linux-kernel - Re: [PATCH 01/20] mfd: Add devm_ apis for mfd_add_devices and mfd_release

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Message-ID: <20160407104403.GZ3323@x1>
Date:	Thu, 7 Apr 2016 11:44:03 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Laxman Dewangan <ldewangan@...dia.com>
Cc:	corbet@....net, andreas.werner@....de, tony@...mide.com,
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, patches@...nsource.wolfsonmicro.com
Subject: Re: [PATCH 01/20] mfd: Add devm_ apis for mfd_add_devices and
 mfd_release_devices

On Tue, 05 Apr 2016, Laxman Dewangan wrote:

> Add device managed APIs devm_mfd_add_devices() and
> devm_mfd_remove_devices() for the APIs mfd_add_devices()
> and mfd_remove_devices().

Nit: Line wrap after "devm_mfd_remove_devices()" instead.

> This helps in reducing code in error path and sometimes
> removal of .remove callback for driver unbind.

s/for/during/

> Signed-off-by: Laxman Dewangan <ldewangan@...dia.com>
> ---
>  drivers/mfd/mfd-core.c   | 62 ++++++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/mfd/core.h |  7 ++++++
>  2 files changed, 69 insertions(+)
> 
> diff --git a/drivers/mfd/mfd-core.c b/drivers/mfd/mfd-core.c
> index 409da01..145712e 100644
> --- a/drivers/mfd/mfd-core.c
> +++ b/drivers/mfd/mfd-core.c
> @@ -334,6 +334,68 @@ void mfd_remove_devices(struct device *parent)
>  }
>  EXPORT_SYMBOL(mfd_remove_devices);
>  
> +static void devm_mfd_dev_release(struct device *dev, void *res)
> +{
> +	mfd_remove_devices(dev);
> +}
> +
> +/**
> + * devm_mfd_add_devices - Resource managed version of mfd_add_devices()
> + *
> + * This returns the 0 on success otherwise error number in the failure.

"Returns 0 on success or an appropriate negative error number on failure."

> + * The allocated mfd devices will automatically be released when the

s/mfd/MFD/

> + * device is unbound.
> + */
> +int devm_mfd_add_devices(struct device *dev, int id,
> +		    const struct mfd_cell *cells, int n_devs,
> +		    struct resource *mem_base,
> +		    int irq_base, struct irq_domain *domain)
> +{
> +	struct device **ptr;
> +	int ret;
> +
> +	ptr = devres_alloc(devm_mfd_dev_release, sizeof(*ptr), GFP_KERNEL);
> +	if (!ptr)
> +		return -ENOMEM;
> +
> +	ret = mfd_add_devices(dev, id, cells, n_devs, mem_base,
> +			      irq_base, domain);
> +	if (!ret) {
> +		*ptr = dev;
> +		devres_add(dev, ptr);
> +	} else {
> +		devres_free(ptr);
> +	}

Switch these round.  If you encounter a problem, free and return.  If
not, skip the error handling and add the device outside of the if().

> +	return ret;
> +}
> +EXPORT_SYMBOL(devm_mfd_add_devices);
> +
> +static int devm_mfd_devs_match(struct device *dev, void *res, void *data)
> +{
> +	struct device **r = res;
> +
> +	if (WARN_ON(!r || !*r))
> +		return 0;
> +
> +	return *r == data;
> +}
> +
> +/**
> + * devm_mfd_remove_device - Resource managed version of mfd_remove_devices()
> + * @dev: Device for which which resource was allocated.

Did you proof read your own writing?  Pleaes re-word.

> + * Remove all mfd devices added on the device.

s/mfd/MFD/

'D' already means devices, so here you are saying "devices devices".
Please re-word.  Besides, you need to be more specific as to which
"devices on the devices" you are detailing, since this sentence
doesn't really make a great deal of sense.

> + * Normally this function will not need to be called and the resource
> + * management code will ensure that the resource is freed.

Then what is the purpose of providing it?  Do you have a user?

> + */
> +void devm_mfd_remove_devices(struct device *dev)
> +{
> +	WARN_ON(devres_release(dev, devm_mfd_dev_release,
> +			       devm_mfd_devs_match, dev));
> +}
> +EXPORT_SYMBOL(devm_mfd_remove_devices);
> +
>  int mfd_clone_cell(const char *cell, const char **clones, size_t n_clones)
>  {
>  	struct mfd_cell cell_entry;
> diff --git a/include/linux/mfd/core.h b/include/linux/mfd/core.h
> index bc6f7e0..d658d7f 100644
> --- a/include/linux/mfd/core.h
> +++ b/include/linux/mfd/core.h
> @@ -131,4 +131,11 @@ static inline int mfd_add_hotplug_devices(struct device *parent,
>  
>  extern void mfd_remove_devices(struct device *parent);
>  
> +extern int devm_mfd_add_devices(struct device *dev, int id,
> +			   const struct mfd_cell *cells, int n_devs,
> +			   struct resource *mem_base,
> +			   int irq_base, struct irq_domain *irq_domain);
> +
> +extern void devm_mfd_remove_devices(struct device *dev);
> +
>  #endif

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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