Re: [RFC PATCH 4/5] w1: add a callback to call slave when a new device is connected

From: Mathieu Poirier
Date: Wed Oct 26 2016 - 12:42:38 EST


On 26 October 2016 at 08:57, Antoine Tenart
<antoine.tenart@xxxxxxxxxxxxxxxxxx> wrote:
> This patch adds the possibility for slave drivers to register a
> callback, to be called whenever a new device matching the slave ID
> is connected.
>
> Signed-off-by: Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/w1/w1.c | 10 ++++++++++
> drivers/w1/w1_family.h | 2 ++
> 2 files changed, 12 insertions(+)
>
> diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
> index 80d0cc4e6e7f..7010ffd1ea93 100644
> --- a/drivers/w1/w1.c
> +++ b/drivers/w1/w1.c
> @@ -659,6 +659,16 @@ static int w1_family_notify(unsigned long action, struct w1_slave *sl)
> return err;
> }
> }
> + if (fops->callback) {
> + err = fops->callback(sl);
> + /*
> + * Do not return an error as the slave driver correctly
> + * probed.
> + */

I don't get this part. What's the point of calling a callback if a
failure is not important - maybe I'm just missing something.

> + if (err)
> + dev_err(&sl->dev,
> + "callback call failed. err=%d\n", err);
> + }
>
> break;
> case BUS_NOTIFY_DEL_DEVICE:
> diff --git a/drivers/w1/w1_family.h b/drivers/w1/w1_family.h
> index 10a7a0767187..5e165babc6f3 100644
> --- a/drivers/w1/w1_family.h
> +++ b/drivers/w1/w1_family.h
> @@ -55,11 +55,13 @@ struct w1_slave;
> * @add_slave: add_slave
> * @remove_slave: remove_slave
> * @groups: sysfs group
> + * @callback: called when a new device is discovered
> */
> struct w1_family_ops
> {
> int (* add_slave)(struct w1_slave *);
> void (* remove_slave)(struct w1_slave *);
> + int (* callback)(struct w1_slave *);
> const struct attribute_group **groups;
> };
>
> --
> 2.10.1
>