Re: [PATCH 2/8] iio: hid-sensor-als: Add light color temperature support

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

On Sun, 17 Sep 2023 20:13:46 +0530
Basavaraj Natikar <bnatikar@amd.com> wrote:

> On 9/17/2023 4:30 PM, Jonathan Cameron wrote:
> > On Fri, 15 Sep 2023 10:46:57 +0530
> > Basavaraj Natikar <Basavaraj.Natikar@amd.com> wrote:
> >  
> >> In most cases, ambient color sensors also support light color temperature.
> >> As a result, add support of light color temperature.
> >>
> >> Signed-off-by: Basavaraj Natikar <Basavaraj.Natikar@amd.com>
> >> ---
> >>  drivers/iio/light/hid-sensor-als.c | 33 ++++++++++++++++++++++++++++++
> >>  include/linux/hid-sensor-ids.h     |  1 +
> >>  2 files changed, 34 insertions(+)
> >>
> >> diff --git a/drivers/iio/light/hid-sensor-als.c b/drivers/iio/light/hid-sensor-als.c
> >> index 48879e233aec..220fb93fea6d 100644
> >> --- a/drivers/iio/light/hid-sensor-als.c
> >> +++ b/drivers/iio/light/hid-sensor-als.c
> >> @@ -16,6 +16,7 @@
> >>  enum {
> >>  	CHANNEL_SCAN_INDEX_INTENSITY = 0,
> >>  	CHANNEL_SCAN_INDEX_ILLUM = 1,  
> > Either drop, the = 1 or keep consistency for TEMP. 
> > I don't think the = 1 is useful so I'd drop it.
> >  
> >> +	CHANNEL_SCAN_INDEX_COLOR_TEMP,
> >>  	CHANNEL_SCAN_INDEX_MAX
> >>  };
> >>  
> >> @@ -65,6 +66,18 @@ static const struct iio_chan_spec als_channels[] = {
> >>  		BIT(IIO_CHAN_INFO_HYSTERESIS_RELATIVE),
> >>  		.scan_index = CHANNEL_SCAN_INDEX_ILLUM,
> >>  	},
> >> +	{
> >> +		.type = IIO_TEMP,  
> > Using a temperature channel for color temp is a bit of a stretch,
> > Particularly as it's likely we will see light sensors with actual
> > air temperature sensors in them at somepoint even if we don't have
> > any already.
> >
> > So this needs a new channel type
> > IIO_COLORTEMP or similar.
> >
> > Units for this probably want to be kelvin unlike the mili decrees centigrade
> > used for IIO_TEMP.
> >  
> >> +		.modified = 1,
> >> +		.channel2 = IIO_MOD_TEMP_AMBIENT,  
> > I don't really see the modifier as useful here. That exists for thermocouple
> > type systems where it is necessary to know ambient vs sample temperatures.  
> 
> Sure Jonathan, I will address all comments in this series in v2.
> Also, can i add new channel type IIO_COLORTEMP with following channel index
> for light color temperature ?

Looks good.

