[U-Boot] [PATCH 17/24] mxc_i2c: add bus recovery support

[Troy Kisky]

On 6/24/2012 1:51 AM, Heiko Schocher wrote:
> Hello Troy,
>
> On 22.06.2012 06:12, Troy Kisky wrote:
>> Toggling the scl line 9 clocks is the standard
>> way of returning a locked up bus to idle condition.
>>
>> Signed-off-by: Troy Kisky<troy.kisky at boundarydevices.com>
>> ---
>>   drivers/i2c/mxc_i2c.c |   26 ++++++++++++++++++++++++++
>>   1 file changed, 26 insertions(+)
>>
>> diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
>> index ec05798..339bb6f 100644
>> --- a/drivers/i2c/mxc_i2c.c
>> +++ b/drivers/i2c/mxc_i2c.c
>> @@ -246,6 +246,8 @@ static int i2c_init_transfer_(struct mxc_i2c_regs 
>> *i2c_regs,
>>       return 0;
>>   }
>>
>> +static void toggle_i2c(void *i2c_regs);
>> +
>>   static int i2c_init_transfer(struct mxc_i2c_regs *i2c_regs,
>>           uchar chip, uint addr, int alen)
>>   {
>> @@ -264,6 +266,7 @@ static int i2c_init_transfer(struct mxc_i2c_regs 
>> *i2c_regs,
>>           if (ret != -ERESTART)
>>               writeb(0,&i2c_regs->i2cr);    /* Disable controller */
>>           udelay(100);
>> +        toggle_i2c(i2c_regs);
>>       }
>>       printf("%s: give up i2c_regs=%p\n", __func__, i2c_regs);
>>       return ret;
>> @@ -381,6 +384,29 @@ void *get_base(void)
>>   #endif
>>   }
>>
>> +static struct i2c_parms *i2c_get_parms(void *base)
>> +{
>> +    int i = 0;
>> +    struct i2c_parms *p = g_parms;
>> +    while (i<  ARRAY_SIZE(g_parms)) {
>> +        if (p->base == base)
>> +            return p;
>> +        p++;
>> +        i++;
>> +    }
>> +    printf("Invalid I2C base: %p\n", base);
>> +    return NULL;
>> +}
>> +
>> +static void toggle_i2c(void *base)
>> +{
>> +    struct i2c_parms *p = i2c_get_parms(base);
>> +    if (!p)
>> +        return;
>> +    if (p->toggle_fn)
>> +        p->toggle_fn(p->toggle_data);
>> +}
>> +
>>   int i2c_read(uchar chip, uint addr, int alen, uchar *buf, int len)
>>   {
>>       return bus_i2c_read(get_base(), chip, addr, alen, buf, len);
>
> Hmm.. why you cannot use the CONFIG_SYS_I2C_INIT_BOARD and 
> i2c_init_board()
The fsl_i2c.c file uses CONFIG_SYS_I2C_INIT_BOARD to call the function.

I could add similar code to mxc_i2c.c, (adding a bus number parameter),
but I do prefer the way I implemented it.
Why should the bus recovery be limited to i2c_init?

> for unblocking the i2c bus? And where is the function, which really
> toggles the SCL pin, as you described in the commit message?

Your right, my commit message is misleading, I'll update.
The actual toggling function is in a later patch.
Thanks for the review

Troy