Re: [PATCH 2/4] i2c: imx: only imx1 needs disable delay

Richard Zhao
2009-10-01T07:52:15Z

On Thu, Oct 1, 2009 at 3:26 PM, Sascha Hauer <s.hauer@pengutronix.de> wrote:
> On Thu, Oct 01, 2009 at 09:13:31AM +0800, Richard Zhao wrote:
>> check cpu_is_mx1() when set disable_delay.
>>
>> Signed-off-by: Richard Zhao <linuxzsc@gmail.com>
>>
>> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
>> index 156cc95..c1e541c 100644
>> --- a/drivers/i2c/busses/i2c-imx.c
>> +++ b/drivers/i2c/busses/i2c-imx.c
>> @@ -254,14 +254,16 @@ static void __init i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
>>       /* Write divider value to register */
>>       writeb(i2c_clk_div[i][1], i2c_imx->base + IMX_I2C_IFDR);
>>
>> -     /*
>> -      * There dummy delay is calculated.
>> -      * It should be about one I2C clock period long.
>> -      * This delay is used in I2C bus disable function
>> -      * to fix chip hardware bug.
>> -      */
>> -     i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
>> -             + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
>> +     if (cpu_is_mx1()) {
>> +             /*
>> +              * There dummy delay is calculated.
>> +              * It should be about one I2C clock period long.
>> +              * This delay is used in I2C bus disable function
>> +              * to fix chip hardware bug.
>> +              */
>> +             i2c_imx->disable_delay = (500000U * i2c_clk_div[i][0]
>> +                     + (i2c_clk_rate / 2) - 1) / (i2c_clk_rate / 2);
>> +     }
>
> I think you should put the udelay(i2c_imx->disable_delay) in
> cpu_is_mx1() rather than the calculation.
>
> Sascha
>
>
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>
Do you think udelay(0) wast any more time than if()?
And Could I get all you comments in a single patch loop?

Thanks
Richard