Jonathan

>        {
>                 .type = IIO_COLORTEMP,
>                 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
>                 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
>                         BIT(IIO_CHAN_INFO_SCALE) |
>                         BIT(IIO_CHAN_INFO_SAMP_FREQ) |
>                         BIT(IIO_CHAN_INFO_HYSTERESIS) |
>                         BIT(IIO_CHAN_INFO_HYSTERESIS_RELATIVE),
>                 .scan_index = CHANNEL_SCAN_INDEX_COLOR_TEMP,
>         }
> 
> Thanks,
> --
> Basavaraj
> 
> >
> >  
> >> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
> >> +		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_OFFSET) |
> >> +			BIT(IIO_CHAN_INFO_SCALE) |
> >> +			BIT(IIO_CHAN_INFO_SAMP_FREQ) |
> >> +			BIT(IIO_CHAN_INFO_HYSTERESIS) |
> >> +			BIT(IIO_CHAN_INFO_HYSTERESIS_RELATIVE),
> >> +		.scan_index = CHANNEL_SCAN_INDEX_COLOR_TEMP,
> >> +	},
> >>  	IIO_CHAN_SOFT_TIMESTAMP(CHANNEL_SCAN_INDEX_TIMESTAMP)
> >>  };
> >>  
> >> @@ -103,6 +116,11 @@ static int als_read_raw(struct iio_dev *indio_dev,
> >>  			min = als_state->als_illum[chan->scan_index].logical_minimum;
> >>  			address = HID_USAGE_SENSOR_LIGHT_ILLUM;
> >>  			break;
> >> +		case  CHANNEL_SCAN_INDEX_COLOR_TEMP:
> >> +			report_id = als_state->als_illum[chan->scan_index].report_id;
> >> +			min = als_state->als_illum[chan->scan_index].logical_minimum;
> >> +			address = HID_USAGE_SENSOR_LIGHT_COLOR_TEMPERATURE;
> >> +			break;
> >>  		default:
> >>  			report_id = -1;
> >>  			break;
> >> @@ -223,6 +241,10 @@ static int als_capture_sample(struct hid_sensor_hub_device *hsdev,
> >>  		als_state->scan.illum[CHANNEL_SCAN_INDEX_ILLUM] = sample_data;
> >>  		ret = 0;
> >>  		break;
> >> +	case HID_USAGE_SENSOR_LIGHT_COLOR_TEMPERATURE:
> >> +		als_state->scan.illum[CHANNEL_SCAN_INDEX_COLOR_TEMP] = sample_data;
> >> +		ret = 0;
> >> +		break;
> >>  	case HID_USAGE_SENSOR_TIME_TIMESTAMP:
> >>  		als_state->timestamp = hid_sensor_convert_timestamp(&als_state->common_attributes,
> >>  								    *(s64 *)raw_data);
> >> @@ -256,6 +278,17 @@ static int als_parse_report(struct platform_device *pdev,
> >>  			st->als_illum[i].report_id);
> >>  	}
> >>  
> >> +	ret = sensor_hub_input_get_attribute_info(hsdev, HID_INPUT_REPORT, usage_id,
> >> +						  HID_USAGE_SENSOR_LIGHT_COLOR_TEMPERATURE,
> >> +						  &st->als_illum[CHANNEL_SCAN_INDEX_COLOR_TEMP]);
> >> +	if (ret < 0)
> >> +		return ret;
> >> +	als_adjust_channel_bit_mask(channels, CHANNEL_SCAN_INDEX_COLOR_TEMP,
> >> +				    st->als_illum[CHANNEL_SCAN_INDEX_COLOR_TEMP].size);
> >> +
> >> +	dev_dbg(&pdev->dev, "als %x:%x\n", st->als_illum[CHANNEL_SCAN_INDEX_COLOR_TEMP].index,
> >> +		st->als_illum[CHANNEL_SCAN_INDEX_COLOR_TEMP].report_id);
> >> +
> >>  	st->scale_precision = hid_sensor_format_scale(usage_id,
> >>  						      &st->als_illum[CHANNEL_SCAN_INDEX_INTENSITY],
> >>  						      &st->scale_pre_decml, &st->scale_post_decml);
> >> diff --git a/include/linux/hid-sensor-ids.h b/include/linux/hid-sensor-ids.h
> >> index 13b1e65fbdcc..8af4fb3e0254 100644
> >> --- a/include/linux/hid-sensor-ids.h
> >> +++ b/include/linux/hid-sensor-ids.h
> >> @@ -21,6 +21,7 @@
> >>  #define HID_USAGE_SENSOR_ALS					0x200041
> >>  #define HID_USAGE_SENSOR_DATA_LIGHT				0x2004d0
> >>  #define HID_USAGE_SENSOR_LIGHT_ILLUM				0x2004d1
> >> +#define HID_USAGE_SENSOR_LIGHT_COLOR_TEMPERATURE		0x2004d2
> >>  
> >>  /* PROX (200011) */
> >>  #define HID_USAGE_SENSOR_PROX                                   0x200011  
>