Re: [PATCH 1/2] mt76: mt7615: init per-channel target power

[Lorenzo Bianconi <lorenzo.bianconi@redhat.com>]

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> On Tuesday, 11 June 2019 08:38:52 CEST Lorenzo Bianconi wrote:
> > +               switch (n_chains) {
> > +               case 4:
> > +                       target_power += 6;
> > +                       break;
> > +               case 3:
> > +                       target_power += 4;
> > +                       break;
> > +               case 2:
> > +                       target_power += 3;
> > +                       break;
> > +               default:
> > +                       break;
> > +               }
> 
> Any reason why you use different value for 3 chains than ath9k? Following 
> values are used in ath9k:
> 
> * 1 chain: 0 dB
> * 2 chains: 3 dB (max combined gain ~3.010299956639812 dB)
> * 3 chains: 5 dB (max combined gain ~4.771212547196624 dB)

Hi Sven,

I just rounded down the values, but we can use 5db (in this case we need to fix
it even in mt76_get_power(), so I will do it in a different patch)

Regards,
Lorenzo

> * 4 chains: not supported (max combined gain 6.020599913279624 dB)
> 
> Here are the definitions from ath9k (values are saved in .5 dB steps)
> 
>     drivers/net/wireless/ath/ath9k/eeprom.h:#define POWER_CORRECTION_FOR_TWO_CHAIN          6  /* 10*log10(2)*2 */
>     drivers/net/wireless/ath/ath9k/eeprom.h:#define POWER_CORRECTION_FOR_THREE_CHAIN        10 /* 10*log10(3)*2 */
> 
> Kind regards,
> 	Sven



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