[U-Boot] [PATCH 3/3] mxc_i2c: remove setting speed at each start

[Dirk Behme]

On 06.05.2012 17:27, Stefano Babic wrote:
> On 06/05/2012 01:06, Marek Vasut wrote:
>> Dear Troy Kisky,
>>
>>> On 5/5/2012 2:36 PM, Marek Vasut wrote:
>>>> Dear Troy Kisky,
>>>>
>>>>> On 5/5/2012 6:08 AM, Marek Vasut wrote:
>>>>>> Dear Troy Kisky,
>>>>>>
>>>>>>> On 4/24/2012 8:33 PM, Troy Kisky wrote:
>>>>>>>> Other then being very weird, this code was also wrong.
>>>>>>>> For example, say I set speed to 100K. I'll read back the speed
>>>>>>>> as 85937. But the speed is really 85937.5, so we I reset
>>>>>>>> the speed to 85937, I'll get 73660.7. After a couple of transactions
>>>>>>>> my speed is now exactly 68750 so it will remain there.
>>>>>>>>
>>>>>>>> Signed-off-by: Troy Kisky<troy.kisky at boundarydevices.com>
>>>>>>>> ---
>>>>>>>>
>>>>>>>>     drivers/i2c/mxc_i2c.c |    6 ------
>>>>>>>>     1 files changed, 0 insertions(+), 6 deletions(-)
>>>>>>>>
>>>>>>>> diff --git a/drivers/i2c/mxc_i2c.c b/drivers/i2c/mxc_i2c.c
>>>>>>>> index 416ffee..fc68062 100644
>>>>>>>> --- a/drivers/i2c/mxc_i2c.c
>>>>>>>> +++ b/drivers/i2c/mxc_i2c.c
>>>>>>>> @@ -231,12 +231,6 @@ int i2c_imx_start(void)
>>>>>>>>
>>>>>>>>     	struct mxc_i2c_regs *i2c_regs = (struct mxc_i2c_regs *)I2C_BASE;
>>>>>>>>     	unsigned int temp = 0;
>>>>>>>>     	int result;
>>>>>>>>
>>>>>>>> -	int speed = i2c_get_bus_speed();
>>>>>>>> -	u8 clk_idx = i2c_imx_get_clk(speed);
>>>>>>>> -	u8 idx = i2c_clk_div[clk_idx][1];
>>>>>>>> -
>>>>>>>> -	/* Store divider value */
>>>>>>>> -	writeb(idx,&i2c_regs->ifdr);
>>>>>>>>
>>>>>>>>     	/* Enable I2C controller */
>>>>>>>>     	writeb(0,&i2c_regs->i2sr);
>>>>>>> Marek would you care to ack/nak this? It is deleting code that you
>>>>>>> added.
>>>>>> Ok, who will set the controller speed if you remove this?
>>>>> i2c_init is the only function that writes the ifdr register after this
>>>>> patch.
>>>> And i2c_init() is called on every boot. Correct?
>>>>
>>>>> This is fine because this register is not affected by a software reset.
>>>> I take it you verified this or that you're sure here :)
>>> I haven't looked at every reference manual, but if some oddball chip
>>> needs it reinitialized after
>>> a software reset, then the fix should go into the i2c_reset function,
>>> not i2c_imx_start.
>>> And this patch would not be introducing a regression for the oddball
>>> chip anyway.
> 
> Ok, everything was already clear, and I can also add my:
> 
> Acked-by: Stefano Babic <sbabic at denx.de>

Same for this one: Is this applied anywhere? It doesn't seem to be part 
of v2012.07-rc1?

Best regards

Dirk