Re: [PATCH v2 3/5] iio: Add channel type for attention

[Ricardo Ribalda <ribalda@chromium.org>]

Hi Jonathan

On Mon, 28 Oct 2024 at 21:34, Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Mon, 28 Oct 2024 10:12:23 +0000
> Ricardo Ribalda <ribalda@chromium.org> wrote:
>
> > Add a new channel type representing if the user's attention state to the
> > the system. This usually means if the user is looking at the screen or
> > not.
> >
> > Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
> > ---
> >  Documentation/ABI/testing/sysfs-bus-iio | 7 +++++++
> >  drivers/iio/industrialio-core.c         | 1 +
> >  include/uapi/linux/iio/types.h          | 1 +
> >  tools/iio/iio_event_monitor.c           | 2 ++
> >  4 files changed, 11 insertions(+)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-bus-iio b/Documentation/ABI/testing/sysfs-bus-iio
> > index 89943c2d54e8..d5a2f93bd051 100644
> > --- a/Documentation/ABI/testing/sysfs-bus-iio
> > +++ b/Documentation/ABI/testing/sysfs-bus-iio
> > @@ -2339,3 +2339,10 @@ KernelVersion: 6.10
> >  Contact:     linux-iio@vger.kernel.org
> >  Description:
> >               The value of current sense resistor in Ohms.
> > +
> > +What:                /sys/.../iio:deviceX/in_attention_raw
> > +KernelVersion:       6.13
> > +Contact:     linux-iio@vger.kernel.org
> > +Description:
> > +             Boolean value representing the user's attention to the system.
> > +             This usually means if the user is looking at the screen or not.
>
> Hmm. I should have thought of this when I replied to suggest a new channel type.
> The question is 'units' for a decision.
>
> Last time we hit something like this where processing is used to make a decision
> we decided to at least allow for the concept of 'certainty'.
>
> The idea being that smarter sensors would tell us something about how sure they
> are that the attention is on the device.
> The analogy being with activity detection. See in_activity_walking_input
> in Documentation/ABI/testing/sysfs-bus-iio
>
> Do you think that would be appropriate here as well?  For this device
> it would take the values 0 and 100 rather than 0 and 1.

For the particular device that I want to support, they are giving me a
value of 1 and 0, and the example from usb.org seems to work the same
way (Logical Maximum of 1)
https://www.usb.org/sites/default/files/hutrr107-humanpresenceattention_1.pdf

I have no problem multiplying my value by 100 if you think there will
be a use case for that. It will not have a major performance impact on
the driver.

You decide ;)

>
>
> > diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c
> > index 6a6568d4a2cb..bdfb51275b68 100644
> > --- a/drivers/iio/industrialio-core.c
> > +++ b/drivers/iio/industrialio-core.c
> > @@ -95,6 +95,7 @@ static const char * const iio_chan_type_name_spec[] = {
> >       [IIO_DELTA_VELOCITY] = "deltavelocity",
> >       [IIO_COLORTEMP] = "colortemp",
> >       [IIO_CHROMATICITY] = "chromaticity",
> > +     [IIO_ATTENTION] = "attention",
> >  };
> >
> >  static const char * const iio_modifier_names[] = {
> > diff --git a/include/uapi/linux/iio/types.h b/include/uapi/linux/iio/types.h
> > index f2e0b2d50e6b..12886d4465e4 100644
> > --- a/include/uapi/linux/iio/types.h
> > +++ b/include/uapi/linux/iio/types.h
> > @@ -51,6 +51,7 @@ enum iio_chan_type {
> >       IIO_DELTA_VELOCITY,
> >       IIO_COLORTEMP,
> >       IIO_CHROMATICITY,
> > +     IIO_ATTENTION,
> >  };
> >
> >  enum iio_modifier {
> > diff --git a/tools/iio/iio_event_monitor.c b/tools/iio/iio_event_monitor.c
> > index 8073c9e4fe46..ed9a677f1028 100644
> > --- a/tools/iio/iio_event_monitor.c
> > +++ b/tools/iio/iio_event_monitor.c
> > @@ -63,6 +63,7 @@ static const char * const iio_chan_type_name_spec[] = {
> >       [IIO_DELTA_VELOCITY] = "deltavelocity",
> >       [IIO_COLORTEMP] = "colortemp",
> >       [IIO_CHROMATICITY] = "chromaticity",
> > +     [IIO_ATTENTION] = "attention",
> >  };
> >
> >  static const char * const iio_ev_type_text[] = {
> > @@ -183,6 +184,7 @@ static bool event_is_known(struct iio_event_data *event)
> >       case IIO_DELTA_VELOCITY:
> >       case IIO_COLORTEMP:
> >       case IIO_CHROMATICITY:
> > +     case IIO_ATTENTION:
> >               break;
> >       default:
> >               return false;
> >
>


-- 
Ricardo Ribalda