From: Clifford Wolf <[email protected]> Simply retry on arbitration lost until xfer is successfull, 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]> Signed-off-by: Andrew Morton <[email protected]> --- drivers/i2c/busses/i2c-mpc.c | 22 ++++++++++++++-------- 1 file changed, 14 insertions(+), 8 deletions(-) diff -puN drivers/i2c/busses/i2c-mpc.c~i2c-fix-i2c-mpc-driver-for-multi-master-i2c-busses drivers/i2c/busses/i2c-mpc.c --- a/drivers/i2c/busses/i2c-mpc.c~i2c-fix-i2c-mpc-driver-for-multi-master-i2c-busses +++ a/drivers/i2c/busses/i2c-mpc.c @@ -134,13 +134,13 @@ static int i2c_wait(struct mpc_i2c *i2c, if (result < 0) return result; - if (!(x & CSR_MCF)) { - pr_debug("I2C: unfinished\n"); - return -EIO; - } - if (x & CSR_MAL) { pr_debug("I2C: MAL\n"); + return -EAGAIN; + } + + if (!(x & CSR_MCF)) { + pr_debug("I2C: unfinished\n"); return -EIO; } @@ -257,11 +257,11 @@ static int mpc_read(struct mpc_i2c *i2c, static int mpc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) { struct i2c_msg *pmsg; - int i; - int ret = 0; + int i, ret; unsigned long orig_jiffies = jiffies; struct mpc_i2c *i2c = i2c_get_adapdata(adap); +restart: mpc_i2c_start(i2c); /* Allow bus up to 1s to become not busy */ @@ -281,7 +281,7 @@ static int mpc_xfer(struct i2c_adapter * schedule(); } - for (i = 0; ret >= 0 && i < num; i++) { + for (i = 0, ret = 0; ret >= 0 && i < num; i++) { pmsg = &msgs[i]; pr_debug("Doing %s %d bytes to 0x%02x - %d of %d messages\n", pmsg->flags & I2C_M_RD ? "read" : "write", @@ -292,7 +292,13 @@ static int mpc_xfer(struct i2c_adapter * else ret = mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, i); + if (ret == -EAGAIN) { + pr_debug("Lost i2c arbitration -> retry.\n"); + mpc_i2c_stop(i2c); + goto restart; + } } + mpc_i2c_stop(i2c); return (ret < 0) ? ret : num; } _ -- 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
