linux-kernel - [PATCH 3/8 v2] i2c: i2c-bfin-twi: Break dead waiting loop if i2c device misbehaves.

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Message-ID: <1339575767-22985-3-git-send-email-sonic.adi@gmail.com>
Date:	Wed, 13 Jun 2012 16:22:42 +0800
From:	Sonic Zhang <sonic.adi@...il.com>
To:	Wolfram Sang <w.sang@...gutronix.de>,
	Ben Dooks <ben-linux@...ff.org>
CC:	<linux-i2c@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
	<uclinux-dist-devel@...ckfin.uclinux.org>,
	Sonic Zhang <sonic.zhang@...log.com>
Subject: [PATCH 3/8 v2] i2c: i2c-bfin-twi: Break dead waiting loop if i2c device misbehaves.

From: Sonic Zhang <sonic.zhang@...log.com>

Some fault i2c device may hold the sda/scl line and cause i2c driver
wait in the BUS busy loop. The I2C framework already retry the
transfer loop before timeout. Return -EAGAIN instead of pull BUSBUSY
in the other loop.

Signed-off-by: Sonic Zhang <sonic.zhang@...log.com>
---
 drivers/i2c/busses/i2c-bfin-twi.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
index dbe8fa0..a5ab454 100644
--- a/drivers/i2c/busses/i2c-bfin-twi.c
+++ b/drivers/i2c/busses/i2c-bfin-twi.c
@@ -307,8 +307,8 @@ static int bfin_twi_do_master_xfer(struct i2c_adapter *adap,
 	if (!(read_CONTROL(iface) & TWI_ENA))
 		return -ENXIO;
 
-	while (read_MASTER_STAT(iface) & BUSBUSY)
-		yield();
+	if (read_MASTER_STAT(iface) & BUSBUSY)
+		return -EAGAIN;
 
 	iface->pmsg = msgs;
 	iface->msg_num = num;
@@ -407,8 +407,8 @@ int bfin_twi_do_smbus_xfer(struct i2c_adapter *adap, u16 addr,
 	if (!(read_CONTROL(iface) & TWI_ENA))
 		return -ENXIO;
 
-	while (read_MASTER_STAT(iface) & BUSBUSY)
-		yield();
+	if (read_MASTER_STAT(iface) & BUSBUSY)
+		return -EAGAIN;
 
 	iface->writeNum = 0;
 	iface->readNum = 0;
-- 
1.7.0.4


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