From: Clifford Wolf <clifford@xxxxxxxxxxx>
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 <clifford@xxxxxxxxxxx>
Cc: Jean Delvare <khali@xxxxxxxxxxxx>
Cc: Ben Dooks <ben-linux@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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:
_
--
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