Re: [PATCH v4 1/4] iio: hid-sensor-als: Assign channels dynamically

[Jonathan Cameron <jic23@kernel.org>]

On Sun,  4 Feb 2024 05:03:29 -0800
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> wrote:

> Instead of assuming that every channel defined statically by
> als_channels[] is present, assign dynamically based on presence of the
> respective usage id in the descriptor. This will allow to register ALS
> with limited channel support. Append the timestamp as the last channel.
> 
> Update available_scan_mask to specify all channels which are present.
> 
> There is no intentional function changes done.
> 
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
Hi Srinivas,

Logic looks fine, but not that global variable...

> ---
> v4:
> Addressed comments from Jonthan:
> 	- Use available_scan_masks
> 	- timestamp location is fixed and left gaps in sample data for absent channels
> 	- Use CHANNEL_SCAN_INDEX_MAX as limit to check presence of usage ids, otherwise
> 	  it will miss newer channels added in subsequent patches.
> v3:
> Addressed comments from Jonthan:
> 	- Remove channel allocation and move to iio_priv()
> 	- Parse all usage IDs in a single loop and continue
> 	for failure. This way the temperature and chromaticity
> 	will not need any special processing to parse usage ids.
> 	- Don't leave empty channel indexes
> 
> v2:
> New change
> 
>  drivers/iio/light/hid-sensor-als.c | 52 +++++++++++++++++++++---------
>  1 file changed, 36 insertions(+), 16 deletions(-)
> 
> diff --git a/drivers/iio/light/hid-sensor-als.c b/drivers/iio/light/hid-sensor-als.c
> index b6c4bef2a7bb..d3b892c0e307 100644
> --- a/drivers/iio/light/hid-sensor-als.c
> +++ b/drivers/iio/light/hid-sensor-als.c
> @@ -25,6 +25,7 @@ struct als_state {
>  	struct hid_sensor_hub_callbacks callbacks;
>  	struct hid_sensor_common common_attributes;
>  	struct hid_sensor_hub_attribute_info als[CHANNEL_SCAN_INDEX_MAX];
> +	struct iio_chan_spec channels[CHANNEL_SCAN_INDEX_MAX + 1];
>  	struct {
>  		u32 illum[CHANNEL_SCAN_INDEX_MAX];
>  		u64 timestamp __aligned(8);
> @@ -33,9 +34,16 @@ struct als_state {
>  	int scale_post_decml;
>  	int scale_precision;
>  	int value_offset;
> +	int num_channels;
>  	s64 timestamp;
>  };
>  
> +/* The order of usage ids must match scan index starting from CHANNEL_SCAN_INDEX_INTENSITY */
> +static const u32 als_usage_ids[] = {
> +	HID_USAGE_SENSOR_LIGHT_ILLUM,
> +	HID_USAGE_SENSOR_LIGHT_ILLUM,
> +};
> +
>  static const u32 als_sensitivity_addresses[] = {
>  	HID_USAGE_SENSOR_DATA_LIGHT,
>  	HID_USAGE_SENSOR_LIGHT_ILLUM,
> @@ -68,6 +76,8 @@ static const struct iio_chan_spec als_channels[] = {
>  	IIO_CHAN_SOFT_TIMESTAMP(CHANNEL_SCAN_INDEX_TIMESTAMP)
>  };
>  
> +static unsigned long als_scan_mask[] = {0, 0};

Global? No. Could be multiple instances with different sensors supported.
Needs to be embedded in the als_state structure so it is per instance.

> +
>  /* Adjust channel real bits based on report descriptor */
>  static void als_adjust_channel_bit_mask(struct iio_chan_spec *channels,
>  					int channel, int size)
> @@ -238,27 +248,38 @@ static int als_capture_sample(struct hid_sensor_hub_device *hsdev,
>  /* Parse report which is specific to an usage id*/
>  static int als_parse_report(struct platform_device *pdev,
>  				struct hid_sensor_hub_device *hsdev,
> -				struct iio_chan_spec *channels,
>  				unsigned usage_id,
>  				struct als_state *st)
>  {
> -	int ret;
> +	struct iio_chan_spec *channels;
> +	int ret, index = 0;
>  	int i;
>  
> -	for (i = 0; i <= CHANNEL_SCAN_INDEX_ILLUM; ++i) {
> +	channels = st->channels;
> +
> +	for (i = 0; i < CHANNEL_SCAN_INDEX_MAX; ++i) {
>  		ret = sensor_hub_input_get_attribute_info(hsdev,
>  						HID_INPUT_REPORT,
>  						usage_id,
> -						HID_USAGE_SENSOR_LIGHT_ILLUM,
> +						als_usage_ids[i],
>  						&st->als[i]);
>  		if (ret < 0)
> -			return ret;
> -		als_adjust_channel_bit_mask(channels, i, st->als[i].size);
> +			continue;
> +
> +		channels[index] = als_channels[i];
> +		als_scan_mask[0] |= BIT(i);
> +		als_adjust_channel_bit_mask(channels, index, st->als[i].size);
> +		++index;
>  
>  		dev_dbg(&pdev->dev, "als %x:%x\n", st->als[i].index,
>  			st->als[i].report_id);
>  	}
>  
> +	st->num_channels = index;
> +	/* Return success even if one usage id is present */
> +	if (index)
> +		ret = 0;
> +
>  	st->scale_precision = hid_sensor_format_scale(usage_id,
>  				&st->als[CHANNEL_SCAN_INDEX_INTENSITY],
>  				&st->scale_pre_decml, &st->scale_post_decml);
> @@ -294,15 +315,7 @@ static int hid_als_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> -	indio_dev->channels = devm_kmemdup(&pdev->dev, als_channels,
> -					   sizeof(als_channels), GFP_KERNEL);
> -	if (!indio_dev->channels) {
> -		dev_err(&pdev->dev, "failed to duplicate channels\n");
> -		return -ENOMEM;
> -	}
> -
>  	ret = als_parse_report(pdev, hsdev,
> -			       (struct iio_chan_spec *)indio_dev->channels,
>  			       hsdev->usage,
>  			       als_state);
>  	if (ret) {
> @@ -310,8 +323,15 @@ static int hid_als_probe(struct platform_device *pdev)
>  		return ret;
>  	}
>  
> -	indio_dev->num_channels =
> -				ARRAY_SIZE(als_channels);
> +	/* Add timestamp channel */
> +	als_state->channels[als_state->num_channels] = als_channels[CHANNEL_SCAN_INDEX_TIMESTAMP];
> +
> +	/* +1 for adding timestamp channel */
> +	indio_dev->num_channels = als_state->num_channels + 1;
> +
> +	indio_dev->channels = als_state->channels;
> +	indio_dev->available_scan_masks = als_scan_mask;
> +
>  	indio_dev->info = &als_info;
>  	indio_dev->name = name;
>  	indio_dev->modes = INDIO_DIRECT_MODE;