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>
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 @@
/* 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;
}