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authorDirk Eibach <dirk.eibach@gdsys.cc>2014-10-29 15:56:44 +0100
committerHeiko Schocher <hs@denx.de>2014-11-10 06:44:30 +0100
commitb97cd6814ec08be56225975a050ee486bfa7c13a (patch)
treed62bf2d70db726db65020427cbcb793c5bd2f5aa /drivers/i2c/ppc4xx_i2c.c
parent7e78f7ad7f7f666598bc2ff115ea7a35f8e059f1 (diff)
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ppc4xx: Handle i2c stuck on combined xfer
ppc4xx i2c master gets stuck on errors while repeated start is active. Can be easily reproduced by "i2c md" on an unpopulated i2c address. There is not stop condition given, scl remains pulled low. The only way out seems to be doing a stop manually and then a soft reset. Signed-off-by: Dirk Eibach <dirk.eibach@gdsys.cc> Reviewed-by: Stefan Roese <sr@denx.de>
Diffstat (limited to 'drivers/i2c/ppc4xx_i2c.c')
-rw-r--r--drivers/i2c/ppc4xx_i2c.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/drivers/i2c/ppc4xx_i2c.c b/drivers/i2c/ppc4xx_i2c.c
index d2ff86c..df88885 100644
--- a/drivers/i2c/ppc4xx_i2c.c
+++ b/drivers/i2c/ppc4xx_i2c.c
@@ -289,6 +289,27 @@ static int _i2c_transfer(struct i2c_adapter *adap,
/* Transfer aborted? */
if (status & IIC_EXTSTS_XFRA)
result = IIC_NOK_XFRA;
+ /* Is bus free?
+ * If error happened during combined xfer
+ * IIC interface is usually stuck in some strange
+ * state without a valid stop condition.
+ * Brute, but working: generate stop, then soft reset.
+ */
+ if ((status & IIC_EXTSTS_BCS_MASK)
+ != IIC_EXTSTS_BCS_FREE){
+ u8 mdcntl = in_8(&i2c->mdcntl);
+
+ /* Generate valid stop condition */
+ out_8(&i2c->xtcntlss, IIC_XTCNTLSS_SRST);
+ out_8(&i2c->directcntl, IIC_DIRCNTL_SCC);
+ udelay(10);
+ out_8(&i2c->directcntl,
+ IIC_DIRCNTL_SCC | IIC_DIRCNTL_SDAC);
+ out_8(&i2c->xtcntlss, 0);
+
+ ppc4xx_i2c_init(adap, (mdcntl & IIC_MDCNTL_FSM)
+ ? 400000 : 100000, 0);
+ }
} else if ( status & IIC_STS_PT) {
result = IIC_NOK_TOUT;
}