From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stefan Roese <sr@denx.de>
Date: Fri, 05 Apr 2013 08:04:54 +0200
Subject: [U-Boot] PPC4XX Custom Board - Failing to read I2C
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	<1365120299377-151609.post@n7.nabble.com>
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On 05.04.2013 02:04, txcotrader wrote:
> After looking deeper I've found a difference in register values when
> performing drivers/i2c/ppc4xx_i2c.c->i2c_transfer function.
> 
> v1.7.02 code yields:
> 
> /* Transfer is in progress
>          * we have to wait for upto 5 bytes of data
>          * 1 byte chip address+r/w bit then bc bytes
>          * of data.
>          * udelay(10) is 1 bit time at 100khz
>          * Doubled for slop. 20 is too small.
>          */
>         i = 2*5*8;
>         do {
>             /* Get status */
>             status = in_8((u8 *)IIC_STS);
>             printf("gd_ do status->i = %d, status = %d\n", i, status);
>             udelay(20);
>             i--;
>         } while ((status & IIC_STS_PT) && !(status & IIC_STS_ERR) && (i >
> 0));
> 
> gd_ do status->i = 80, status = 40
> 
> 
> v2013.01.01 Yields:
>         i = 2 * 5 * 8;
>         do {
>             /* Get status */
>             status = in_8(&i2c->sts);
>             printf("gd_ do status->i = %d, status = %d\n", i, status);
>             udelay(10);
>             i--;
>         } while ((status & IIC_STS_PT) && !(status & IIC_STS_ERR) &&
>              (i > 0));
> 
> gd_ do status->i = 80, status = 40
> 
> v1.7.02 - include/4xx_i2c.h:#define IIC_STS	
> (I2C_REGISTERS_BASE_ADDRESS+IICSTS)
> v2013.01.01 - struct ppc4xx_i2c *i2c = (struct ppc4xx_i2c *)I2C_BASE_ADDR;
> 
> Newb question, but I should be able to add an offset to correct this issue
> right?

The resulting addresses should be the same. The old version uses the
offset via a define and the new one the (recommended) struct access to
the register. I suggest you print the resulting address to verify that
it really is the same.

Thanks,
Stefan