Hi Rong,
On Tue, Jun 02, 2026 at 01:25:57AM +0800, Rong Zhang wrote:
>
> Hi all,
>
> Hopefully I'm not too late to show up here.
>
> > From: Peter Hutterer <[email protected]>
> >
> > A Digitizer/Button Type value of 1 indicates the device is a
> > pressurepad, see
> > https://learn.microsoft.com/en-us/windows-hardware/design/component-guidelines/touchpad-windows-precision-touchpad-collection#device-capabilities-feature-report
> >
> > Signed-off-by: Peter Hutterer <[email protected]>
> > ---
> > drivers/hid/hid-multitouch.c | 12 +++++++++++-
> > 1 file changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/hid/hid-multitouch.c b/drivers/hid/hid-multitouch.c
> > index
> > 179dc316b4b518d78bdc900d9fd15756c5eba83e..382e6f50c4f7e663af7d028abb8be7cb2e6e7b8e
> > 100644
> > --- a/drivers/hid/hid-multitouch.c
> > +++ b/drivers/hid/hid-multitouch.c
> > @@ -81,6 +81,7 @@ MODULE_LICENSE("GPL");
> > #define MT_INPUTMODE_TOUCHPAD 0x03
> >
> > #define MT_BUTTONTYPE_CLICKPAD 0
> > +#define MT_BUTTONTYPE_PRESSUREPAD 1
> >
> > enum latency_mode {
> > HID_LATENCY_NORMAL = 0,
> > @@ -179,6 +180,7 @@ struct mt_device {
> > __u8 inputmode_value; /* InputMode HID feature value */
> > __u8 maxcontacts;
> > bool is_buttonpad; /* is this device a button pad? */
> > + bool is_pressurepad; /* is this device a pressurepad? */
> > bool is_haptic_touchpad; /* is this device a haptic touchpad? */
> > bool serial_maybe; /* need to check for serial protocol */
> >
> > @@ -530,8 +532,14 @@ static void mt_feature_mapping(struct hid_device *hdev,
> > }
> >
> > mt_get_feature(hdev, field->report);
> > - if (field->value[usage->usage_index] == MT_BUTTONTYPE_CLICKPAD)
> > + switch (field->value[usage->usage_index]) {
> > + case MT_BUTTONTYPE_CLICKPAD:
> > td->is_buttonpad = true;
> > + break;
> > + case MT_BUTTONTYPE_PRESSUREPAD:
> > + td->is_pressurepad = true;
> > + break;
> > + }
> >
> > break;
> > case 0xff0000c5:
> > @@ -1393,6 +1401,8 @@ static int mt_touch_input_configured(struct
> > hid_device *hdev,
> >
> > if (td->is_buttonpad)
> > __set_bit(INPUT_PROP_BUTTONPAD, input->propbit);
> > + if (td->is_pressurepad)
> > + __set_bit(INPUT_PROP_PRESSUREPAD, input->propbit);
>
> I noticed that this leads to dual reporting on my device.
>
> Consider previous checks:
>
> if (application == HID_DG_TOUCHPAD) {
> mt_application->mt_flags |= INPUT_MT_POINTER;
> td->inputmode_value = MT_INPUTMODE_TOUCHPAD;
> }
>
> ...
>
> /* check for clickpads */
> if ((app->mt_flags & INPUT_MT_POINTER) &&
> (app->buttons_count == 1))
> td->is_buttonpad = true;
>
> ... where `td->is_buttonpad' is set to true when a pressure pad has only
> one button, i.e., the "touchpad button integrated with digitizer" [1].
> Most (if not all) pressure pads fall into this category. As a result,
> the presence of INPUT_PROP_PRESSUREPAD is always accompanied by the
> presence of INPUT_PROP_BUTTONPAD.
Yes, this is intended, see commit
ae8966b7b5bd69b86209cc34bcca1ba9f18b68e6 which lists this in the commit
message:
```
This means:
- clickpad: INPUT_PROP_BUTTONPAD
- pressurepad: INPUT_PROP_BUTTONPAD + INPUT_PROP_PRESSUREPAD
- pressurepad with configurable haptics:
INPUT_PROP_BUTTONPAD + INPUT_PROP_PRESSUREPAD + FF_HAPTIC
```
We have to keep setting BUTTONPAD on all pressurepads because otherwise
we'd break existing userspace which relies on this.
Cheers,
Peter
