From a16d8aa4726a944ffc1616689ae34ff6a902faba Mon Sep 17 00:00:00 2001
From: Sachin Surendran <sachin.surendran@alliedtelesis.co.nz>
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 <sachin.surendran@alliedtelesis.co.nz>
Signed-off-by: Scott Wood <scottwood@freescale.com>
---
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 3823623baa481b..9e6002108720e4 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);
--
GitLab