linux-kernel - [PATCH AUTOSEL 5.2 39/70] pinctrl: tegra: Fix write barrier placement in pmx

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Date:   Tue, 24 Sep 2019 12:45:18 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Sowjanya Komatineni <skomatineni@...dia.com>,
        Thierry Reding <treding@...dia.com>,
        Dmitry Osipenko <digetx@...il.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        Sasha Levin <sashal@...nel.org>, linux-gpio@...r.kernel.org,
        linux-tegra@...r.kernel.org
Subject: [PATCH AUTOSEL 5.2 39/70] pinctrl: tegra: Fix write barrier placement in pmx_writel

From: Sowjanya Komatineni <skomatineni@...dia.com>

[ Upstream commit c2cf351eba2ff6002ce8eb178452219d2521e38e ]

pmx_writel uses writel which inserts write barrier before the
register write.

This patch has fix to replace writel with writel_relaxed followed
by a readback and memory barrier to ensure write operation is
completed for successful pinctrl change.

Acked-by: Thierry Reding <treding@...dia.com>
Reviewed-by: Dmitry Osipenko <digetx@...il.com>
Signed-off-by: Sowjanya Komatineni <skomatineni@...dia.com>
Link: https://lore.kernel.org/r/1565984527-5272-2-git-send-email-skomatineni@nvidia.com
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/pinctrl/tegra/pinctrl-tegra.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/pinctrl/tegra/pinctrl-tegra.c b/drivers/pinctrl/tegra/pinctrl-tegra.c
index abcfbad94f00e..849c3b34e887c 100644
--- a/drivers/pinctrl/tegra/pinctrl-tegra.c
+++ b/drivers/pinctrl/tegra/pinctrl-tegra.c
@@ -32,7 +32,9 @@ static inline u32 pmx_readl(struct tegra_pmx *pmx, u32 bank, u32 reg)
 
 static inline void pmx_writel(struct tegra_pmx *pmx, u32 val, u32 bank, u32 reg)
 {
-	writel(val, pmx->regs[bank] + reg);
+	writel_relaxed(val, pmx->regs[bank] + reg);
+	/* make sure pinmux register write completed */
+	pmx_readl(pmx, bank, reg);
 }
 
 static int tegra_pinctrl_get_groups_count(struct pinctrl_dev *pctldev)
-- 
2.20.1