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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Peter Rosin <peda@axentia.se>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        Wolfram Sang <wsa@the-dreams.de>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 093/111] input: rohm_bu21023: switch to i2c_lock_bus(..., I2C_LOCK_SEGMENT)
Date:   Mon, 24 Sep 2018 13:53:00 +0200
Message-Id: <20180924113114.130661128@linuxfoundation.org>
In-Reply-To: <20180924113103.337261320@linuxfoundation.org>
References: <20180924113103.337261320@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Peter Rosin <peda@axentia.se>

[ Upstream commit 193c2a07cfaacb9249ab0e3d34bce32490879355 ]

Locking the root adapter for __i2c_transfer will deadlock if the
device sits behind a mux-locked I2C mux. Switch to the finer-grained
i2c_lock_bus with the I2C_LOCK_SEGMENT flag. If the device does not
sit behind a mux-locked mux, the two locking variants are equivalent.

Signed-off-by: Peter Rosin <peda@axentia.se>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/input/touchscreen/rohm_bu21023.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/input/touchscreen/rohm_bu21023.c
+++ b/drivers/input/touchscreen/rohm_bu21023.c
@@ -304,7 +304,7 @@ static int rohm_i2c_burst_read(struct i2
 	msg[1].len = len;
 	msg[1].buf = buf;
 
-	i2c_lock_adapter(adap);
+	i2c_lock_bus(adap, I2C_LOCK_SEGMENT);
 
 	for (i = 0; i < 2; i++) {
 		if (__i2c_transfer(adap, &msg[i], 1) < 0) {
@@ -313,7 +313,7 @@ static int rohm_i2c_burst_read(struct i2
 		}
 	}
 
-	i2c_unlock_adapter(adap);
+	i2c_unlock_bus(adap, I2C_LOCK_SEGMENT);
 
 	return ret;
 }