linux-kernel - Re: [PATCH v4 10/24] PM / devfreq: tegra30: Don't enable consecutive-down interrupt on startup

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Message-ID: <54ad7bb8-1ffe-50bc-9003-acc02b1b6f9d@gmail.com>
Date:   Tue, 16 Jul 2019 18:17:18 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Chanwoo Choi <cw00.choi@...sung.com>,
        Thierry Reding <thierry.reding@...il.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 10/24] PM / devfreq: tegra30: Don't enable
 consecutive-down interrupt on startup

16.07.2019 15:17, Chanwoo Choi пишет:
> Hi Dmitry,
> 
> On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote:
>> The consecutive-down event tells that we should perform frequency
>> de-boosting, but boosting is in a reset state on start and hence the
>> event won't do anything useful for us and it will be just a dummy
>> interrupt request.
>>
>> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
>> ---
>>  drivers/devfreq/tegra30-devfreq.c | 1 -
>>  1 file changed, 1 deletion(-)
>>
>> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
>> index 32fe95458ee7..878c9396bb8c 100644
>> --- a/drivers/devfreq/tegra30-devfreq.c
>> +++ b/drivers/devfreq/tegra30-devfreq.c
>> @@ -558,7 +558,6 @@ static void tegra_actmon_configure_device(struct tegra_devfreq *tegra,
>>  		<< ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_NUM_SHIFT;
>>  	val |= ACTMON_DEV_CTRL_AVG_ABOVE_WMARK_EN;
>>  	val |= ACTMON_DEV_CTRL_AVG_BELOW_WMARK_EN;
>> -	val |= ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN;
>>  	val |= ACTMON_DEV_CTRL_CONSECUTIVE_ABOVE_WMARK_EN;
>>  	val |= ACTMON_DEV_CTRL_ENB;
>>  
>>
> 
> Maybe, I think that better to review it by Thierry.
> I'm not sure it is right or not because it depend on h/w.
> 

The CONSECUTIVE_LOWER interrupts are generated if
ACTMON_DEV_CTRL_CONSECUTIVE_BELOW_WMARK_EN is enabled and ISR enables
the BELOW_WMARK_EN bit once CONSECUTIVE_UPPER event is received. The
CONSECUTIVE events are used in for the frequency boosting logic and
there is no boosting on start, hence the CONSECUTIVE_LOWER event isn't
needed on start as well. Hope this helps.