Re: Question about TX power

[Sebastian Gottschall <s.gottschall@dd-wrt.com>]

Am 09.05.2025 um 10:43 schrieb Alexander Wilhelm:
> Hello devs,
>
> I'd like to understand how TX power setting works on ath11k devices. For example
> when I'm using channel 36 for ETSI based regulatory domain, I can set up to 23
> dBm. But then I get only 20 dBm as a result. On different channels and/or
> regulatory domains I get different reductions. I tried to follow the source
> code. As far as I understood is that 'ath11k_mac_txpower_recalc' sets the
> correct values and 'ath11k_mac_op_get_txpower' return the different one.
>
> My question is where this reduction offset is encoded. Is it in the module's
> firmware or is it part of the boardfile? Thank you in advance.
>
>
> Best regards
> Alexander Wilhelm

the boardfile contains chipset specific calibration data which also 
defines the hardware power limits (more specific data also included in 
the on board calibration flash of the device or if its a router, in 
flash memory of the router itself. in addition it includes a regulatory 
database which is used by the firmware for managing the total power. you 
have also to consider that the 23dbm are specified without antenna gain.
so if the antenna gain is 3 dbm, you get 20 dbm in total. this antenna 
gain may again be specified in the boardfile.
so you will not find your answers in any sourcecode. its all encoded in 
binary data.

Sebastian