Re: [PATCH 2/5] soundwire: sysfs: cleanup the logic for creating the dp0 sysfs attributes

[Pierre-Louis Bossart]

On 7/29/22 08:50, Greg Kroah-Hartman wrote:
> There's no need to special-case the dp0 sysfs attributes, the
> is_visible() callback in the attribute group can handle that for us, so
> add that and add it to the attribute group list making the logic simpler
> overall.
> 
> This is a step on the way to moving all of the sysfs attribute handling
> into the default driver core attribute group logic so that the soundwire
> core does not have to do any of it manually.
> 
> Cc: Vinod Koul <vkoul@xxxxxxxxxx>
> Cc: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
> Cc: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
> Cc: Sanyog Kale <sanyog.r.kale@xxxxxxxxx>
> Cc: alsa-devel@xxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/soundwire/sysfs_slave.c | 18 ++++++++++++------
>  1 file changed, 12 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/soundwire/sysfs_slave.c b/drivers/soundwire/sysfs_slave.c
> index 83e3f6cc3250..3723333a5c2b 100644
> --- a/drivers/soundwire/sysfs_slave.c
> +++ b/drivers/soundwire/sysfs_slave.c
> @@ -174,6 +174,16 @@ static ssize_t words_show(struct device *dev,
>  }
>  static DEVICE_ATTR_RO(words);
>  
> +static umode_t dp0_is_visible(struct kobject *kobj, struct attribute *attr,
> +			      int n)
> +{
> +	struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj));
> +
> +	if (slave->prop.dp0_prop)
> +		return attr->mode;
> +	return 0;
> +}

This changes the results slightly by creating an empty 'dp0' directory
with no attributes inside.

Before:

[root@fedora ~]# cd /sys/bus/soundwire/devices/sdw:3:025d:0714:01
[root@fedora sdw:3:025d:0714:01]# ls dp0
ls: cannot access 'dp0': No such file or directory

After:
[root@fedora sdw:3:025d:0714:01]# ls dp0

> +
>  static struct attribute *dp0_attrs[] = {
>  	&dev_attr_max_word.attr,
>  	&dev_attr_min_word.attr,
> @@ -190,12 +200,14 @@ static struct attribute *dp0_attrs[] = {
>   */
>  static const struct attribute_group dp0_group = {
>  	.attrs = dp0_attrs,
> +	.is_visible = dp0_is_visible,
>  	.name = "dp0",
>  };
>  
>  static const struct attribute_group *slave_groups[] = {
>  	&slave_attr_group,
>  	&sdw_slave_dev_attr_group,
> +	&dp0_group,
>  	NULL,
>  };
>  
> @@ -207,12 +219,6 @@ int sdw_slave_sysfs_init(struct sdw_slave *slave)
>  	if (ret < 0)
>  		return ret;
>  
> -	if (slave->prop.dp0_prop) {
> -		ret = devm_device_add_group(&slave->dev, &dp0_group);
> -		if (ret < 0)
> -			return ret;
> -	}
> -
>  	if (slave->prop.source_ports || slave->prop.sink_ports) {
>  		ret = sdw_slave_sysfs_dpn_init(slave);
>  		if (ret < 0)