From: Clifford Wolf <[email protected]> Retry on arbitration lost until xfer is successful, a non-arbitration-lost error is triggered or the 1s timeout is hit.
Tested with a freescale MPC8349E host cpu. Signed-off-by: Clifford Wolf <[email protected]> Cc: Jean Delvare <[email protected]> Cc: Ben Dooks <[email protected]> Signed-off-by: Andrew Morton <[email protected]> --- drivers/i2c/busses/i2c-mpc.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff -puN drivers/i2c/busses/i2c-mpc.c~i2c-incremental-i2c-mpc-driver-fix-for-multi-master-i2c-busses drivers/i2c/busses/i2c-mpc.c --- a/drivers/i2c/busses/i2c-mpc.c~i2c-incremental-i2c-mpc-driver-fix-for-multi-master-i2c-busses +++ a/drivers/i2c/busses/i2c-mpc.c @@ -106,7 +106,7 @@ static int i2c_wait(struct mpc_i2c *i2c, schedule(); if (time_after(jiffies, orig_jiffies + timeout)) { pr_debug("I2C: timeout\n"); - writeccr(i2c, 0); + writeccr(i2c, CCR_MEN); result = -EIO; break; } @@ -120,10 +120,10 @@ static int i2c_wait(struct mpc_i2c *i2c, if (unlikely(result < 0)) { pr_debug("I2C: wait interrupted\n"); - writeccr(i2c, 0); + writeccr(i2c, CCR_MEN); } else if (unlikely(!(i2c->interrupt & CSR_MIF))) { pr_debug("I2C: wait timeout\n"); - writeccr(i2c, 0); + writeccr(i2c, CCR_MEN); result = -ETIMEDOUT; } @@ -268,7 +268,7 @@ static int mpc_xfer(struct i2c_adapter * while (readb(i2c->base + MPC_I2C_SR) & CSR_MBB) { if (signal_pending(current)) { pr_debug("I2C: Interrupted\n"); - writeccr(i2c, 0); + writeccr(i2c, CCR_MEN); return -EINTR; } if (time_after(jiffies, orig_jiffies + HZ)) { @@ -364,6 +364,15 @@ static int __devinit fsl_i2c_probe(struc } of_register_i2c_devices(&i2c->adap, op->node); + /* Make sure the adapter is already in master mode some time before + * the first xfer to make sure arbitration control had enough time + * to monitor the bus. The CCR_MEN flag should never be cleared without + * makeing sure there is some delay between setting it again and + * starting the first transfer.. + */ + writeccr(i2c, CCR_MEN); + udelay(100); + return result; fail_add: _ -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
