[Patch v2 1/2] 5200/mpc: improve i2c bus error recovery

[Joakim Tjernlund]

> @@ -93,20 +94,23 @@ static irqreturn_t mpc_i2c_isr(int irq,
>   /* Sometimes 9th clock pulse isn't generated, and slave doesn't release
>    * the bus, because it wants to send ACK.
>    * Following sequence of enabling/disabling and sending start/stop generates
> - * the pulse, so it's all OK.
> + * the 9 pulses, so it's all OK.
>    */
>   static void mpc_i2c_fixup(struct mpc_i2c *i2c)
>   {
> -   writeccr(i2c, 0);
> -   udelay(30);
> -   writeccr(i2c, CCR_MEN);
> -   udelay(30);
> -   writeccr(i2c, CCR_MSTA | CCR_MTX);
> -   udelay(30);
> -   writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN);
> -   udelay(30);
> -   writeccr(i2c, CCR_MEN);
> -   udelay(30);
> +   int k;
> +   u32 delay_val = 1000000 / i2c->real_clk + 1;
> +
> +   if (delay_val < 2)
> +      delay_val = 2;
> +
> +   for (k = 9; k; k--) {
> +      writeccr(i2c, 0);
> +      writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN);
> +      udelay(delay_val);
> +      writeccr(i2c, CCR_MEN);
> +      udelay(delay_val << 1);
> +   }
>   }

I am curious, didn't old method work with by just wrapping
a for(k=9; k; k--) around it? How did the wave form look?

   Jocke