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From: Dmitry Osipenko <digetx@gmail.com>
To: Thierry Reding <thierry.reding@gmail.com>,
	MyungJoo Ham <myungjoo.ham@samsung.com>,
	Kyungmin Park <kyungmin.park@samsung.com>,
	Chanwoo Choi <cw00.choi@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: [PATCH v5 04/20] PM / devfreq: tegra30: Drop write-barrier
Date: Tue, 30 Jul 2019 19:22:20 +0300	[thread overview]
Message-ID: <20190730162236.6063-5-digetx@gmail.com> (raw)
In-Reply-To: <20190730162236.6063-1-digetx@gmail.com>

There is no need in a write-barrier now, given that interrupt masking is
handled by CPU's GIC now. Hence we know exactly that interrupt won't fire
after stopping the devfreq's governor. In other cases we don't care about
potential buffering of the writes to hardware and thus there is no need to
stall CPU.

Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 drivers/devfreq/tegra30-devfreq.c | 14 --------------
 1 file changed, 14 deletions(-)

diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
index bfee9d43de1e..ee14bf534c0d 100644
--- a/drivers/devfreq/tegra30-devfreq.c
+++ b/drivers/devfreq/tegra30-devfreq.c
@@ -230,12 +230,6 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
 		      ACTMON_DEV_LOWER_WMARK);
 }
 
-static void actmon_write_barrier(struct tegra_devfreq *tegra)
-{
-	/* ensure the update has reached the ACTMON */
-	readl(tegra->regs + ACTMON_GLB_STATUS);
-}
-
 static void actmon_isr_device(struct tegra_devfreq *tegra,
 			      struct tegra_devfreq_device *dev)
 {
@@ -287,8 +281,6 @@ static void actmon_isr_device(struct tegra_devfreq *tegra,
 	device_writel(dev, dev_ctrl, ACTMON_DEV_CTRL);
 
 	device_writel(dev, ACTMON_INTR_STATUS_CLEAR, ACTMON_DEV_INTR_STATUS);
-
-	actmon_write_barrier(tegra);
 }
 
 static unsigned long actmon_cpu_to_emc_rate(struct tegra_devfreq *tegra,
@@ -376,8 +368,6 @@ static int tegra_actmon_rate_notify_cb(struct notifier_block *nb,
 		tegra_devfreq_update_wmark(tegra, dev);
 	}
 
-	actmon_write_barrier(tegra);
-
 	return NOTIFY_OK;
 }
 
@@ -423,8 +413,6 @@ static void tegra_actmon_start(struct tegra_devfreq *tegra)
 	for (i = 0; i < ARRAY_SIZE(tegra->devices); i++)
 		tegra_actmon_configure_device(tegra, &tegra->devices[i]);
 
-	actmon_write_barrier(tegra);
-
 	enable_irq(tegra->irq);
 }
 
@@ -439,8 +427,6 @@ static void tegra_actmon_stop(struct tegra_devfreq *tegra)
 		device_writel(&tegra->devices[i], ACTMON_INTR_STATUS_CLEAR,
 			      ACTMON_DEV_INTR_STATUS);
 	}
-
-	actmon_write_barrier(tegra);
 }
 
 static int tegra_devfreq_target(struct device *dev, unsigned long *freq,
-- 
2.22.0


  parent reply	other threads:[~2019-07-30 16:32 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-30 16:22 [PATCH v5 00/20] More improvements for Tegra30 devfreq driver Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 01/20] PM / devfreq: tegra30: Change irq type to unsigned int Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 02/20] PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 03/20] PM / devfreq: tegra30: Handle possible round-rate error Dmitry Osipenko
2019-07-30 16:22 ` Dmitry Osipenko [this message]
2019-07-30 16:22 ` [PATCH v5 05/20] PM / devfreq: tegra30: Set up watermarks properly Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 06/20] PM / devfreq: tegra30: Tune up boosting thresholds Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 07/20] PM / devfreq: tegra30: Fix integer overflow on CPU's freq max out Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 08/20] PM / devfreq: tegra30: Ensure that target freq won't overflow Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 09/20] PM / devfreq: tegra30: Use kHz units uniformly in the code Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 10/20] PM / devfreq: tegra30: Reduce unnecessary interrupts activity Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 11/20] PM / devfreq: tegra30: Use CPUFreq notifier Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 12/20] PM / devfreq: tegra30: Move clk-notifier's registration to governor's start Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 13/20] PM / devfreq: tegra30: Reset boosting on startup Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 14/20] PM / devfreq: tegra30: Don't enable consecutive-down interrupt " Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 15/20] PM / devfreq: tegra30: Constify structs Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 16/20] PM / devfreq: tegra30: Include appropriate header Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 17/20] PM / devfreq: tegra30: Increase sampling period to 16ms Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 18/20] PM / devfreq: tegra30: Define ACTMON_DEV_CTRL_STOP Dmitry Osipenko
2019-07-31  0:37   ` Chanwoo Choi
2019-07-31 10:55     ` Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 19/20] PM / devfreq: tegra30: Support variable polling interval Dmitry Osipenko
2019-07-30 16:22 ` [PATCH v5 20/20] PM / devfreq: tegra20/30: Add Dmitry as a maintainer Dmitry Osipenko

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