linux-kernel - Re: [PATCH] base: platform: name the device already during allocation

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Date:	Wed, 28 May 2014 13:58:06 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Heikki Krogerus <heikki.krogerus@...ux.intel.com>
Cc:	Russell King <linux@....linux.org.uk>,
	Jean Delvare <khali@...ux-fr.org>,
	Vivek Gautam <gautam.vivek@...sung.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] base: platform: name the device already during allocation

On Mon, Apr 28, 2014 at 03:09:27PM +0300, Heikki Krogerus wrote:
> This allows resources such as GPIOs and clocks, which can be
> matched based on the device name when requested, to be
> assigned even when PLATFORM_DEVID_AUTO is used.

Why would anyone want to do that?

> 
> Signed-off-by: Heikki Krogerus <heikki.krogerus@...ux.intel.com>
> ---
>  drivers/base/platform.c | 77 ++++++++++++++++++++++++++++++-------------------
>  1 file changed, 47 insertions(+), 30 deletions(-)
> 
> diff --git a/drivers/base/platform.c b/drivers/base/platform.c
> index 5b47210..697896d 100644
> --- a/drivers/base/platform.c
> +++ b/drivers/base/platform.c
> @@ -174,11 +174,45 @@ struct platform_object {
>   */
>  void platform_device_put(struct platform_device *pdev)
>  {
> -	if (pdev)
> -		put_device(&pdev->dev);
> +	if (!pdev)
> +		return;
> +
> +	if (pdev->id_auto) {
> +		ida_simple_remove(&platform_devid_ida, pdev->id);
> +		pdev->id = PLATFORM_DEVID_AUTO;
> +	}
> +
> +	put_device(&pdev->dev);
>  }
>  EXPORT_SYMBOL_GPL(platform_device_put);
>  
> +static int pdev_set_name(struct platform_device *pdev)
> +{
> +	int ret;
> +
> +	switch (pdev->id) {
> +	default:
> +		return dev_set_name(&pdev->dev, "%s.%d", pdev->name,  pdev->id);
> +	case PLATFORM_DEVID_NONE:
> +		return dev_set_name(&pdev->dev, "%s", pdev->name);
> +	case PLATFORM_DEVID_AUTO:
> +		/*
> +		 * Automatically allocated device ID. We mark it as such so
> +		 * that we remember it must be freed, and we append a suffix
> +		 * to avoid namespace collision with explicit IDs.
> +		 */
> +		ret = ida_simple_get(&platform_devid_ida, 0, 0, GFP_KERNEL);
> +		if (ret < 0)
> +			return ret;
> +		pdev->id = ret;
> +		pdev->id_auto = true;
> +		return dev_set_name(&pdev->dev, "%s.%d.auto", pdev->name,
> +				    pdev->id);
> +	}
> +
> +	return 0;
> +}
> +
>  static void platform_device_release(struct device *dev)
>  {
>  	struct platform_object *pa = container_of(dev, struct platform_object,
> @@ -211,6 +245,10 @@ struct platform_device *platform_device_alloc(const char *name, int id)
>  		device_initialize(&pa->pdev.dev);
>  		pa->pdev.dev.release = platform_device_release;
>  		arch_setup_pdev_archdata(&pa->pdev);
> +		if (pdev_set_name(&pa->pdev)) {
> +			kfree(pa);
> +			return NULL;
> +		}
>  	}
>  
>  	return pa ? &pa->pdev : NULL;
> @@ -291,28 +329,6 @@ int platform_device_add(struct platform_device *pdev)
>  
>  	pdev->dev.bus = &platform_bus_type;
>  
> -	switch (pdev->id) {
> -	default:
> -		dev_set_name(&pdev->dev, "%s.%d", pdev->name,  pdev->id);
> -		break;
> -	case PLATFORM_DEVID_NONE:
> -		dev_set_name(&pdev->dev, "%s", pdev->name);
> -		break;
> -	case PLATFORM_DEVID_AUTO:
> -		/*
> -		 * Automatically allocated device ID. We mark it as such so
> -		 * that we remember it must be freed, and we append a suffix
> -		 * to avoid namespace collision with explicit IDs.
> -		 */
> -		ret = ida_simple_get(&platform_devid_ida, 0, 0, GFP_KERNEL);
> -		if (ret < 0)
> -			goto err_out;
> -		pdev->id = ret;
> -		pdev->id_auto = true;
> -		dev_set_name(&pdev->dev, "%s.%d.auto", pdev->name, pdev->id);
> -		break;
> -	}
> -
>  	for (i = 0; i < pdev->num_resources; i++) {
>  		struct resource *p, *r = &pdev->resource[i];
>  
> @@ -355,7 +371,6 @@ int platform_device_add(struct platform_device *pdev)
>  			release_resource(r);
>  	}
>  
> - err_out:
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(platform_device_add);
> @@ -375,11 +390,6 @@ void platform_device_del(struct platform_device *pdev)
>  	if (pdev) {
>  		device_del(&pdev->dev);
>  
> -		if (pdev->id_auto) {
> -			ida_simple_remove(&platform_devid_ida, pdev->id);
> -			pdev->id = PLATFORM_DEVID_AUTO;
> -		}
> -
>  		for (i = 0; i < pdev->num_resources; i++) {
>  			struct resource *r = &pdev->resource[i];
>  			unsigned long type = resource_type(r);
> @@ -397,8 +407,15 @@ EXPORT_SYMBOL_GPL(platform_device_del);
>   */
>  int platform_device_register(struct platform_device *pdev)
>  {
> +	int ret;
> +
>  	device_initialize(&pdev->dev);
>  	arch_setup_pdev_archdata(pdev);
> +
> +	ret = pdev_set_name(pdev);
> +	if (ret)
> +		return ret;
> +
>  	return platform_device_add(pdev);
>  }
>  EXPORT_SYMBOL_GPL(platform_device_register);
> -- 
> 2.0.0.rc0

I don't understand the usage of this, what drivers want/need this
change?

greg k-h
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