Re: [PATCH v2 2/7] driver: Add rescan hook to struct device

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

On 09.03.23 12:52, Sascha Hauer wrote:
> When devices are enabled with a device tree overlay the newly enabled
> devices can be probed by doing a of_probe(). This works fine for the
> regular platform devices, but doesn't work for devices which are not
> probed by the core, but by the subsystem. Prominent examples are I2C or
> SPI devices.
> 
> This patch adds a struct device::rescan hook that subsystems can
> implement to trigger rescanning the device nodes.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>

> ---
>  drivers/of/platform.c | 11 +++++------
>  include/driver.h      |  6 ++++++
>  2 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index edb082b106..2e9abe32bc 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -153,8 +153,10 @@ struct device *of_platform_device_create(struct device_node *np,
>  	 * Linux uses the OF_POPULATED flag to skip already populated/created
>  	 * devices.
>  	 */
> -	if (np->dev)
> +	if (np->dev) {
> +		device_rescan(np->dev);
>  		return np->dev;
> +	}
>  
>  	/* count the io resources */
>  	if (of_can_translate_address(np))
> @@ -420,11 +422,8 @@ static struct device *of_device_create_on_demand(struct device_node *np)
>  	if (!parent)
>  		return NULL;
>  
> -	if (!np->dev && parent->dev) {
> -		ret = device_detect(parent->dev);
> -		if (ret && ret != -ENOSYS)
> -			return ERR_PTR(ret);
> -	}
> +	if (!np->dev && parent->dev)
> +		device_rescan(parent->dev);
>  
>  	if (!np->dev)
>  		pr_debug("Creating device for %s\n", np->full_name);
> diff --git a/include/driver.h b/include/driver.h
> index f53668711b..91e1f01974 100644
> --- a/include/driver.h
> +++ b/include/driver.h
> @@ -91,6 +91,7 @@ struct device {
>  	 * when the driver should actually detect client devices
>  	 */
>  	int     (*detect) (struct device *);
> +	void	(*rescan) (struct device *);
>  
>  	/*
>  	 * if a driver probe is deferred, this stores the last error
> @@ -158,7 +159,12 @@ static inline void put_device(struct device *dev) {}
>  void free_device_res(struct device *dev);
>  void free_device(struct device *dev);
>  
> +static inline void device_rescan(struct device *dev)
> +{
> +	if (dev->rescan)
> +		dev->rescan(dev);
>  
> +}
>  /* Iterate over a devices children
>   */
>  #define device_for_each_child(dev, child) \

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