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

[Haojian Zhuang]

On Thu, Nov 25, 2010 at 10:30 AM, Haojian Zhuang
<haojian.zhuang at gmail.com> wrote:
> On Thu, Nov 25, 2010 at 5:20 AM, Sebastian Andrzej Siewior
> <bigeasy at linutronix.de> 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 at linutronix.de>
>> Signed-off-by: Dirk Brandewie <dirk.brandewie at gmail.com>
>> ---
>>  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.
>
Excuse me that my previous comments are for PXA master mode.

I think that you're focused on pxa working on slave mode. But if pxa
is working in master mode, it seems that we needn't reset I2C
controller since it doesn't help.

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