Prev: [hg:v4l-dvb] Fix FW_LOADER depencency at v4l/dvb
Next: [PATCH] hostap: procfs fix for hostap_fw.c
From: Jochen Friedrich on 6 May 2008 11:30
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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo(a)vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
 | 
Pages: 1
Prev: [hg:v4l-dvb] Fix FW_LOADER depencency at v4l/dvb
Next: [PATCH] hostap: procfs fix for hostap_fw.c