Re: [PATCH v8 5/6] PM / devfreq: Add PM QoS support

[Matthias Kaehlcke <mka@chromium.org>]

On Tue, Sep 24, 2019 at 01:11:29PM +0300, Leonard Crestez wrote:
> Register notifiers with the PM QoS framework in order to respond to
> requests for DEV_PM_QOS_MIN_FREQUENCY and DEV_PM_QOS_MAX_FREQUENCY.
> 
> No notifiers are added by this patch but PM QoS constraints can be
> imposed externally (for example from other devices).
> 
> Signed-off-by: Leonard Crestez <leonard.crestez@nxp.com>
> Reviewed-by: Matthias Kaehlcke <mka@chromium.org>
> ---
>  drivers/devfreq/devfreq.c | 75 +++++++++++++++++++++++++++++++++++++++
>  include/linux/devfreq.h   |  5 +++
>  2 files changed, 80 insertions(+)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index eee403e70c84..784f3e40536a 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -22,15 +22,18 @@
>  #include <linux/platform_device.h>
>  #include <linux/list.h>
>  #include <linux/printk.h>
>  #include <linux/hrtimer.h>
>  #include <linux/of.h>
> +#include <linux/pm_qos.h>
>  #include "governor.h"
>  
>  #define CREATE_TRACE_POINTS
>  #include <trace/events/devfreq.h>
>  
> +#define HZ_PER_KHZ	1000
> +
>  static struct class *devfreq_class;
>  
>  /*
>   * devfreq core provides delayed work based load monitoring helper
>   * functions. Governors can use these or can implement their own
> @@ -109,10 +112,11 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
>  static void get_freq_range(struct devfreq *devfreq,
>  			   unsigned long *min_freq,
>  			   unsigned long *max_freq)
>  {
>  	unsigned long *freq_table = devfreq->profile->freq_table;
> +	unsigned long qos_min_freq, qos_max_freq;
>  
>  	lockdep_assert_held(&devfreq->lock);
>  
>  	/*
>  	 * Init min/max frequency from freq table.
> @@ -125,10 +129,18 @@ static void get_freq_range(struct devfreq *devfreq,
>  	} else {
>  		*min_freq = freq_table[devfreq->profile->max_state - 1];
>  		*max_freq = freq_table[0];
>  	}
>  
> +	/* constraints from PM QoS */
> +	qos_min_freq = dev_pm_qos_read_value(devfreq->dev.parent,
> +					     DEV_PM_QOS_MIN_FREQUENCY);
> +	qos_max_freq = dev_pm_qos_read_value(devfreq->dev.parent,
> +					     DEV_PM_QOS_MIN_FREQUENCY);

This needs to be DEV_PM_QOS_MAX_FREQUENCY. I missed this in the earlier
reviews, but stumbled across it when testing.

!Reviewed-by: Matthias Kaehlcke <mka@chromium.org>