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ppc4xx: Fix i2c repeated start

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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>
This commit is contained in:
Dirk Eibach 2014-10-29 15:56:43 +01:00 committed by Heiko Schocher
parent 11ada9225a
commit 7e78f7ad7f
1 changed files with 5 additions and 4 deletions
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9
drivers/i2c/ppc4xx_i2c.c
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@ -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;