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

[Jonathan Cameron <Jonathan.Cameron@Huawei.com>]

On Tue, 29 Oct 2024 13:20:06 +0100
Ricardo Ribalda <ribalda@chromium.org> wrote:

> 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.
Same was true (0 or 1) for the activity classification but I'm not
keen on certainty :)  So lets' copy that precedence and *100


> 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;
> > >  
> >  
> 
>