linux-kernel - Re: [PATCH v1 2/6] thermal: cpu_cooling: Support passing driver private data.

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Message-ID: <20140529120624.GA2593@e104805>
Date:	Thu, 29 May 2014 13:06:24 +0100
From:	"Javi Merino" <javi.merino@....com>
To:	Amit Daniel Kachhap <amit.daniel@...sung.com>
Cc:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"amit.kachhap@...il.com" <amit.kachhap@...il.com>,
	"rjw@...ysocki.net" <rjw@...ysocki.net>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"edubezval@...il.com" <edubezval@...il.com>,
	Zhang Rui <rui.zhang@...el.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"lenb@...nel.org" <lenb@...nel.org>
Subject: Re: [PATCH v1 2/6] thermal: cpu_cooling: Support passing driver
 private data.

Hi Amit,

One minor comment.

On Thu, May 29, 2014 at 09:15:30AM +0100, Amit Daniel Kachhap wrote:
> This patch allows the caller of cpufreq cooling APIs to register along
> with their driver data which will be useful while receiving any cooling states
> notifications.
> This patch is in preparation to add notfication support for cpufrequency
> cooling changes. This change also removes the unnecessary exposing of
> internal housekeeping structure via thermal_cooling_device->devdata to the
> users of cpufreq cooling APIs. As part of this implmentation, this private local
> structure (cpufreq_dev) is now stored in a list and scanned for each call to
> cpu cooling interfaces.
> 
> Signed-off-by: Amit Daniel Kachhap <amit.daniel@...sung.com>
> ---
>  Documentation/thermal/cpu-cooling-api.txt          |    3 +-
>  drivers/thermal/cpu_cooling.c                      |   89 ++++++++++++++++----
>  drivers/thermal/db8500_cpufreq_cooling.c           |    2 +-
>  drivers/thermal/samsung/exynos_thermal_common.c    |    2 +-
>  drivers/thermal/ti-soc-thermal/ti-thermal-common.c |    2 +-
>  include/linux/cpu_cooling.h                        |    5 +-
>  6 files changed, 80 insertions(+), 23 deletions(-)
> 
> diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
> index fca24c9..aaa07c6 100644
> --- a/Documentation/thermal/cpu-cooling-api.txt
> +++ b/Documentation/thermal/cpu-cooling-api.txt
> @@ -17,13 +17,14 @@ the user. The registration APIs returns the cooling device pointer.
> 
>  1.1 cpufreq registration/unregistration APIs
>  1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
> -       struct cpumask *clip_cpus)
> +       struct cpumask *clip_cpus, void *devdata)
> 
>      This interface function registers the cpufreq cooling device with the name
>      "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
>      cooling devices.
> 
>     clip_cpus: cpumask of cpus where the frequency constraints will happen.
> +   devdata: driver private data pointer.
> 
>  1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
> 
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> index 16388b0..6d145d5 100644
> --- a/drivers/thermal/cpu_cooling.c
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -50,16 +50,18 @@ struct cpufreq_cooling_device {
>         unsigned int cpufreq_state;
>         unsigned int cpufreq_val;
>         struct cpumask allowed_cpus;
> +       struct list_head node;
>  };
>  static DEFINE_IDR(cpufreq_idr);
>  static DEFINE_MUTEX(cooling_cpufreq_lock);
> 
> -static unsigned int cpufreq_dev_count;
> -
>  /* notify_table passes value to the CPUFREQ_ADJUST callback function. */
>  #define NOTIFY_INVALID NULL
>  static DEFINE_PER_CPU(struct cpufreq_cooling_device *, notify_device);
> 
> +/* A list to hold all the cpufreq cooling devices registered */
> +static LIST_HEAD(cpufreq_cooling_list);
> +
>  /**
>   * get_idr - function to get a unique id.
>   * @idr: struct idr * handle used to create a id.
> @@ -98,6 +100,26 @@ static void release_idr(struct idr *idr, int id)
> 
>  /* Below code defines functions to be used for cpufreq as cooling device */
> 
> +/**
> + * cpufreq_cooling_get_info - function to cpufreq_dev for the corresponding cdev
> + * @cdev: pointer of the cooling device
> + *
> + * This function will loop through the cpufreq_cooling_device list and
> + * return the matching device
> + *

You should add a "Locking:" section here which documents that this
function must be called with cooling_cpufreq_lock held.

Cheers,
Javi

> + * Return: cpufreq_cooling_device if matched with the cdev or NULL if not
> + * matched.
> + */
> +static inline struct cpufreq_cooling_device *
> +cpufreq_cooling_get_info(struct thermal_cooling_device *cdev)
> +{
> +       struct cpufreq_cooling_device *cpufreq_dev = NULL;
> +       list_for_each_entry(cpufreq_dev, &cpufreq_cooling_list, node)
> +               if (cpufreq_dev->cool_dev == cdev)
> +                       break;
> +       return cpufreq_dev;
> +}
> +


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