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Commit 66b650f0 authored by Clifford Wolf's avatar Clifford Wolf Committed by Jean Delvare
Browse files

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: default avatarClifford Wolf <clifford@clifford.at>
Signed-off-by: default avatarJean Delvare <khali@linux-fr.org>
parent 1cf92b45

drivers/i2c/i2c-core.c

+26 −4
Original line number Diff line number Diff line
@@ -1022,7 +1022,8 @@ module_exit(i2c_exit); 
 */

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 @@ int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) 
			mutex_lock_nested(&adap->bus_lock, adap->level);

		}



		/* 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 @@ s32 i2c_smbus_xfer(struct i2c_adapter *adapter, u16 addr, unsigned short flags, 
		   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,