ppc4xx: Fix i2c repeated start

Debugging some i2c trouble I saw on my scope that repeated
start is not working properply. The 4xx even held clock pulled down
after transfers. Having a look in the driver I realized
that IIC_CNTL_RPST is set on that part of the transfer that should
begin with a repeated start. But repeated start is about not sending a
stop condition, so IIC_CNTL_RPST has to be set on the last transfer
before the repeated start happens.

Signed-off-by: Dirk Eibach <dirk.eibach@gdsys.cc>
Reviewed-by: Stefan Roese <sr@denx.de>

diff --git a/drivers/i2c/ppc4xx_i2c.c b/drivers/i2c/ppc4xx_i2c.c
index e7a15ba6448a7600ac5f8a077840e2e98533d2e3..d2ff86c99abac6a5ca14c5386bf1ad446c5e100e 100644 (file)
--- a/drivers/i2c/ppc4xx_i2c.c
+++ b/drivers/i2c/ppc4xx_i2c.c
@@ -158,8 +158,7 @@ static void ppc4xx_i2c_init(struct i2c_adapter *adap, int speed, int slaveaddr)
  *
  * Typical case is a Write of an addr followd by a Read. The
  * IBM FAQ does not cover this. On the last byte of the write
- * we don't set the creg CHT bit, and on the first bytes of the
- * read we set the RPST bit.
+ * we don't set the creg CHT bit but the RPST bit.
  *
  * It does not support address only transfers, there must be
  * a data part. If you want to write the address yourself, put
@@ -247,6 +246,10 @@ static int _i2c_transfer(struct i2c_adapter *adap,
                if ((!cmd_type && (ptr == addr)) || ((tran + bc) != cnt))
                        creg |= IIC_CNTL_CHT;
 
+               /* last part of address, prepare for repeated start on read */
+               if (cmd_type && (ptr == addr) && ((tran + bc) == cnt))
+                       creg |= IIC_CNTL_RPST;
+
                if (reading) {
                        creg |= IIC_CNTL_READ;
                } else {
@@ -314,8 +317,6 @@ static int _i2c_transfer(struct i2c_adapter *adap,
                        cnt = data_len;
                        tran = 0;
                        reading = cmd_type;
-                       if (reading)
-                               creg = IIC_CNTL_RPST;
                }
        }
        return result;