linux-kernel - [PATCH v2] PM / devfreq: tegra30: Make CPUFreq notifier to take into account boosting

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Message-Id: <20200402222448.8320-1-digetx@gmail.com>
Date:   Fri,  3 Apr 2020 01:24:48 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Jonathan Hunter <jonathanh@...dia.com>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] PM / devfreq: tegra30: Make CPUFreq notifier to take into account boosting

We're taking into account both HW memory-accesses + CPU activity based on
current CPU's frequency. For memory-accesses there is a kind of hysteresis
in a form of "boosting" which is managed by the tegra30-devfreq driver.
If current HW memory activity is higher than activity judged based of the
CPU's frequency, then there is no need to schedule cpufreq_update_work
because the result of the work will be a NO-OP. And thus,
tegra_actmon_cpufreq_contribution() should return 0, meaning that at the
moment CPU frequency doesn't contribute anything to the final decision
about required memory clock rate.

Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---

Changelog:

v2: - Made commit's message more detailed, which was requested by Chanwoo Choi
      in the review comment to v1.

    - This patch is now made to be standalone because there are no dependencies
      in regards to this change.

 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 28b2c7ca416e..dfc3ac93c584 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -420,7 +420,7 @@ tegra_actmon_cpufreq_contribution(struct tegra_devfreq *tegra,
 
 	static_cpu_emc_freq = actmon_cpu_to_emc_rate(tegra, cpu_freq);
 
-	if (dev_freq >= static_cpu_emc_freq)
+	if (dev_freq + actmon_dev->boost_freq >= static_cpu_emc_freq)
 		return 0;
 
 	return static_cpu_emc_freq;
-- 
2.25.1