Re: [PATCH] iio: light: hid-sensor-als: Avoid failure for chromaticity support

[Jonathan Cameron <jic23@kernel.org>]

On Fri, 15 Dec 2023 08:01:59 -0800
Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> wrote:

> With the commit ee3710f39f9d ("iio: hid-sensor-als: Add light chromaticity
> support"), there is an assumption that the every HID ALS descriptor has
> support of usage ids for chromaticity support. If they are not present,
> probe fails for the driver . This breaks ALS functionality on majority of
> platforms.
> 
> It is possible that chromaticity usage ids are not present. When not
> present, restrict number of IIO channels to not include support for
> chromaticity and continue.
> 
> Fixes: ee3710f39f9d ("iio: hid-sensor-als: Add light chromaticity support")
> Reported-by: Thomas Weißschuh <thomas@t-8ch.de>
> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=218223
> Signed-off-by: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com>
> Cc: stable@vger.kernel.org
> ---
>  drivers/iio/light/hid-sensor-als.c | 24 ++++++++++++++++--------
>  1 file changed, 16 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/iio/light/hid-sensor-als.c b/drivers/iio/light/hid-sensor-als.c
> index f17304b54468..9941b0b927c7 100644
> --- a/drivers/iio/light/hid-sensor-als.c
> +++ b/drivers/iio/light/hid-sensor-als.c
> @@ -303,11 +303,14 @@ 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)
> +				struct als_state *st,
> +				int *max_channels)
>  {
>  	int ret;
>  	int i;
>  
> +	*max_channels = CHANNEL_SCAN_INDEX_MAX;
> +
>  	for (i = 0; i <= CHANNEL_SCAN_INDEX_ILLUM; ++i) {
>  		ret = sensor_hub_input_get_attribute_info(hsdev,
>  						HID_INPUT_REPORT,
> @@ -326,8 +329,12 @@ static int als_parse_report(struct platform_device *pdev,
>  				usage_id,
>  				HID_USAGE_SENSOR_LIGHT_COLOR_TEMPERATURE,
>  				&st->als[CHANNEL_SCAN_INDEX_COLOR_TEMP]);
> -	if (ret < 0)
> -		return ret;
> +	if (ret < 0) {
> +		*max_channels = CHANNEL_SCAN_INDEX_ILLUM;
> +		ret = 0;
> +		goto skip_color_chromaticity;
> +	}
> +
>  	als_adjust_channel_bit_mask(channels, CHANNEL_SCAN_INDEX_COLOR_TEMP,
>  				st->als[CHANNEL_SCAN_INDEX_COLOR_TEMP].size);
>  
> @@ -354,6 +361,7 @@ static int als_parse_report(struct platform_device *pdev,
>  			st->als[next_scan_index].report_id);
>  	}
>  
> +skip_color_chromaticity:
>  	st->scale_precision = hid_sensor_format_scale(usage_id,
>  				&st->als[CHANNEL_SCAN_INDEX_INTENSITY],
>  				&st->scale_pre_decml, &st->scale_post_decml);
> @@ -364,7 +372,7 @@ static int als_parse_report(struct platform_device *pdev,
>  /* Function to initialize the processing for usage id */
>  static int hid_als_probe(struct platform_device *pdev)
>  {
> -	int ret = 0;
> +	int ret = 0, max_channels;
>  	static const char *name = "als";
>  	struct iio_dev *indio_dev;
>  	struct als_state *als_state;
> @@ -398,15 +406,15 @@ static int hid_als_probe(struct platform_device *pdev)
>  
>  	ret = als_parse_report(pdev, hsdev,
>  			       (struct iio_chan_spec *)indio_dev->channels,
> -			       hsdev->usage,
> -			       als_state);
> +			       hsdev->usage, als_state, &max_channels);
>  	if (ret) {
>  		dev_err(&pdev->dev, "failed to setup attributes\n");
>  		return ret;
>  	}
>  
> -	indio_dev->num_channels =
> -				ARRAY_SIZE(als_channels);
> +	/* +1 to include time stamp */
> +	indio_dev->num_channels = max_channels + 1;

In the current array the timestamp channel isn't the next one, so how does this work?

I think we either have to form the channel array dynamically or pick between
one that does have the colour info and one that doesn't for the original case.

Given timing we may just need to revert the broken patch and revisit this next
cycle.

Jonathan


> +
>  	indio_dev->info = &als_info;
>  	indio_dev->name = name;
>  	indio_dev->modes = INDIO_DIRECT_MODE;