Question about TX power
Sebastian Gottschall
s.gottschall at dd-wrt.com
Fri May 9 03:54:47 PDT 2025
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
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