linux-kernel - [PATCH AUTOSEL 4.9 22/34] mfd: 88pm860x-i2c: switch to i2c_lock_bus(..., I2C_LOCK

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Date:   Sat, 15 Sep 2018 01:34:39 +0000
From:   Sasha Levin <Alexander.Levin@...rosoft.com>
To:     "stable@...r.kernel.org" <stable@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Peter Rosin <peda@...ntia.se>, Wolfram Sang <wsa@...-dreams.de>,
        Sasha Levin <Alexander.Levin@...rosoft.com>
Subject: [PATCH AUTOSEL 4.9 22/34] mfd: 88pm860x-i2c: switch to
 i2c_lock_bus(..., I2C_LOCK_SEGMENT)

From: Peter Rosin <peda@...ntia.se>

[ Upstream commit 8c8f74f327a76604a499fad8c54c15e1c0ee8051 ]

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@...ntia.se>
Acked-by: Lee Jones <lee.jones@...aro.org>
Signed-off-by: Wolfram Sang <wsa@...-dreams.de>
Signed-off-by: Sasha Levin <alexander.levin@...rosoft.com>
---
 drivers/mfd/88pm860x-i2c.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/mfd/88pm860x-i2c.c b/drivers/mfd/88pm860x-i2c.c
index 84e313107233..7b9052ea7413 100644
--- a/drivers/mfd/88pm860x-i2c.c
+++ b/drivers/mfd/88pm860x-i2c.c
@@ -146,14 +146,14 @@ int pm860x_page_reg_write(struct i2c_client *i2c, int reg,
 	unsigned char zero;
 	int ret;
 
-	i2c_lock_adapter(i2c->adapter);
+	i2c_lock_bus(i2c->adapter, I2C_LOCK_SEGMENT);
 	read_device(i2c, 0xFA, 0, &zero);
 	read_device(i2c, 0xFB, 0, &zero);
 	read_device(i2c, 0xFF, 0, &zero);
 	ret = write_device(i2c, reg, 1, &data);
 	read_device(i2c, 0xFE, 0, &zero);
 	read_device(i2c, 0xFC, 0, &zero);
-	i2c_unlock_adapter(i2c->adapter);
+	i2c_unlock_bus(i2c->adapter, I2C_LOCK_SEGMENT);
 	return ret;
 }
 EXPORT_SYMBOL(pm860x_page_reg_write);
@@ -164,14 +164,14 @@ int pm860x_page_bulk_read(struct i2c_client *i2c, int reg,
 	unsigned char zero = 0;
 	int ret;
 
-	i2c_lock_adapter(i2c->adapter);
+	i2c_lock_bus(i2c->adapter, I2C_LOCK_SEGMENT);
 	read_device(i2c, 0xfa, 0, &zero);
 	read_device(i2c, 0xfb, 0, &zero);
 	read_device(i2c, 0xff, 0, &zero);
 	ret = read_device(i2c, reg, count, buf);
 	read_device(i2c, 0xFE, 0, &zero);
 	read_device(i2c, 0xFC, 0, &zero);
-	i2c_unlock_adapter(i2c->adapter);
+	i2c_unlock_bus(i2c->adapter, I2C_LOCK_SEGMENT);
 	return ret;
 }
 EXPORT_SYMBOL(pm860x_page_bulk_read);
-- 
2.17.1