Re: [PATCH 6/7] i2c/pxa2xx: reset the chip if the bus is not free

[Haojian Zhuang <haojian.zhuang-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Thu, Nov 25, 2010 at 5:20 AM, Sebastian Andrzej Siewior
<bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org> wrote:
> I haven't seen this (yet) during a normal transfer but starting
> i2cdetect seems to hang the bus. On my Sodaville board, i2cdetect runs
> fine on bus zero and runs into timeouts on bus one and two. The chip
> never recovers from this condition. The following transfers hang as
> well. The ISR_UB never disappears.
> Issuing a chip reset fixes the timeout and following transfer succeed.
>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>
> Signed-off-by: Dirk Brandewie <dirk.brandewie-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/i2c/busses/i2c-pxa.c |   35 +++++++++++++++++++----------------
>  1 files changed, 19 insertions(+), 16 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
> index bd4b885..1a48470 100644
> --- a/drivers/i2c/busses/i2c-pxa.c
> +++ b/drivers/i2c/busses/i2c-pxa.c
> @@ -257,23 +257,7 @@ static void i2c_pxa_abort(struct pxa_i2c *i2c)
>               _ICR(i2c));
>  }
>
> -static int i2c_pxa_wait_bus_not_busy(struct pxa_i2c *i2c)
> -{
> -       int timeout = DEF_TIMEOUT;
>
> -       while (timeout-- && readl(_ISR(i2c)) & (ISR_IBB | ISR_UB)) {
> -               if ((readl(_ISR(i2c)) & ISR_SAD) != 0)
> -                       timeout += 4;
> -
> -               msleep(2);
> -               show_state(i2c);
> -       }
> -
> -       if (timeout < 0)
> -               show_state(i2c);
> -
> -       return timeout < 0 ? I2C_RETRY : 0;
> -}
>
>  static int i2c_pxa_wait_master(struct pxa_i2c *i2c)
>  {
> @@ -425,6 +409,25 @@ static void i2c_pxa_reset(struct pxa_i2c *i2c)
>        udelay(100);
>  }
>
> +static int i2c_pxa_wait_bus_not_busy(struct pxa_i2c *i2c)
> +{
> +       int timeout = DEF_TIMEOUT;
> +
> +       while (timeout-- && readl(_ISR(i2c)) & (ISR_IBB | ISR_UB)) {
> +               if ((readl(_ISR(i2c)) & ISR_SAD) != 0)
> +                       timeout += 4;
> +
> +               msleep(2);
> +               show_state(i2c);
> +       }
> +
> +       if (timeout < 0) {
> +               show_state(i2c);
> +               i2c_pxa_reset(i2c);
> +       }

Even you reset I2C controller, it shouldn't help you since bus isn't
free. I thinkt that you should reset I2C bus before you reseting I2C
controller.

> +
> +       return timeout < 0 ? I2C_RETRY : 0;
> +}
>
>  #ifdef CONFIG_I2C_PXA_SLAVE
>  /*
> --
> 1.7.3.2
>
>
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