Re: [PATCH V7 1/2] i2c/adapter: Add bus recovery infrastructure

[Paul Carpenter <paul-YHLC2tV1sDlxR4N9A70vTlRxknfHcPLb9dF7HbQ/qKg@public.gmane.org>]

Viresh Kumar wrote:
> On 26 November 2012 17:15, Paul Carpenter
> <paul-YHLC2tV1sDlxR4N9A70vTlRxknfHcPLb9dF7HbQ/qKg@public.gmane.org> wrote:
>> Unless you know why the bus is stuck, how can you reset reminder this
>> method ONLY works if SCL is high and SDA probably was low and the slave
....

> Hi Paul,
> 
> I completely agree with what you said, and i also feel the need of it now.
> We don't have a solution for SCL stuck low, just by playing with pad values.
> And need some sort of reset of device, etc as mentioned by you earlier.
> 
> What we can do here, is check SCL's value and give an error message for
> SCL stuck low + return error.

Yes best method error to mean  "SCL stuck low or long clock stretch"

> The short circuit mentioned earlier will not happen in our case as we
> are setting gpio flags as OPEN_DRAIN and so we would never be writing
> 1 on SCL pad.

 From an earlier thread comment

 >> +    ret = gpio_request_one(bri->scl_gpio, GPIOF_OPEN_DRAIN |
 >> +            GPIOF_OUT_INIT_HIGH, "i2c-scl");
 >
 >I always get wary of people driving I2C with non-open-drain, especially
 >with stuck busses

I would want to know what "GPIOF_OUT_INIT_HIGH" did as that is
suspiciously driving output high at startup.


-- 
Paul Carpenter          | paul-YHLC2tV1sDlxR4N9A70vTlRxknfHcPLb9dF7HbQ/qKg@public.gmane.org
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