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authorDirk Eibach <dirk.eibach@gdsys.cc>2014-10-29 15:56:43 +0100
committerHeiko Schocher <hs@denx.de>2014-11-10 06:44:15 +0100
commit7e78f7ad7f7f666598bc2ff115ea7a35f8e059f1 (patch)
tree32f580faeeed7ad52997208493dd936b54c80313 /drivers
parent11ada9225a16ed2d8ddbf0715a2416245a777cbc (diff)
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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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/i2c/ppc4xx_i2c.c9
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/i2c/ppc4xx_i2c.c b/drivers/i2c/ppc4xx_i2c.c
index e7a15ba..d2ff86c 100644
--- 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;