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i2c: Retry automatically on arbitration loss

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Some small changes in i2c core to retry i2c xfers until either the
maximum number of retries or the timeout is hit.

Signed-off-by: Clifford Wolf <clifford@clifford.at>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
This commit is contained in:
Clifford Wolf 2009-06-15 18:01:46 +02:00 • committed by Jean Delvare
parent 1cf92b453a
commit 66b650f045
1 changed files with 26 additions and 4 deletions
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30
drivers/i2c/i2c-core.c
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@ -1022,7 +1022,8 @@ module_exit(i2c_exit);
*/ */
int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{ {
int ret; unsigned long orig_jiffies;
int ret, try;
/* REVISIT the fault reporting model here is weak: /* REVISIT the fault reporting model here is weak:
* *
@ -1060,7 +1061,15 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
mutex_lock_nested(&adap->bus_lock, adap->level); mutex_lock_nested(&adap->bus_lock, adap->level);
} }
ret = adap->algo->master_xfer(adap,msgs,num); /* Retry automatically on arbitration loss */
orig_jiffies = jiffies;
for (ret = 0, try = 0; try <= adap->retries; try++) {
ret = adap->algo->master_xfer(adap, msgs, num);
if (ret != -EAGAIN)
break;
if (time_after(jiffies, orig_jiffies + adap->timeout))
break;
}
mutex_unlock(&adap->bus_lock); mutex_unlock(&adap->bus_lock);
return ret; return ret;
@ -1995,14 +2004,27 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags,
char read_write, u8 command, int protocol, char read_write, u8 command, int protocol,
union i2c_smbus_data *data) union i2c_smbus_data *data)
{ {
unsigned long orig_jiffies;
int try;
s32 res; s32 res;
flags &= I2C_M_TEN | I2C_CLIENT_PEC; flags &= I2C_M_TEN | I2C_CLIENT_PEC;
if (adapter->algo->smbus_xfer) { if (adapter->algo->smbus_xfer) {
mutex_lock(&adapter->bus_lock); mutex_lock(&adapter->bus_lock);
res = adapter->algo->smbus_xfer(adapter,addr,flags,read_write,
command, protocol, data); /* Retry automatically on arbitration loss */
orig_jiffies = jiffies;
for (res = 0, try = 0; try <= adapter->retries; try++) {
res = adapter->algo->smbus_xfer(adapter, addr, flags,
read_write, command,
protocol, data);
if (res != -EAGAIN)
break;
if (time_after(jiffies,
orig_jiffies + adapter->timeout))
break;
}
mutex_unlock(&adapter->bus_lock); mutex_unlock(&adapter->bus_lock);
} else } else
res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write, res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,