[U-Boot] [PATCH] 85xx: Using proper I2C source clock divider for MPC8544

Wolfgang Grandegger wg at grandegger.com
Tue Oct 14 23:38:34 CEST 2008


Kumar Gala wrote:
>>>>> thanks.  How did you do the measurements that got you this 1.5x  
>>>>> factor?
>>>> This afternoon I re-measured the I2C bus clock frequency with the
>>>> oscilloscope at the I2C clock line on our Socrates MPC8544 board.  
>>>> With
>>>> the patch applied, I measured the correct frequency of 100 kHz.  
>>>> Without,
>>>> it was a factor of 1.5 too high.
>>> are you able to change cfg_seq_freq on the board?
>> At least I don't know how. It's defined via hardware strap, I imagine.
> 
> Its is.. not sure if you have schematics for the board.  If you do  
> look to see if LWE_B is wired to anything.

I'm going to ask the customer. But even if it's wired, the bit in the
cfg_sec_freq register should reflect properly that case.

Wolfgang.


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