Re: [PATCH 3/6] soundwire: sysfs: cleanup the logic for creating the dp0 sysfs attributes

[Dan Williams <dan.j.williams@intel.com>]

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@kernel.org>
> Cc: Bard Liao <yung-chuan.liao@linux.intel.com>
> Cc: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
> Cc: Sanyog Kale <sanyog.r.kale@intel.com>
> Cc: alsa-devel@alsa-project.org
> Cc: linux-kernel@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  drivers/soundwire/sysfs_slave.c | 28 ++++++++++++++++++++++------
>  1 file changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/soundwire/sysfs_slave.c b/drivers/soundwire/sysfs_slave.c
> index 83e3f6cc3250..8876c7807048 100644
> --- a/drivers/soundwire/sysfs_slave.c
> +++ b/drivers/soundwire/sysfs_slave.c
> @@ -184,18 +184,40 @@ static struct attribute *dp0_attrs[] = {
>  	NULL,
>  };
>  
> +static umode_t dp0_attr_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;
> +}
> +
> +static bool dp0_group_visible(struct kobject *kobj)
> +{
> +	struct sdw_slave *slave = dev_to_sdw_dev(kobj_to_dev(kobj));
> +
> +	if (slave->prop.dp0_prop)
> +		return true;
> +	return false;
> +}
> +DEFINE_SYSFS_GROUP_VISIBLE(dp0);

What do you think of the following for cases like these where
attr_visible is trivially derivable from group_visible?

diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index a42642b277dd..203d2e7e9a1e 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -117,6 +117,15 @@ struct attribute_group {
                return name##_attr_visible(kobj, attr, n);           \
        }
 
+#define DEFINE_SIMPLE_SYSFS_GROUP_VISIBLE(name)                      \
+       static inline umode_t sysfs_group_visible_##name(            \
+               struct kobject *kobj, struct attribute *a, int n) \
+       {                                                            \
+               if (n == 0 && !name##_group_visible(kobj))           \
+                       return SYSFS_GROUP_INVISIBLE;                \
+               return a->mode;                                      \
+       }
+
 /*
  * Same as DEFINE_SYSFS_GROUP_VISIBLE, but for groups with only binary
  * attributes

...i.e. don't require $prefix_attr_visible() to be defined?

With or without that:

Reviewed-by: Dan Williams <dan.j.williams@intel.com>