Subject: Re: [i2c] [PATCH6/7] i2c: adds support for i2c bus on Freescale CPM1/CPM2 controllers

From: Jochen Friedrich <[email-masked]>
Date: Tue, 06 May 2008 17:19:39 +0200

Hi Wolfram,

>> +	/* Begin transmission */
>> +	setbits8(&i2c_reg->i2com, 0x80);
> Hardcoded value. (I also wonder if 0x81 might be more suitable, as it
> keeps the "be-a-master"-bit set. Still, both values work with my setup.)

>> +#ifdef I2C_CHIP_ERRATA
>> +	/*
>> +	 * Chip errata, clear enable. This is not needed on rev D4 CPUs.
>> +	 * Disabling I2C too early may cause too short stop condition
>> +	 */
>> +	udelay(4);
>> +	clrbits8(&i2c_reg->i2mod, 1);
> I was unable to find the corresponding errata document, still I wonder
> if it is a 0 which should have been written? The text says "clear" and
> according to the reference manual, this means the bit should be 0.

setbits8() and clrbits8() use a bitmask as second argument.

setbits8(&i2c_reg->i2com, 0x80) will set bit 7 on the i2com register but 
leave bit 0 untouched. Likewise, clrbits8(&i2c_reg->i2mod, 1) will clear bit 0.

Thanks,
Jochen