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From: Dmitry Osipenko <digetx@gmail.com>
To: Chanwoo Choi <cw00.choi@samsung.com>
Cc: Thierry Reding <thierry.reding@gmail.com>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Jonathan Hunter <jonathanh@nvidia.com>,
	Tomeu Vizoso <tomeu.vizoso@collabora.com>,
	linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 21/24] PM / devfreq: tegra30: Synchronize average count on target's update
Date: Fri, 19 Jul 2019 19:46:18 +0300
Message-ID: <fc9cacc8-aa89-803a-dd82-7506965f987a@gmail.com> (raw)
In-Reply-To: <eed89254-9960-7572-635c-12b114821e85@samsung.com>

19.07.2019 4:40, Chanwoo Choi пишет:
> On 19. 7. 19. 오전 9:31, Dmitry Osipenko wrote:
>> В Thu, 18 Jul 2019 19:15:54 +0900
>> Chanwoo Choi <cw00.choi@samsung.com> пишет:
>>
>>> On 19. 7. 8. 오전 7:33, Dmitry Osipenko wrote:
>>>> The average count may get out of sync if interrupt was disabled /
>>>> avoided for a long time due to upper watermark optimization, hence
>>>> it should be re-synced on each target's update to ensure that
>>>> watermarks are set up correctly on EMC rate-change notification and
>>>> that a correct frequency is selected for device.
>>>>
>>>> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
>>>> ---
>>>>  drivers/devfreq/tegra30-devfreq.c | 30
>>>> ++++++++++++++++++++++++++++++ 1 file changed, 30 insertions(+)
>>>>
>>>> diff --git a/drivers/devfreq/tegra30-devfreq.c
>>>> b/drivers/devfreq/tegra30-devfreq.c index
>>>> 4d582809acb6..8a674fad26be 100644 ---
>>>> a/drivers/devfreq/tegra30-devfreq.c +++
>>>> b/drivers/devfreq/tegra30-devfreq.c @@ -466,11 +466,41 @@ static
>>>> void actmon_isr_device(struct tegra_devfreq *tegra,
>>>> dev->boost_freq, cpufreq_get(0)); }
>>>>  
>>>> +static void tegra_devfreq_sync_avg_count(struct tegra_devfreq
>>>> *tegra,
>>>> +					 struct
>>>> tegra_devfreq_device *dev) +{
>>>> +	u32 avg_count, avg_freq, old_upper, new_upper;
>>>> +
>>>> +	avg_count = device_readl(dev, ACTMON_DEV_AVG_COUNT);
>>>> +	avg_freq = avg_count / ACTMON_SAMPLING_PERIOD;
>>>> +
>>>> +	old_upper = tegra_actmon_upper_freq(tegra, dev->avg_freq);
>>>> +	new_upper = tegra_actmon_upper_freq(tegra, avg_freq);
>>>> +
>>>> +	/* similar to ISR, see comments in actmon_isr_device() */
>>>> +	if (old_upper != new_upper) {
>>>> +		dev->avg_freq = avg_freq;
>>>> +		dev->boost_freq = 0;
>>>> +	}
>>>> +}
>>>> +
>>>>  static unsigned long actmon_update_target(struct tegra_devfreq
>>>> *tegra, struct tegra_devfreq_device *dev)
>>>>  {
>>>>  	unsigned long target_freq;
>>>>  
>>>> +	/*
>>>> +	 * The avg_count / avg_freq is getting snapshoted on
>>>> device's
>>>> +	 * interrupt, but there are cases where actual value need
>>>> to
>>>> +	 * be utilized on target's update, like CPUFreq boosting
>>>> and
>>>> +	 * overriding the min freq
>>>> via /sys/class/devfreq/devfreq0/min_freq
>>>> +	 * because we're optimizing the upper watermark based on
>>>> the
>>>> +	 * actual EMC frequency. This means that interrupt may be
>>>> +	 * inactive for a long time and thus making snapshoted
>>>> value
>>>> +	 * outdated.
>>>> +	 */
>>>> +	tegra_devfreq_sync_avg_count(tegra, dev);  
>>>
>>> I think that you don't need to add the separate function to calculate
>>> the 'dev->avg_freq'. It is enough with your detailed comment to add
>>> this code in this function.
>>
>> The separate function is indeed not mandatory here, but I'm finding that
>> it usually makes easier to read and follow the code when it is properly
>> split up into logical blocks. Don't you agree?
> 
> It is right to make the separate function if function is too long or 
> function is called on the multiple points.
> 
> But, in this case, I think that it is enough to add this code
> to the actmon_update_target() because you already added the detailed comment. 
> 
> It is enough to understand the role of this code with your comment.

