i2c: Retry automatically on arbitration loss
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>
diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index dfd7bc8..635c488 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1022,7 +1022,8 @@
*/
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:
*
@@ -1060,7 +1061,15 @@
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);
return ret;
@@ -1995,14 +2004,27 @@
char read_write, u8 command, int protocol,
union i2c_smbus_data *data)
{
+ unsigned long orig_jiffies;
+ int try;
s32 res;
flags &= I2C_M_TEN | I2C_CLIENT_PEC;
if (adapter->algo->smbus_xfer) {
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);
} else
res = i2c_smbus_xfer_emulated(adapter,addr,flags,read_write,