linux-kernel - Re: [PATCH 7/9] i2c: Switch .probe() to not take an id parameter

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Message-ID: <20230224170218.22c0af0c@booty>
Date:   Fri, 24 Feb 2023 17:02:18 +0100
From:   Luca Ceresoli <luca.ceresoli@...tlin.com>
To:     Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Cc:     Wolfram Sang <wsa@...nel.org>, kernel@...gutronix.de,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH 7/9] i2c: Switch .probe() to not take an id parameter

Hi Uwe,

On Fri, 24 Feb 2023 13:05:58 +0100
Uwe Kleine-König         <u.kleine-koenig@...gutronix.de> wrote:

> Commit b8a1a4cd5a98 ("i2c: Provide a temporary .probe_new() call-back
> type") introduced a new probe callback to convert i2c init routines to
> not take an i2c_device_id parameter. Now that all in-tree drivers are
> converted to the temporary .probe_new() callback, .probe() can be
> modified to match the desired prototype.
> 
> Now that .probe() and .probe_new() have the same semantic, they can be
> defined as members of an anonymous union to save some memory and
> simplify the core code a bit.
> 
> Signed-off-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>

Thank you, I love this cleanup!

> ---
>  drivers/i2c/i2c-core-base.c | 11 ++---------
>  include/linux/i2c.h         | 14 +++++++++-----
>  2 files changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
> index 087e480b624c..1fbe16221085 100644
> --- a/drivers/i2c/i2c-core-base.c
> +++ b/drivers/i2c/i2c-core-base.c
> @@ -558,15 +558,8 @@ static int i2c_device_probe(struct device *dev)
>  		goto err_detach_pm_domain;
>  	}
>  
> -	/*
> -	 * When there are no more users of probe(),
> -	 * rename probe_new to probe.
> -	 */
> -	if (driver->probe_new)
> -		status = driver->probe_new(client);
> -	else if (driver->probe)
> -		status = driver->probe(client,
> -				       i2c_match_id(driver->id_table, client));
> +	if (driver->probe)
> +		status = driver->probe(client);
>  	else
>  		status = -EINVAL;
>  
> diff --git a/include/linux/i2c.h b/include/linux/i2c.h
> index d84e0e99f084..c3e022d53182 100644
> --- a/include/linux/i2c.h
> +++ b/include/linux/i2c.h
> @@ -272,14 +272,18 @@ enum i2c_driver_flags {
>  struct i2c_driver {
>  	unsigned int class;
>  
> +	union {
>  	/* Standard driver model interfaces */
> -	int (*probe)(struct i2c_client *client, const struct i2c_device_id *id);
> +		int (*probe)(struct i2c_client *client);
> +		/*
> +		 * Legacy callback that was part of a conversion of .probe().
> +		 * Today it has the same semantic as .probe(). Don't use for new
> +		 * code.
> +		 */
> +		int (*probe_new)(struct i2c_client *client);
> +	};
>  	void (*remove)(struct i2c_client *client);
>  
> -	/* New driver model interface to aid the seamless removal of the
> -	 * current probe()'s, more commonly unused than used second parameter.
> -	 */
> -	int (*probe_new)(struct i2c_client *client);

The kerneldoc for this struct should also be updated:

- * @probe: Callback for device binding - soon to be deprecated
- * @probe_new: New callback for device binding
+ * @probe: Callback for device binding 
+ * @probe_new: Transitional callback for device binding - do not use

Otherwise LGTM.

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com