Hi Benjamin,
Sorry for the delay, was waiting for the required information from our team.
On 11/13/2019 3:00 PM, Benjamin Tissoires wrote:
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?
Actually the device is a selfie stick device:
https://item.jd.com/33082497741.html
It does not support 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/
Report descriptor is below:
05 0d 09 02 a1 01 85 01 09 22 a1 02 09 42 15 00 25 01 75 01 95 01 81 02
09 32 81 02 95 06 81 03 75 08 09 51 95 01 81 02 05 01 26 ff 0f 75 10 55
0e 65 33 09 30 35 00 46 b5 04 81 02 46 8a 03 09 31 81 02 c0 05 0d 09 54
95 01 75 08 81 02 85 08 09 55 25 05 b1 02 c0 05 0c 09 01 a1 01 85 02 09
e9 09 ea 0a ae 01 09 e2 09 30 15 01 25 0c 75 10 95 01 81 00 c0
Events were collected using getevent call in adb shell in android:
On 4.19
# getevent -l
add device 7: /dev/input/event6
name: "BLE-M1 UNKNOWN"
/dev/input/event6: EV_ABS ABS_MT_TRACKING_ID 00000000
/dev/input/event6: EV_ABS ABS_MT_POSITION_X 00000800
/dev/input/event6: EV_ABS ABS_MT_POSITION_Y 00000d60
/dev/input/event6: EV_KEY BTN_TOUCH DOWN
/dev/input/event6: EV_SYN SYN_REPORT 00000000
/dev/input/event6: EV_ABS ABS_MT_TRACKING_ID ffffffff
/dev/input/event6: EV_KEY BTN_TOUCH UP
/dev/input/event6: EV_SYN SYN_REPORT 00000000
/dev/input/event6: EV_ABS ABS_MT_TRACKING_ID 00000001
/dev/input/event6: EV_KEY BTN_TOUCH DOWN
/dev/input/event6: EV_SYN SYN_REPORT 00000000
/dev/input/event6: EV_ABS ABS_MT_TRACKING_ID ffffffff
/dev/input/event6: EV_KEY BTN_TOUCH UP
/dev/input/event6: EV_SYN SYN_REPORT 00000000
On 4.14
add device 2: /dev/input/event5
name: "BLE-M1 UNKNOWN"
/dev/input/event5: EV_MSC MSC_SCAN 000d0042
/dev/input/event5: EV_KEY BTN_TOUCH DOWN
/dev/input/event5: EV_KEY BTN_DIGI DOWN
/dev/input/event5: EV_ABS ABS_MISC 00000001
/dev/input/event5: EV_ABS ABS_X 00000800
/dev/input/event5: EV_ABS ABS_Y 00000d60
/dev/input/event5: EV_ABS 0029 00000001
/dev/input/event5: EV_SYN SYN_REPORT 00000000
/dev/input/event5: EV_MSC MSC_SCAN 000d0042
/dev/input/event5: EV_KEY BTN_TOUCH UP
/dev/input/event5: EV_KEY BTN_DIGI UP
/dev/input/event5: EV_ABS 0029 00000000
/dev/input/event5: EV_SYN SYN_REPORT 00000000
/dev/input/event5: EV_MSC MSC_SCAN 000d0042
/dev/input/event5: EV_KEY BTN_TOUCH DOWN
/dev/input/event5: EV_KEY BTN_DIGI DOWN
/dev/input/event5: EV_ABS 0029 00000001
/dev/input/event5: EV_SYN SYN_REPORT 00000000
/dev/input/event5: EV_MSC MSC_SCAN 000d0042
/dev/input/event5: EV_KEY BTN_TOUCH UP
/dev/input/event5: EV_KEY BTN_DIGI UP
/dev/input/event5: EV_ABS 0029 00000000
/dev/input/event5: EV_SYN SYN_REPORT 00000000
As I have little understanding of the framework, use cases and of the
flow, I am sorry, if the information provided above is
incomplete (w.r.t. what you were expecting).
Thanks
Neeraj
Cheers,
Benjamin
Thanks
Neeraj
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QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, hosted by The Linux Foundation
