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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 v1 04/11] PM / devfreq: tegra30: Drop write-barrier
Date: Mon, 24 Jun 2019 00:46:51 +0300
Message-ID: <20190623214658.11680-5-digetx@gmail.com> (raw)
In-Reply-To: <20190623214658.11680-1-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.

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 5e606ae3f238..4be7858c33bc 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 index

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-23 21:46 [PATCH v1 00/11] More improvements for Tegra30 devfreq driver Dmitry Osipenko
2019-06-23 21:46 ` [PATCH v1 01/11] PM / devfreq: tegra30: Change irq type to unsigned int Dmitry Osipenko
2019-06-23 21:46 ` [PATCH v1 02/11] PM / devfreq: tegra30: Keep interrupt disabled while governor is stopped Dmitry Osipenko
2019-06-23 21:46 ` [PATCH v1 03/11] PM / devfreq: tegra30: Handle possible round-rate error Dmitry Osipenko
2019-06-23 21:46 ` Dmitry Osipenko [this message]
2019-06-23 21:46 ` [PATCH v1 05/11] PM / devfreq: tegra30: Rework frequency management logic Dmitry Osipenko
2019-06-23 21:46 ` [PATCH v1 06/11] PM / devfreq: tegra30: Reset boosting on startup Dmitry Osipenko
2019-06-23 21:46 ` [PATCH v1 07/11] PM / devfreq: tegra30: Reset boosting if clock rate changed Dmitry Osipenko
2019-06-23 21:46 ` [PATCH v1 08/11] PM / devfreq: tegra30: Stop de-boosting once it's finished Dmitry Osipenko
2019-06-23 21:46 ` [PATCH v1 09/11] PM / devfreq: tegra30: Don't enable consecutive-down interrupt on startup Dmitry Osipenko
2019-06-23 21:46 ` [PATCH v1 10/11] PM / devfreq: tegra30: Add debug messages Dmitry Osipenko
2019-06-23 21:46 ` [PATCH v1 11/11] PM / devfreq: tegra30: Add Dmitry as maintainer Dmitry Osipenko
     [not found] ` <CGME20190623214841epcas5p161cceab51cb10d5146e57d49a696d5e5@epcms1p5>
2019-06-24  2:12   ` [PATCH v1 01/11] PM / devfreq: tegra30: Change irq type to unsigned int MyungJoo Ham

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