Re: Question about TX power

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

Am Fri, May 09, 2025 at 03:49:55PM +0200 schrieb Sebastian Gottschall:
> 
> Am 09.05.2025 um 13:59 schrieb Alexander Wilhelm:
> > 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.
> my answer might be not accurate here. which chipset we are talking about for
> ath11k?

I'm using QCN9074 chipset.

> > 
> > Best regards
> > Alexander Wilhelm
> >