Hi Neeraj, On Wed, Nov 13, 2019 at 4:11 AM Neeraj Upadhyay <neeraju@xxxxxxxxxxxxxx> wrote: > > Hi, > > I have one query regarding hid-multitouch.c driver and need your guidance on > how hid-multitouchc can restore/support the original behaviour, where, for > devices, for which application is not > HID_DG_TOUCHSCREEN/HID_DG_TOUCHPAD, and has > HID_DG_CONTACTID usage in its report, can still use generic input mappings. > > We are using kernel versions 4.14 , 4.19 respectively in 2 different > projects: > > 4.14: > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/hid/hid-multitouch.c?h=v4.14.153 > 4.19: > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/drivers/hid/hid-multitouch.c?h=v4.19.83 > > I checked the application for our hid device, it's HID_DG_PEN, device > also has a HID_DG_CONTACTID usage defined in > > its report. > > In 4.19, is_mt_collection is set to 'true'. All multitouch code paths or > input mapping is configured > > mt_allocate_report_data() > ... > for (n = 0; n < field->report_count; n++) { > if (field->usage[n].hid == HID_DG_CONTACTID) > rdata->is_mt_collection = true; // > is_mt_collection is set to 'true' > } > } > > mt_input_mapping() > ... > if (rdata->is_mt_collection) > return mt_touch_input_mapping(...) // > mt_touch_input_mapping() is called > > mt_event() > if (rdata && rdata->is_mt_collection) > return mt_touch_event(); // mt_touch_event() is called > > However, in 4.14, the behaviour was different, mt input mapping was done > only > for HID_DG_TOUCHSCREEN/HID_DG_TOUCHPAD , and because our hid device is > HID_DG_PEN, generic mappings were applied for it; with these settings, > device > responds to events. > > static int mt_input_mapping() > if (field->application == HID_DG_TOUCHSCREEN || > field->application == HID_DG_TOUCHPAD) > return mt_touch_input_mapping(); // This is not called. > > > mt_touch_input_mapping() > case HID_DG_CONTACTID: > mt_store_field(usage, td, hi); > td->touches_by_report++; > td->mt_report_id = field->report->id; // > mt_report_id is not set. > return 1; > > > Looks like this behaviour changed, with below commits: > > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/hid/hid-multitouch.c?h=v4.19.83&id=8dfe14b3b47ff832cb638731f9fc696a3a84f804 > 8dfe14b3b47f HID: multitouch: ditch mt_report_id > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/drivers/hid/hid-multitouch.c?h=v4.19.83&id=ba6b055e0f3b4ff4942e4ab273260affcfad9bff > ba6b055e0f3b HID: input: enable Totem on the Dell Canvas 27 > > Can you please suggest on how we can support/preserve the original > behaviour? Hmm, I would initially say that a firmware that exports Contact ID for a Pen is definitely wrong. The Contact ID usage has been introduced in https://www.usb.org/sites/default/files/hutrr34.pdf and is specifically for multi-touch, not multi pen. Anyway, couple of questions: - does the device supports multi-pen? - can you share the report descriptor and a few events when triggering this particular report (ideally with hid-recorder from https://gitlab.freedesktop.org/libevdev/hid-tools/ Cheers, Benjamin > > > Thanks > Neeraj > > -- > QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation >
