Re: Question about TX power

[Alexander Wilhelm <alexander.wilhelm@westermo.com>]

Am Fri, May 09, 2025 at 12:54:47PM +0200 schrieb Sebastian Gottschall:
> 
> 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
> 

Alright, thank you Sebastian. Since I'm not using any calibration data on my
router/AP device, all data come from the boardfile. I've also understood that
the power limit reduction is related to antenna gain. I'll ask the radio module
manufacturer to create another boardfile for me that matches the required
antenna gain for my router/AP device.

Best regards
Alexander Wilhelm