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

[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.
This is fine because this register is not affected by a software reset.
If this register were affected by a software reset, then the current code
would not work either, as i2c_imx_start is reading from this register before
trying(and often failing) to set it to the same value.


>
>> Thanks
>> Troy
> Best regards,
> Marek Vasut
>