That's another personal preference, but I'm fine with yours variant as
well. Will change this in the next version.

>>
>>>> +
>>>>  	target_freq = min(dev->avg_freq + dev->boost_freq,
>>>> KHZ_MAX); target_freq = tegra_actmon_account_cpu_freq(tegra, dev,
>>>> target_freq); 
>>>>   
>>>
>>> And also, is it impossible to squash this patch with patch19/patch20?
>>>
>>
>> It should be possible to squash this patch with #20, but wouldn't
>> be better to keep changes in the chronological order? It's also better
>> to keep changes separate simply to aid bisection in case of a problem.
>>
>>
>>
> 
> 


  reply index

Thread overview: 94+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-07 22:32 [PATCH v4 00/24] More improvements for Tegra30 devfreq driver Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 01/24] PM / devfreq: tegra30: Change irq type to unsigned int Dmitry Osipenko
2019-07-16 11:35   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 02/24] PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped Dmitry Osipenko
2019-07-16 11:47   ` Chanwoo Choi
2019-07-16 13:03     ` Dmitry Osipenko
2019-07-17  6:37       ` Chanwoo Choi
2019-07-17 16:44         ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 03/24] PM / devfreq: tegra30: Handle possible round-rate error Dmitry Osipenko
2019-07-16 11:50   ` Chanwoo Choi
2019-07-16 13:09     ` Dmitry Osipenko
2019-07-17  6:38       ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 04/24] PM / devfreq: tegra30: Drop write-barrier Dmitry Osipenko
2019-07-16 11:51   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 05/24] PM / devfreq: tegra30: Set up watermarks properly Dmitry Osipenko
2019-07-18 10:17   ` Chanwoo Choi
2019-07-19  0:00     ` Dmitry Osipenko
2019-07-19  1:31       ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 06/24] PM / devfreq: tegra30: Tune up boosting thresholds Dmitry Osipenko
2019-07-16 11:55   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 07/24] PM / devfreq: tegra30: Use CPUFreq notifier Dmitry Osipenko
2019-07-16 12:08   ` Chanwoo Choi
2019-07-16 13:18     ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 08/24] PM / devfreq: tegra30: Move clk-notifier's registration to governor's start Dmitry Osipenko
2019-07-16 12:11   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 09/24] PM / devfreq: tegra30: Reset boosting on startup Dmitry Osipenko
2019-07-16 12:13   ` Chanwoo Choi
2019-07-16 13:19     ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 10/24] PM / devfreq: tegra30: Don't enable consecutive-down interrupt " Dmitry Osipenko
2019-07-16 12:17   ` Chanwoo Choi
2019-07-16 15:17     ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 11/24] PM / devfreq: tegra30: Add debug messages Dmitry Osipenko
2019-07-16 12:23   ` Chanwoo Choi
2019-07-16 13:26     ` Dmitry Osipenko
2019-07-17  6:45       ` Chanwoo Choi
2019-07-17 15:46         ` Dmitry Osipenko
2019-07-18  9:07           ` Chanwoo Choi
2019-07-19  1:13             ` Dmitry Osipenko
2019-07-19  1:22               ` Chanwoo Choi
