rtwn: add tx power training for RTL8812/RTL8821

[adrian]

Summary

This apparently kicks off TX power level self-calibration, which
can't hurt.

Locally tested:

• RTL8812AU, STA
• RTL8821AU, STA

Obtained from: Linux rtw88

[imp]

sys/dev/rtwn/rtl8812a/r12a_chan.c

194

So there are 3 writes? Why the loop?

[adrian]

sys/dev/rtwn/rtl8812a/r12a_chan.c

194

For now i'm just trying to mirror what the BSD licenced rtw88 code is doing - save the underflow, which I addressed but their driver doesn't.

Once I know it's all working OK, we should absolutely clean it up before landing. It could be done with three lines and some ternary operators.

[imp]

sys/dev/rtwn/rtl8812a/r12a_chan.c

194

ok, the write_data |= each loop w/o resetting between loops. Is that cool?

[bz]

sys/dev/rtwn/rtl8812a/r12a_chan.c

194

I think I'd love to know where the Linux rtw88 code is doing this? Do you have file:function -- at least we could then locally fix the underflow problem in rtw88 as well.

[adrian]

I'm talking with the rtw88 upstream maintainers on getting it fixed upstream too!

[bz]

In D47978#1097594, @adrian wrote:

I'm talking with the rtw88 upstream maintainers on getting it fixed upstream too!

You did NOT answer my question. You do understand that we are shipping this driver and try to maintain it. file:function please.

[adrian]

It's in rtw88xx.c:rtw88xxa_tx_power_training(), line 1609 in my checkout.

[bz]

In D47978#1097847, @adrian wrote:

It's in rtw88xx.c:rtw88xxa_tx_power_training(), line 1609 in my checkout.

Thanks. That 6.13-RCx code. If 8812 and 8821 are going to be integrated there this is going to be fun as I'll import that code along with rtw88.