Re: [RFC/RFT 1/4] mt76x02: configure basic rates and fallback on STA mode

[Stanislaw Gruszka <sgruszka@redhat.com>]

On Thu, Nov 08, 2018 at 05:02:14PM +0100, Felix Fietkau wrote:
> >> > +       if (changed & BSS_CHANGED_BASIC_RATES &&
> >> > +           vif->type == NL80211_IFTYPE_STATION) {
> >> > +               mt76_wr(dev, MT_LEGACY_BASIC_RATE, info->basic_rates);

It's a bit hard to interpret how vendor driver set LEGACY_BIT_RATE
in MlmeUpdateTxRates(). It seems to always enable bits for
OFDM6/OFDM12/OFDM24 (bitmask 0x150) or maybe just do this for 5GHz,
I'm not sure. Need more investigation on this.
 
> >> > +               mt76_wr(dev, MT_VHT_HT_FBK_CFG0, 0x65432100);
> >> > +               mt76_wr(dev, MT_VHT_HT_FBK_CFG1, 0xedcba980);
> >> > +               mt76_wr(dev, MT_LG_FBK_CFG0, 0xedcba988);
> >> > +               if (is_mt76x2(dev))
> >> > +                       mt76_wr(dev, MT_LG_FBK_CFG1, 0x87872100);
> >> > +               else
> >> > +                       mt76_wr(dev, MT_LG_FBK_CFG1, 0x00872100);
> >> > +       }
> >> > +
> >> 
> >> since these values are constant, why not put them init_vals?
> > 
> > I wanted them to be used only in STA mode like vendor driver does.
> > However if we will have AP+STA , we still will configure them,
> > so better to configure them anyway and put in init_vals .
> Yes, I think we should put them in initvals. Also, I think we should
> keep the values the shared between mt76x0 and mt76x2.
> 
> For MT_LG_FBK_CFG1 there is no need to make a distinction between 76x2
> and 76x0, because 76x0 will simply ignore the upper values (they apply
> to 2SS transmission only).
> Also, I don't think MT_VHT_HT_FBK_CFG1 even gets used on mt76x0, because
> it is for 2SS rates only. However, the value in there seems more useful
> than the one we currently use on mt76x2, because it allows fallback from
> 2SS MCS0 to 1SS MCS0.
> The contents of MT_LG_FBK_CFG0 also match the default initialization
> values documented in the 7612E datasheet.
> 
> I don't think there is any meaningful difference between the 76x2 and
> the 76x0 MAC except for the missing 2SS support.

Since there are different initvals tables for mt76x2 and mt76x0, I use
different values of MT_LG_FBK_CFG1. Will post a patches soon, please
comment there, if something is not correct.

Thanks
Stanislaw