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

From: Chanwoo Choi <cw00.choi@samsung•com>
To: Leonard Crestez <leonard.crestez@nxp•com>,
	Matthias Kaehlcke <mka@chromium•org>
Cc: "Artur Świgoń" <a.swigon@partner•samsung.com>,
	"Abel Vesa" <abel.vesa@nxp•com>,
	"Saravana Kannan" <saravanak@google•com>,
	"linux-pm@vger•kernel.org" <linux-pm@vger•kernel.org>,
	"Viresh Kumar" <viresh.kumar@linaro•org>,
	dl-linux-imx <linux-imx@nxp•com>,
	"Krzysztof Kozlowski" <krzk@kernel•org>,
	"Lukasz Luba" <l.luba@partner•samsung.com>,
	"Kyungmin Park" <kyungmin.park@samsung•com>,
	"MyungJoo Ham" <myungjoo.ham@samsung•com>,
	"Alexandre Bailon" <abailon@baylibre•com>,
	"Georgi Djakov" <georgi.djakov@linaro•org>,
	"linux-arm-kernel@lists•infradead.org"
	<linux-arm-kernel@lists•infradead.org>,
	"Jacky Bai" <ping.bai@nxp•com>
Subject: Re: [PATCH v8 5/6] PM / devfreq: Add PM QoS support
Date: Thu, 26 Sep 2019 10:08:02 +0900	[thread overview]
Message-ID: <48e271f5-58d3-845a-538f-6fb75eb3deb6@samsung.com> (raw)
In-Reply-To: <VI1PR04MB7023910B94E4920D329427C8EE870@VI1PR04MB7023.eurprd04.prod.outlook.com>

Hi,

On 19. 9. 26. 오전 4:40, Leonard Crestez wrote:
> On 25.09.2019 05:13, Chanwoo Choi wrote:
>> On 19. 9. 25. 오전 4:22, Leonard Crestez wrote:
>>> On 24.09.2019 22:11, Matthias Kaehlcke wrote:
>>>> 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>
>>>
>>> I broke it in v8 while processing comments. Thanks for catching it.
>>
>> Did you test this patchset with v8?
>> Maybe it is not working with this mistake.
> 
> I ran some scripts which test that min_freq requests work as expected 
> (using imx interconnect+devfreq). They don't touch max_freq.

We always have to test the code before contributing the patch.
Please test all cases for these patches.

> 
> --
> Regards,
> Leonard
> 

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

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