be received by hid-recorder. But evtest couldn't receive > any EV_ event. If hid-multitouch is handling the device, the cursor > won't move but 2-4 finger touching events could still be received by > evtest. > > - for the ELAN touchpad, only HID reporters can be read and parsed by > hid-core then two input devices (mouse and touchpad) could created by > hid-multitouch as seen from /proc/bus/input/devices. But hid-recorder > could never get any HID report. huh. So in both cases you have a buggy touchpad with hid-multitouch :( Do both touchpads share the same VID/PID? If so, this is going to be interesting to decide how any of those touchpad should be handled. > > AFAIU, isn't hid-multitouch supposed to be the implementation of Windows > Precision Touchpad? yes, it works for most of those. The only ones that are not working are usually because OEM or device makers tend to do "fun" things. > And since Precision touchpad is mandatory for > Windows 10 notebooks and this laptop model of Lenovo Legion-5 15ARH05 > seem to have been certificated by Windows 10, does it mean by theory > hid-multiouch could handle these two touchpad devices? Well, it should, yes, but it clearly can not. You can try to give a try at hid-recorder from https://gitlab.freedesktop.org/libevdev/hid-tools. This will show what is actually exported by the hardware before any processing by the kernel. Maybe there is a new simple thing to do in hid-multitouch to handle those devices. Also, last time I heard, Synaptics dropped the use of hid-rmi in favor of hid-multitouch. Any hid-rmi touchpad should be able to use hid-multitouch, as this is the preferred way on Windows. But sometimes the various teams decide to change the rules. > > Anyway, it seems I need to install Windows Driver Kit to capture&analyze > HID reports to see what's happening. Or do you have any suggestion? Unless it changed recently (I think I have seen something like that recently), I had to write a I2C man-in-the-middle to dump the logs from Windows. Project is at https://github.com/bentiss/SimplePeripheralBusProbe and requires a little bit of manual work to be able to start capturing data :( Cheers, Benjamin > > -- > Best regards, > Coiby >
