linux-kernel - [PATCH 4.4 007/135] i2c: pxa: clear all master action bits in i2c_pxa_stop

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Message-Id: <20200629155309.2495516-8-sashal@kernel.org>
Date:   Mon, 29 Jun 2020 11:51:01 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Russell King <rmk+kernel@...linux.org.uk>,
        Wolfram Sang <wsa@...nel.org>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 007/135] i2c: pxa: clear all master action bits in i2c_pxa_stop_message()

From: Russell King <rmk+kernel@...linux.org.uk>

[ Upstream commit e81c979f4e071d516aa27cf5a0c3939da00dc1ca ]

If we timeout during a message transfer, the control register may
contain bits that cause an action to be set. Read-modify-writing the
register leaving these bits set may trigger the hardware to attempt
one of these actions unintentionally.

Always clear these bits when cleaning up after a message or after
a timeout.

Signed-off-by: Russell King <rmk+kernel@...linux.org.uk>
Signed-off-by: Wolfram Sang <wsa@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/i2c/busses/i2c-pxa.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 0d351954db02b..3264b50311ff0 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -691,11 +691,9 @@ static inline void i2c_pxa_stop_message(struct pxa_i2c *i2c)
 {
 	u32 icr;
 
-	/*
-	 * Clear the STOP and ACK flags
-	 */
+	/* Clear the START, STOP, ACK, TB and MA flags */
 	icr = readl(_ICR(i2c));
-	icr &= ~(ICR_STOP | ICR_ACKNAK);
+	icr &= ~(ICR_START | ICR_STOP | ICR_ACKNAK | ICR_TB | ICR_MA);
 	writel(icr, _ICR(i2c));
 }
 
-- 
2.25.1