linux-kernel - [PATCH v9 11/17] arm: tegra20/30: cpuidle: Remove unnecessary memory barrier

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Date:   Thu, 13 Feb 2020 02:51:28 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Thierry Reding <thierry.reding@...il.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Peter De Schrijver <pdeschrijver@...dia.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Michał Mirosław <mirq-linux@...e.qmqm.pl>,
        Jasper Korten <jja2000@...il.com>,
        David Heidelberg <david@...t.cz>,
        Peter Geis <pgwipeout@...il.com>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v9 11/17] arm: tegra20/30: cpuidle: Remove unnecessary memory barrier

There is no good justification for smp_rmb() after returning from LP2
because there are no memory operations that require SMP synchronization.
Thus remove the confusing barrier.

Acked-by: Peter De Schrijver <pdeschrijver@...dia.com>
Tested-by: Peter Geis <pgwipeout@...il.com>
Tested-by: Jasper Korten <jja2000@...il.com>
Tested-by: David Heidelberg <david@...t.cz>
Signed-off-by: Dmitry Osipenko <digetx@...il.com>
---
 arch/arm/mach-tegra/cpuidle-tegra20.c | 2 --
 arch/arm/mach-tegra/cpuidle-tegra30.c | 2 --
 2 files changed, 4 deletions(-)

diff --git a/arch/arm/mach-tegra/cpuidle-tegra20.c b/arch/arm/mach-tegra/cpuidle-tegra20.c
index ccb8b0aa6c46..f8f14c0b79ff 100644
--- a/arch/arm/mach-tegra/cpuidle-tegra20.c
+++ b/arch/arm/mach-tegra/cpuidle-tegra20.c
@@ -194,8 +194,6 @@ static int tegra20_idle_lp2_coupled(struct cpuidle_device *dev,
 
 	local_fiq_enable();
 
-	smp_rmb();
-
 	return entered_lp2 ? index : 0;
 }
 #endif
diff --git a/arch/arm/mach-tegra/cpuidle-tegra30.c b/arch/arm/mach-tegra/cpuidle-tegra30.c
index a4f0add46a27..80ae64bcdf50 100644
--- a/arch/arm/mach-tegra/cpuidle-tegra30.c
+++ b/arch/arm/mach-tegra/cpuidle-tegra30.c
@@ -113,8 +113,6 @@ static int tegra30_idle_lp2(struct cpuidle_device *dev,
 
 	local_fiq_enable();
 
-	smp_rmb();
-
 	return (entered_lp2) ? index : 0;
 }
 #endif
-- 
2.24.0