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From: Chanwoo Choi <cw00.choi@samsung.com>
To: Dmitry Osipenko <digetx@gmail.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 11/24] PM / devfreq: tegra30: Add debug messages
Date: Fri, 19 Jul 2019 10:22:37 +0900
Message-ID: <a5e0c217-280f-a420-4604-3872a17f5c96@samsung.com> (raw)
In-Reply-To: <20190719041357.0a80a2dc@dimatab>

On 19. 7. 19. 오전 10:13, Dmitry Osipenko wrote:
> В Thu, 18 Jul 2019 18:07:05 +0900
> Chanwoo Choi <cw00.choi@samsung.com> пишет:
> 
>> On 19. 7. 18. 오전 12:46, Dmitry Osipenko wrote:
>>> 17.07.2019 9:45, Chanwoo Choi пишет:  
>>>> On 19. 7. 16. 오후 10:26, Dmitry Osipenko wrote:  
>>>>> 16.07.2019 15:23, Chanwoo Choi пишет:  
>>>>>> Hi Dmitry,
>>>>>>
>>>>>> Usually, the kernel log print for all users
>>>>>> such as changing the frequency, fail or success.
>>>>>>
>>>>>> But, if the log just show the register dump,
>>>>>> it is not useful for all users. It is just used
>>>>>> for only specific developer.
>>>>>>
>>>>>> I recommend that you better to add more exception handling
>>>>>> code on many points instead of just showing the register dump.  
>>>>>
>>>>> The debug messages are not users, but for developers. Yes, I
>>>>> primarily made the debugging to be useful for myself and will be
>>>>> happy to change the way debugging is done if there will be any
>>>>> other active developer for this driver. The registers dump is
>>>>> more than enough in order to understand what's going on, I don't
>>>>> see any real need to change anything here for now.  
>>>>
>>>> Basically, we have to develop code and add the log for anyone.
>>>> As you commented, even if there are no other developer, we never
>>>> guarantee this assumption forever. And also, if added debug message
>>>> for only you, you can add them when testing it temporarily.
>>>>
>>>> If you want to add the just register dump log for you,
>>>> I can't agree. Once again, I hope that anyone understand
>>>> the meaning of debug message as much possible as.
>>>>  
>>>
>>> The registers dump should be good for everyone because it's a
>>> self-explanatory information for anyone who is familiar with the
>>> hardware. I don't think there is a need for anything else than what
>>> is proposed in this patch, at least for now. I also simply don't
>>> see any other better way to debug the state of this particular
>>> hardware, again this logging is for the driver developers and not
>>> for users.
>>>
>>> Initially, I was temporarily adding the debug messages. Now they are
>>> pretty much mandatory for verifying that driver is working
>>> properly. And of course the debugging messages got into the shape
>>> of this patch after several iterations of refinements. So again, I
>>> suppose that this should be good enough for everyone who is
>>> familiar with the hardware. And of course I'm open to the
>>> constructive suggestions, the debugging aid is not an ABI and could
>>> be changed/improved at any time.
>>>
>>> You're suggesting to break down the debugging into several smaller
>>> pieces, but I'm finding that as not a constructive suggestion
>>> because the information about the full hardware state is actually
>>> necessary for the productive debugging.
>>>
>>>   
>>
>> Sorry for that as I saie, I cannot agree this patch. In my case,
>> I don't understand what is meaning of register dump of this patch.
>> I knew that just register dump are useful for real developer.
> 
> It's not only a registers dump, as you may see there is also a dump of
> other properties like boosting value, OPPs selection and etc.
> 
> It looks to me that you're also missing important detail that debug
> messages are compiled out unless DEBUG is defined for the drivers
> build. So in order to get the debug message a user shall explicitly add
> #define DEBUG macro to the code or enable debug messages globally in
> the kernel's config. There is also an option for dynamic debug messages
> in the kernel, but it doesn't matter now because all these messages are
> turned into tracepoints later in the patch #17.


Right. But, this patch could not the split up between register dump and others.
As I said repeatly, I hope to add the log that anyone can understand. 


> 
>> If you want to show the register dump, you better to add some feature
>> with debugfs for devfreq framework in order to read the register dump.
>> As I knew, sound framework (alsa) has the similar feature for checking
>> the register dump.
>>
> 
> The intent was to have an option for dynamic debugging of the driver and
> initially debug messages were good enough, but then it became not enough
> and hence the debug messages were turned into tracepoints in the patch
> #17. Would it be acceptable to squash this patch and #17?
> 
> 
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

  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 [this message]
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
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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