On Sun, 2021-01-24 at 13:14 +0000, Jonathan Cameron wrote:
> On Wed, 20 Jan 2021 15:47:05 +0800
> Ye Xiang <xiang...@intel.com> wrote:
>
> > Some hid sensors may use relative sensitivity such as als sensor.
> > This patch add relative sensitivity check for all hid-sensors.
> >
> > Signed-off-by: Ye Xiang <xiang...@intel.com>
> > ---
> > .../iio/common/hid-sensors/hid-sensor-attributes.c | 11
> > ++++++++++-
> > include/linux/hid-sensor-ids.h | 1 +
> > 2 files changed, 11 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> > b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> > index d349ace2e33f..b685c292a179 100644
> > --- a/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> > +++ b/drivers/iio/common/hid-sensors/hid-sensor-attributes.c
> > @@ -480,7 +480,7 @@ int hid_sensor_parse_common_attributes(struct
> > hid_sensor_hub_device *hsdev,
> >
> > /*
> > * Set Sensitivity field ids, when there is no individual
> > modifier, will
> > - * check absolute sensitivity of data field
> > + * check absolute sensitivity and relative sensitivity of data
> > field
> > */
> > for (i = 0; i < sensitivity_addresses_len && st-
> > >sensitivity.index < 0; i++) {
> > sensor_hub_input_get_attribute_info(hsdev,
> > @@ -488,6 +488,15 @@ int hid_sensor_parse_common_attributes(struct
> > hid_sensor_hub_device *hsdev,
> > HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSIT
> > IVITY_ABS |
> > sensitivity_addresses[i],
> > &st->sensitivity);
> > +
> > + if (st->sensitivity.index >= 0)
> > + break;
> > +
> > + sensor_hub_input_get_attribute_info(hsdev,
> > + HID_FEATURE_REPORT, usage_id,
> > + HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSIT
> > IVITY_REL_PCT |
> > + sensitivity_addresses[i],
> > + &st->sensitivity);
>
> We can't provide the value to userspace without reflecting the
> difference between
> the two ways of expressing it.
>
> It seems there are 3 ways sensitivity is expressed.
> 1. Raw value in same units as the measurement (easy one and what is
> currently reported)
> 2. Percentage of range - also relatively easy to transform into the
> same as 1.
> 3. Percentage of prior reading.. This one doesn't fit in any
> existing ABI, so
> unfortunately we'll have to invent something new along the lines
> of
> *_hysteresis_relative
This is why it was not added before when I developed. But later few
years back there was a patch to add this by one of our developer. There
was some discussion, I thought it was decided it is OK to add.
But I agree, we should add new ABI as you suggested. Now almost every
laptop has HID sensors, better to address this.
Thanks,
Srinivas
> Jonathan
>
>
>
> > }
> >
> > st->raw_hystersis = -1;
> > diff --git a/include/linux/hid-sensor-ids.h b/include/linux/hid-
> > sensor-ids.h
> > index 3bbdbccc5805..ac631159403a 100644
> > --- a/include/linux/hid-sensor-ids.h
> > +++ b/include/linux/hid-sensor-ids.h
> > @@ -149,6 +149,7 @@
> > /* Per data field properties */
> > #define HID_USAGE_SENSOR_DATA_MOD_NONE
> > 0x00
> > #define HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSITIVITY_ABS
> > 0x1000
> > +#define
> > HID_USAGE_SENSOR_DATA_MOD_CHANGE_SENSITIVITY_REL_PCT 0xE
> > 000
> >
> > /* Power state enumerations */
> > #define HID_USAGE_SENSOR_PROP_POWER_STATE_UNDEFINED_ENUM 0x20085
> > 0
