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ppc4xx: Handle i2c stuck on combined xfer

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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>
This commit is contained in:
Dirk Eibach 2014-10-29 15:56:44 +01:00 committed by Heiko Schocher
parent 7e78f7ad7f
commit b97cd6814e
2 changed files with 23 additions and 0 deletions
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2
arch/powerpc/include/asm/ppc4xx-i2c.h
View File

@ -72,6 +72,8 @@ struct ppc4xx_i2c {
#define IIC_EXTSTS_XFRA 0x01
#define IIC_EXTSTS_ICT 0x02
#define IIC_EXTSTS_LA 0x04
#define IIC_EXTSTS_BCS_MASK 0x70
#define IIC_EXTSTS_BCS_FREE 0x40
/* XTCNTLSS Register Bit definition */
#define IIC_XTCNTLSS_SRST 0x01

21
drivers/i2c/ppc4xx_i2c.c
View File

@ -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;
}