2019-07-19 17:10                 ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 12/24] PM / devfreq: tegra30: Inline all one-line functions Dmitry Osipenko
2019-07-16 12:26   ` Chanwoo Choi
2019-07-16 13:35     ` Dmitry Osipenko
2019-07-18  9:09       ` Chanwoo Choi
2019-07-19  1:22         ` Dmitry Osipenko
2019-07-19  1:24           ` Chanwoo Choi
2019-07-19  1:27             ` Chanwoo Choi
2019-07-19  2:14               ` Dmitry Osipenko
2019-07-19  6:01                 ` Chanwoo Choi
2019-07-19 16:52                   ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 13/24] PM / devfreq: tegra30: Constify structs Dmitry Osipenko
2019-07-16 12:26   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 14/24] PM / devfreq: tegra30: Ensure that target freq won't overflow Dmitry Osipenko
2019-07-16 12:30   ` Chanwoo Choi
2019-07-16 13:59     ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 15/24] PM / devfreq: tegra30: Fix integer overflow on CPU's freq max out Dmitry Osipenko
2019-07-16 12:32   ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 16/24] PM / devfreq: tegra30: Use kHz units uniformly in the code Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 17/24] PM / devfreq: tegra30: Use tracepoints for debugging Dmitry Osipenko
2019-07-18  9:47   ` Chanwoo Choi
2019-07-19  0:49     ` Dmitry Osipenko
2019-07-19  1:01       ` Chanwoo Choi
2019-07-19  1:50         ` Dmitry Osipenko
2019-07-07 22:32 ` [PATCH v4 18/24] PM / devfreq: tegra30: Optimize CPUFreq notifier Dmitry Osipenko
2019-07-18  9:48   ` Chanwoo Choi
2019-07-19  0:42     ` Dmitry Osipenko
2019-07-19  1:09       ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 19/24] PM / devfreq: tegra30: Optimize upper consecutive watermark selection Dmitry Osipenko
2019-07-18  9:51   ` Chanwoo Choi
2019-07-19  0:40     ` Dmitry Osipenko
2019-07-19  1:15       ` Chanwoo Choi
2019-07-19  1:17         ` Chanwoo Choi
2019-07-07 22:32 ` [PATCH v4 20/24] PM / devfreq: tegra30: Optimize upper average " Dmitry Osipenko
2019-07-19  1:36   ` Chanwoo Choi
2019-07-19  1:59     ` Dmitry Osipenko
2019-07-19  2:06       ` Chanwoo Choi
2019-07-19  2:21         ` Dmitry Osipenko
2019-07-19  6:09           ` Chanwoo Choi
2019-07-19  6:11             ` Chanwoo Choi
2019-07-19 17:52               ` Dmitry Osipenko
2019-07-24 11:17                 ` Chanwoo Choi
2019-07-24 11:19                   ` Chanwoo Choi
2019-07-07 22:33 ` [PATCH v4 21/24] PM / devfreq: tegra30: Synchronize average count on target's update Dmitry Osipenko
2019-07-18 10:15   ` Chanwoo Choi
2019-07-19  0:31     ` Dmitry Osipenko
2019-07-19  1:40       ` Chanwoo Choi
2019-07-19 16:46         ` Dmitry Osipenko [this message]
2019-07-07 22:33 ` [PATCH v4 22/24] PM / devfreq: tegra30: Include appropriate header Dmitry Osipenko
2019-07-18  9:58   ` Chanwoo Choi
2019-07-19  0:34     ` Dmitry Osipenko
2019-07-07 22:33 ` [PATCH v4 23/24] PM / devfreq: tegra30: Increase sampling period to 16ms Dmitry Osipenko
2019-07-18 10:00   ` Chanwoo Choi
2019-07-07 22:33 ` [PATCH v4 24/24] PM / devfreq: tegra20/30: Add Dmitry as a maintainer Dmitry Osipenko
2019-07-18  9:56   ` Chanwoo Choi

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