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From: Chanwoo Choi <cw00.choi@samsung.com>
To: Dmitry Osipenko <digetx@gmail.com>,
	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>
Cc: linux-pm@vger.kernel.org, linux-tegra@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 08/19] PM / devfreq: tegra30: Ensure that target freq won't overflow
Date: Tue, 20 Aug 2019 09:23:23 +0900
Message-ID: <c85dbd27-7536-9c51-19a2-fe1c2c6342b9@samsung.com> (raw)
In-Reply-To: <20190811212315.12689-9-digetx@gmail.com>

On 19. 8. 12. 오전 6:23, Dmitry Osipenko wrote:
> We already had few integer overflow bugs, let's limit the freq for
> consistency.
> 
> Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
> ---
>  drivers/devfreq/tegra30-devfreq.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 70dce58212a4..ca499368ee81 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -430,7 +430,7 @@ static unsigned long actmon_update_target(struct tegra_devfreq *tegra,
>  	target_freq = dev->avg_count / ACTMON_SAMPLING_PERIOD + dev->boost_freq;
>  	target_freq = tegra_actmon_account_cpu_freq(tegra, dev, target_freq);
>  
> -	return target_freq;
> +	return min(target_freq, tegra->max_freq);

Once again, did you meet this case sometimes?

Usually, we can prevent the overflow of target_freq
when calculating the target frequency or this style.

I think that if the overflow of target frequency happen frequently,
it might have the problem of calculation way. 

>  }
>  
>  static irqreturn_t actmon_thread_isr(int irq, void *data)
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics

  reply index

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-11 21:22 [PATCH v6 00/19] More improvements for Tegra30 devfreq driver Dmitry Osipenko
2019-08-11 21:22 ` [PATCH v6 01/19] PM / devfreq: tegra30: Change irq type to unsigned int Dmitry Osipenko
2019-08-11 21:22 ` [PATCH v6 02/19] PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped Dmitry Osipenko
2019-08-20  0:02   ` Chanwoo Choi
2019-08-11 21:22 ` [PATCH v6 03/19] PM / devfreq: tegra30: Handle possible round-rate error Dmitry Osipenko
2019-08-20  0:06   ` Chanwoo Choi
2019-08-11 21:23 ` [PATCH v6 04/19] PM / devfreq: tegra30: Drop write-barrier Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 05/19] PM / devfreq: tegra30: Set up watermarks properly Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 06/19] PM / devfreq: tegra30: Tune up boosting thresholds Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 07/19] PM / devfreq: tegra30: Fix integer overflow on CPU's freq max out Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 08/19] PM / devfreq: tegra30: Ensure that target freq won't overflow Dmitry Osipenko
2019-08-20  0:23   ` Chanwoo Choi [this message]
2019-08-20 23:19     ` Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 09/19] PM / devfreq: tegra30: Use kHz units uniformly in the code Dmitry Osipenko
2019-10-01 23:29   ` Chanwoo Choi
2019-10-02 18:26     ` Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 10/19] PM / devfreq: tegra30: Reduce unnecessary interrupts activity Dmitry Osipenko
2019-10-01 23:35   ` Chanwoo Choi
2019-10-02 18:40     ` Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 11/19] PM / devfreq: tegra30: Use CPUFreq notifier Dmitry Osipenko
2019-10-02  0:02   ` Chanwoo Choi
2019-10-02 14:06     ` Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 12/19] PM / devfreq: tegra30: Move clk-notifier's registration to governor's start Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 13/19] PM / devfreq: tegra30: Reset boosting on startup Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 14/19] PM / devfreq: tegra30: Don't enable consecutive-down interrupt " Dmitry Osipenko
2019-10-02  0:04   ` Chanwoo Choi
2019-08-11 21:23 ` [PATCH v6 15/19] PM / devfreq: tegra30: Constify structs Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 16/19] PM / devfreq: tegra30: Include appropriate header Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 17/19] PM / devfreq: tegra30: Increase sampling period to 16ms Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 18/19] PM / devfreq: tegra30: Support variable polling interval Dmitry Osipenko
2019-10-02  0:18   ` Chanwoo Choi
2019-10-02 15:27     ` Dmitry Osipenko
2019-08-11 21:23 ` [PATCH v6 19/19] PM / devfreq: tegra20/30: Add Dmitry as a maintainer Dmitry Osipenko
2019-10-01 21:15 ` [PATCH v6 00/19] More improvements for Tegra30 devfreq driver Dmitry Osipenko
2019-10-02  0:25   ` Chanwoo Choi
2019-10-02 13:54     ` Dmitry Osipenko
2019-10-05 16:29       ` Peter Geis

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