linux-kernel - [PATCH v4 03/16] PM / devfreq: tegra: Replace write memory barrier with the read barrier

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Date:   Thu,  2 May 2019 02:38:02 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v4 03/16] PM / devfreq: tegra: Replace write memory barrier with the read barrier

The write memory barrier isn't needed because the BUS buffer is flushed
by read after write that happens after the removed wmb(), we will also
use readl() instead of the relaxed version to ensure that read is indeed
completed.

Reviewed-by: Chanwoo Choi <cw00.choi@...sung.com>
Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 drivers/devfreq/tegra-devfreq.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/drivers/devfreq/tegra-devfreq.c b/drivers/devfreq/tegra-devfreq.c
index f7378a42d184..7d7b9a5895b2 100644
--- a/drivers/devfreq/tegra-devfreq.c
+++ b/drivers/devfreq/tegra-devfreq.c
@@ -243,8 +243,7 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
 static void actmon_write_barrier(struct tegra_devfreq *tegra)
 {
 	/* ensure the update has reached the ACTMON */
-	wmb();
-	actmon_readl(tegra, ACTMON_GLB_STATUS);
+	readl(tegra->regs + ACTMON_GLB_STATUS);
 }
 
 static void actmon_isr_device(struct tegra_devfreq *tegra,
-- 
2.21.0