Re: [RFC PATCH v2 1/5] iio: core: Point users of extend_name field to read_label callback

[Jonathan Cameron]

On Mon, 16 Jan 2023 23:09:05 +0100
Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx> wrote:

> As mentioned and discussed in [1] extend_name should not be used for
> full channel labels (and most drivers seem to only use it to express a
> short type of a channel) as this affects sysfs filenames, while the
> label name is supposed to be extracted from the *_label sysfs file
> instead.  This appears to have been unclear to some drivers as
> extend_name is also used when read_label is unset, achieving an initial
> goal of providing sensible names in *_label sysfs files without noticing
> that sysfs filenames are (negatively and likely unintentionally)
> affected as well.
> 
> Point readers of iio_chan_spec::extend_name to iio_info::read_label by
> mentioning deprecation and side-effects of this field.
> 
> [1]: https://lore.kernel.org/linux-arm-msm/20221221223432.si2aasbleiicayfl@xxxxxxxxxxxxxx/
> 
> Suggested-by: Jonathan Cameron <jic23@xxxxxxxxxx>
> Signed-off-by: Marijn Suijten <marijn.suijten@xxxxxxxxxxxxxx>
> ---
>  include/linux/iio/iio.h | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/include/linux/iio/iio.h b/include/linux/iio/iio.h
> index 81413cd3a3e7..36c89f238fb9 100644
> --- a/include/linux/iio/iio.h
> +++ b/include/linux/iio/iio.h
> @@ -221,6 +221,9 @@ struct iio_event_spec {
>   * @extend_name:	Allows labeling of channel attributes with an
>   *			informative name. Note this has no effect codes etc,
>   *			unlike modifiers.
> + *			This field is deprecated in favour of overriding read_label
> + *			in iio_info, which unlike @extend_name does not affect sysfs
> + *			filenames.
Perhaps reword as

This field is deprecated in favour of overriding the default label
by providing a read_label() callback in iio_info, which unlike
@extend_name does not affect sysfs filenames.
?
>   * @datasheet_name:	A name used in in-kernel mapping of channels. It should
>   *			correspond to the first name that the channel is referred
>   *			to by in the datasheet (e.g. IND), or the nearest