linux-kernel - Re: [PATCH] devfreq_cooling: pass a pointer to devfreq in the power model callbacks

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Message-ID: <20160620173617.GC2941@e104805>
Date:	Mon, 20 Jun 2016 18:36:17 +0100
From:	Javi Merino <javi.merino@....com>
To:	linux-pm@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, lukasz.luba@....com,
	Zhang Rui <rui.zhang@...el.com>,
	Eduardo Valentin <edubezval@...il.com>
Subject: Re: [PATCH] devfreq_cooling: pass a pointer to devfreq in the power
 model callbacks

Eduardo, Rui,

On Fri, Jun 03, 2016 at 10:25:31AM +0100, Javi Merino wrote:
> When the devfreq cooling device was designed, it was an oversight not to
> pass a pointer to the struct devfreq as the first parameters of the
> callbacks.  The design patterns of the kernel suggest it for a good
> reason.
> 
> By passing a pointer to struct devfreq, the driver can register one
> function that works with multiple devices.  With the current
> implementation, a driver that can work with multiple devices has to
> create multiple copies of the same function with different parameters so
> that each devfreq_cooling_device can use the appropriate one.  By
> passing a pointer to struct devfreq, the driver can identify which
> device it's referring to.
> 
> Cc: Zhang Rui <rui.zhang@...el.com>
> Cc: Eduardo Valentin <edubezval@...il.com>
> Reviewed-by: Punit Agrawal <punit.agrawal@....com>
> Signed-off-by: Javi Merino <javi.merino@....com>
> ---
>  drivers/thermal/devfreq_cooling.c | 5 +++--
>  include/linux/devfreq_cooling.h   | 6 ++++--
>  2 files changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/thermal/devfreq_cooling.c b/drivers/thermal/devfreq_cooling.c
> index 01f0015f80dc..c549d83a0c7d 100644
> --- a/drivers/thermal/devfreq_cooling.c
> +++ b/drivers/thermal/devfreq_cooling.c
> @@ -238,7 +238,7 @@ get_static_power(struct devfreq_cooling_device *dfc, unsigned long freq)
>  		return 0;
>  	}
>  
> -	return dfc->power_ops->get_static_power(voltage);
> +	return dfc->power_ops->get_static_power(df, voltage);
>  }
>  
>  /**
> @@ -262,7 +262,8 @@ get_dynamic_power(struct devfreq_cooling_device *dfc, unsigned long freq,
>  	struct devfreq_cooling_power *dfc_power = dfc->power_ops;
>  
>  	if (dfc_power->get_dynamic_power)
> -		return dfc_power->get_dynamic_power(freq, voltage);
> +		return dfc_power->get_dynamic_power(dfc->devfreq, freq,
> +						    voltage);
>  
>  	freq_mhz = freq / 1000000;
>  	power = (u64)dfc_power->dyn_power_coeff * freq_mhz * voltage * voltage;
> diff --git a/include/linux/devfreq_cooling.h b/include/linux/devfreq_cooling.h
> index 7adf6cc4b305..959714e93e5b 100644
> --- a/include/linux/devfreq_cooling.h
> +++ b/include/linux/devfreq_cooling.h
> @@ -37,8 +37,10 @@
>   *			@dyn_power_coeff * frequency * voltage^2
>   */
>  struct devfreq_cooling_power {
> -	unsigned long (*get_static_power)(unsigned long voltage);
> -	unsigned long (*get_dynamic_power)(unsigned long freq,
> +	unsigned long (*get_static_power)(struct devfreq *devfreq,
> +					  unsigned long voltage);
> +	unsigned long (*get_dynamic_power)(struct devfreq *devfreq,
> +					   unsigned long freq,
>  					   unsigned long voltage);
>  	unsigned long dyn_power_coeff;
>  };

If there are no objections, can you pick this for the next merge
window?

Thanks,
Javi