Re: [PATCH 1/3] ath9k: use consistent value for REDUCE_SCALED_POWER_BY_THREE_CHAIN

[Felix Fietkau <nbd@openwrt.org>]

On 2012-04-14 10:01 PM, Gabor Juhos wrote:
> The REDUCE_SCALED_POWER_BY_THREE_CHAIN symbol is
> defined in different eeprom files, and the value
> varies between the different files.
> 
> In eeprom_def.c and in ar9003_eeprom.c the value
> of the symbol is 9, however the comments in these
> files indicates the value should be 10*log10(3)*2
> which is 9.54242509439325. Replace the the value
> to 10 in these files.
> 
> Also add comments to eeprom_9287.c.
> 
> Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
I think we should keep the value 9.
If I understand the logic behind the power increase through chain
combining properly, this value only describes the worst-case (wrt.
regulatory compliance) upper limit of tx power, whereas in practice the
measured combined power output will be much lower than that due to
signal/phase differences.
Regulatory compliance is already properly tested on all devices with the
truncated value 9, so I don't think that we need to be even more
conservative and round up here.

- Felix