From a16d8aa4726a944ffc1616689ae34ff6a902faba Mon Sep 17 00:00:00 2001 From: Sachin Surendran Date: Mon, 26 Nov 2012 11:20:01 +1300 Subject: [PATCH] i2c-cpm: Fix to takeback i2c bus master-ship after a collision In case of collision on i2c bus the controller which lost bus mastership stays as a slave for all subsequent transfers. This results in the i2c controller never writing to the bus for future transactions, resulting in i2c transfer timeouts. This fix checks for a collision on last I2C transaction and sets the I2COM_MASTER bit for the new transaction. Signed-off-by: Sachin Surendran Signed-off-by: Scott Wood --- drivers/i2c/busses/i2c-cpm.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/i2c/busses/i2c-cpm.c b/drivers/i2c/busses/i2c-cpm.c index 3823623baa48..9e6002108720 100644 --- a/drivers/i2c/busses/i2c-cpm.c +++ b/drivers/i2c/busses/i2c-cpm.c @@ -338,6 +338,14 @@ static int cpm_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num) tptr = 0; rptr = 0; + /* + * If there was a collision in the last i2c transaction, + * Set I2COM_MASTER as it was cleared during collision. + */ + if (in_be16(&tbdf->cbd_sc) & BD_SC_CL) { + out_8(&cpm->i2c_reg->i2com, I2COM_MASTER); + } + while (tptr < num) { pmsg = &msgs[tptr]; dev_dbg(&adap->dev, "R: %d T: %d\n", rptr, tptr); -- 2.20.1