[U-Boot] [PATCH v1 2/2] ppc4xx: Handle i2c stuck on combined xfer

[Heiko Schocher]

Hello Dirk,

Am 29.10.2014 15:56, schrieb dirk.eibach at gdsys.cc:
> From: Dirk Eibach<dirk.eibach at gdsys.cc>
>
> 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 at gdsys.cc>
> ---
>
>   arch/powerpc/include/asm/ppc4xx-i2c.h |  2 ++
>   drivers/i2c/ppc4xx_i2c.c              | 21 +++++++++++++++++++++
>   2 files changed, 23 insertions(+)
>
> diff --git a/arch/powerpc/include/asm/ppc4xx-i2c.h b/arch/powerpc/include/asm/ppc4xx-i2c.h
> index 09189cf..df97f17 100644
> --- a/arch/powerpc/include/asm/ppc4xx-i2c.h
> +++ b/arch/powerpc/include/asm/ppc4xx-i2c.h
> @@ -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
> 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?

Nitpick only: wrong comment style ... Is it OK for you, if I fix it,
when applying this patch?

Thanks!

bye,
Heiko
> +			 * 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;
>   		}

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