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 > > Can anyone give an advice on which direction I should take? Thank you! > > -- > Best regards, > Coiby >
