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Subject[PATCH 3/8] i2c: i2c-bfin-twi: Break dead waiting loop if i2c device misbehaves.
Date
From: Sonic Zhang <sonic.zhang@analog.com>

Some fault i2c device may hold the sda/scl line and cause i2c driver
wait in the BUS busy loop. This patch breaks this potential dead
loop.

Signed-off-by: Sonic Zhang <sonic.zhang@analog.com>

git-svn-id: svn://localhost/svn/linux-kernel/trunk@9291 526b6c2d-f592-4532-a319-5dd88ccb003d
---
drivers/i2c/busses/i2c-bfin-twi.c | 14 ++++++++++++--
1 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-bfin-twi.c b/drivers/i2c/busses/i2c-bfin-twi.c
index 376e331..4abaf59 100644
--- a/drivers/i2c/busses/i2c-bfin-twi.c
+++ b/drivers/i2c/busses/i2c-bfin-twi.c
@@ -294,6 +294,8 @@ static irqreturn_t bfin_twi_interrupt_entry(int irq, void *dev_id)
return IRQ_HANDLED;
}

+#define BFIN_TWI_BUSY_TIMEOUT 1000
+
/*
* One i2c master transfer
*/
@@ -303,12 +305,16 @@ static int bfin_twi_do_master_xfer(struct i2c_adapter *adap,
struct bfin_twi_iface *iface = adap->algo_data;
struct i2c_msg *pmsg;
int rc = 0;
+ unsigned int busy_timeout = BFIN_TWI_BUSY_TIMEOUT;

if (!(read_CONTROL(iface) & TWI_ENA))
return -ENXIO;

- while (read_MASTER_STAT(iface) & BUSBUSY)
+ while (read_MASTER_STAT(iface) & BUSBUSY) {
+ if (--busy_timeout == 0)
+ return -EBUSY;
yield();
+ }

iface->pmsg = msgs;
iface->msg_num = num;
@@ -403,12 +409,16 @@ int bfin_twi_do_smbus_xfer(struct i2c_adapter *adap, u16 addr,
{
struct bfin_twi_iface *iface = adap->algo_data;
int rc = 0;
+ unsigned int busy_timeout = BFIN_TWI_BUSY_TIMEOUT;

if (!(read_CONTROL(iface) & TWI_ENA))
return -ENXIO;

- while (read_MASTER_STAT(iface) & BUSBUSY)
+ while (read_MASTER_STAT(iface) & BUSBUSY) {
+ if (--busy_timeout == 0)
+ return -EBUSY;
yield();
+ }

iface->writeNum = 0;
iface->readNum = 0;
--
1.7.0.4



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