rtwn: announce VHT support for RTL8812AU/RTL8821AU.

[adrian]

Summary

Although the transmit path doesn't yet support VHT rates (because
the rate control and rate representation in net80211 doesn't yet
know about VHT rates) the NIC will receive VHT frames but only
transmit HT frames.

Locally tested:

• RTL8812AU, STA mode

[bz]

sys/dev/rtwn/rtl8812a/usb/r12au_attach.c

186

While here; the | goes at the end of the line; also other file

[fuz]

Can this code be deduplicated and shared between the two driver instances?
The loop feels like it could be eliminated, e.g. with code like

uint32_t supported;

supported = 0xaaaa & ((1 << sc->ntxchains) - 1);
tx_mcs |= IEEE80211_VHT_MCS_SUPPORT_0_9 * supported;
tx_mcs |= IEEE80211_VHT_MCS_NOT_SUPPORTED * (0xaaaa - supported);

supported = 0xaaaa & ((1 << sc->nrxchains) - 1);
rx_mcs |= IEEE80211_VHT_MCS_SUPPORT_0_9 * supported;
rx_mcs |= IEEE80211_VHT_MCS_NOT_SUPPORTED * (0xaaaa - supported);

Though it seems that would be a lot less clean than what you currently have.

[bz]

bz and fuz

[adrian]

In D48103#1099187, @fuz wrote:

Can this code be deduplicated and shared between the two driver instances?
The loop feels like it could be eliminated, e.g. with code like

uint32_t supported;

supported = 0xaaaa & ((1 << sc->ntxchains) - 1);
tx_mcs |= IEEE80211_VHT_MCS_SUPPORT_0_9 * supported;
tx_mcs |= IEEE80211_VHT_MCS_NOT_SUPPORTED * (0xaaaa - supported);

supported = 0xaaaa & ((1 << sc->nrxchains) - 1);
rx_mcs |= IEEE80211_VHT_MCS_SUPPORT_0_9 * supported;
rx_mcs |= IEEE80211_VHT_MCS_NOT_SUPPORTED * (0xaaaa - supported);

Though it seems that would be a lot less clean than what you currently have.

oh god binary arithmetic funsies. ;-)

Honestly this is something that's going to show up in all of the 11ac drivers in some way, so I should probably write a net80211 vht function to populate it in this common case.

For now I think I'll refactor it out and put it in if_rtwn.c to be called by both paths, and any other 11ac chipset support that gets added here.

[adrian]

updates from fuz / bz review

[fuz]

Ok except for this one nit pick.

sys/dev/rtwn/if_rtwnvar.h

449

For consistency.