linux-kernel - Re: [RFC PATCH 2/5] thermal: cpu_cooling: Add notifications support for the clients

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Message-ID: <20140516173226.GE2856@e102654-lin.cambridge.arm.com>
Date:	Fri, 16 May 2014 18:32:26 +0100
From:	Javi Merino <javi.merino@....com>
To:	Amit Daniel Kachhap <amit.daniel@...sung.com>
Cc:	"linux-pm@...ts.linux-foundation.org" 
	<linux-pm@...ts.linux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"lenb@...nel.org" <lenb@...nel.org>,
	"rui.zhang@...el.com" <rui.zhang@...el.com>, edubezval@...il.com,
	"rjw@...ysocki.net" <rjw@...ysocki.net>
Subject: Re: [RFC PATCH 2/5] thermal: cpu_cooling: Add notifications support
 for the clients

Hi Amit,

On Thu, May 08, 2014 at 03:37:57PM +0100, Amit Daniel Kachhap wrote:
> This patch adds notification support for those clients of cpu_cooling
> APIs which may want to do something interesting after receiving these
> cpu_cooling events. The notifier structure passed is of both Set/Get type.
> The notfications events can be of type,
> 1. CPU_COOLING_SET_STATE_PRE
> 2. CPU_COOLING_SET_STATE_POST
> 3. CPU_COOLING_GET_CUR_STATE
> 4. CPU_COOLING_GET_MAX_STATE
> 
> The advantages of these notfications is to differentiate between different
> P states in the cpufreq table and the cooling states. The clients of these
> events may group few P states into 1 cooling states. Also some more cooling
> states can be enabled when the maximum of P state is reached. Post notifications
> can be used for those cases.
> 
> Signed-off-by: Amit Daniel Kachhap <amit.daniel@...sung.com>
> ---
>  drivers/thermal/cpu_cooling.c |   99 +++++++++++++++++++++++++++++++++++++++-
>  include/linux/cpu_cooling.h   |   55 +++++++++++++++++++++++
>  2 files changed, 151 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
> index 21f44d4..e2aeb36 100644
> --- a/drivers/thermal/cpu_cooling.c
> +++ b/drivers/thermal/cpu_cooling.c
> @@ -50,6 +50,7 @@ struct cpufreq_cooling_device {
>  	unsigned int cpufreq_state;
>  	unsigned int cpufreq_val;
>  	struct cpumask allowed_cpus;
> +	struct cpufreq_cooling_status request_status;
>  	struct list_head node;
>  };
>  static DEFINE_IDR(cpufreq_idr);
> @@ -59,6 +60,8 @@ static DEFINE_MUTEX(cooling_cpufreq_lock);
>  #define NOTIFY_INVALID NULL
>  static struct cpufreq_cooling_device *notify_device;
>  
> +/* Notfier list to validates/updates the cpufreq cooling states */
> +static BLOCKING_NOTIFIER_HEAD(cpufreq_cooling_state_notifier_list);
>  /* A list to hold all the cpufreq cooling devices registered */
>  static LIST_HEAD(cpufreq_cooling_list);
>  
> @@ -266,6 +269,21 @@ static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
>  	return freq;
>  }
>  
> +static int
> +cpufreq_cooling_notify_states(struct cpufreq_cooling_status *request,
> +			enum cpu_cooling_state_ops op)
> +{
> +	/* Invoke the notifiers which have registered for this state change */
> +	if (op == CPU_COOLING_SET_STATE_PRE ||
> +		op == CPU_COOLING_SET_STATE_POST ||
> +		op == CPU_COOLING_GET_MAX_STATE ||
> +		op == CPU_COOLING_GET_CUR_STATE) {
> +		blocking_notifier_call_chain(
> +			&cpufreq_cooling_state_notifier_list, op, request);
> +	}
> +	return 0;
> +}
> +
>  /**
>   * cpufreq_apply_cooling - function to apply frequency clipping.
>   * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
> @@ -285,9 +303,18 @@ static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
>  	struct cpumask *mask = &cpufreq_device->allowed_cpus;
>  	unsigned int cpu = cpumask_any(mask);
>  
> +	cpufreq_device->request_status.cur_state =
> +						cpufreq_device->cpufreq_state;
> +	cpufreq_device->request_status.new_state = cooling_state;
> +
> +	cpufreq_cooling_notify_states(&cpufreq_device->request_status,
> +					CPU_COOLING_SET_STATE_PRE);
> +
> +	cooling_state = cpufreq_device->request_status.new_state;
>  
>  	/* Check if the old cooling action is same as new cooling action */
> -	if (cpufreq_device->cpufreq_state == cooling_state)
> +	if (cpufreq_device->cpufreq_state ==
> +				cpufreq_device->request_status.new_state)
>  		return 0;
>  
>  	clip_freq = get_cpu_frequency(cpu, cooling_state);
> @@ -304,7 +331,8 @@ static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
>  	}
>  
>  	notify_device = NOTIFY_INVALID;
> -
> +	cpufreq_cooling_notify_states(&cpufreq_device->request_status,
> +					CPU_COOLING_SET_STATE_POST);
>  	return 0;
>  }
>  
> @@ -383,6 +411,11 @@ static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
>  	if (count > 0)
>  		*state = count;
>  
> +	cpufreq_device->request_status.max_state = count;
> +	cpufreq_cooling_notify_states(&cpufreq_device->request_status,
> +					CPU_COOLING_GET_MAX_STATE);
> +	*state = cpufreq_device->request_status.max_state;
> +

I think this should all be inside the "if (count > 0)".  If not, then
remove it, as it is dead code now.

Cheers,
Javi

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