[PATCH 0/4] wifi: rtw89: advertise WFA-certified EHT capabilities for 8922a

[Louis Kotze <loukot@gmail.com>]

This series advances rtw89 EHT capability advertisement to match what
Realtek's own RTL8922AE silicon is certified for by the Wi-Fi Alliance
in WFA Cert WFA129313 (RTL8922AE 802.11be and Bluetooth combo module,
2024-05-23, FW 6102.24.109.0,
https://api.cert.wi-fi.org/api/certificate/download/public?variantId=129706).

The cert lists EMLSR, STR, Multi-RU, MCS 8-13, DL/UL MU-MIMO, UL OFDMA,
SU-MIMO, beamforming sounding, multi-link reconfiguration, advertised
TID-to-link mapping, BSS critical update, A-MPDU with A-MSDU, LDPC,
operating mode indication, EPCS priority access, and several other
features as certified for this chip. The driver currently advertises
some of these and hard-zeroes others. This series fills the gap for
four cap surfaces:

  Patch 1/4: EML Capabilities (EMLSR_SUPP + padding/transition delays)
             plus Restricted TWT (EHT MAC Cap0). EMLSR is explicitly
             listed in the WFA cert. R-TWT is silicon-supported per the
             chip's documented EHT MAC capabilities.
  Patch 2/4: Multi-RU OFDMA receive cap (CAP5_RX_LESS_242_TONE_RU_SUPP).
             Multi-RU is verbatim in the WFA cert.
  Patch 3/4: MLD operation caps — TID-to-link mapping (SAME) +
             Link Reconfiguration support. Both verbatim in the WFA
             cert. Uses FIELD_PREP_CONST() (already used in this driver
             at usb.c:784-787) and matches the bit pattern Intel uses
             for its Wi-Fi 7 STAs (IWL_MVM_MLD_CAPA_OPS in
             iwlwifi/mvm/mac80211.c). MAX_SIMUL_LINKS is left at 0
             (= 1 max simul link) consistent with the EMLSR-only
             operating mode the driver implements.
  Patch 4/4: EHT OM Control (MAC Cap0). "Operating mode indication" is
             verbatim in the WFA cert; mt7925 + iwlwifi mvm + hwsim
             precedent.

Industry context: this series advances rtw89 along the same axis every
in-tree Linux WiFi 7 driver currently occupies — MLSR/EMLSR fast-switch
on a single physical radio. True STR multi-radio aggregation is not
implemented by any in-tree driver as of v6.15+ (iwlwifi, mt7925, ath12k,
rtw89). The only known shipping consumer STR adapter on any OS is the
Ubiquiti UniFi AirWire (closed firmware, UniFi-AP-only). This series
does not attempt STR; it brings rtw89 EMLSR negotiation in line with
the other three drivers.

Testing: applied as a stack to the morrownr/rtw89 OOT clone on Linux
6.19.11 (Bazzite F44) running RTL8922AU USB; tested against TP-Link
Deco BE63 mesh (5-node) for 48h+ continuous association. Verified caps
appear in `iw phy` output (Restricted TWT, OM Control, "Rx 1024-QAM
And 4096-QAM < 242-tone RU"). active_links = 0x4 confirms expected
EMLSR mode. wifi-health-check sweep (11 checks: wpa override, rpm-ostree
state, rtw89 build, SELinux, NM dispatchers, regdomain, link state,
SELinux AVC rate, MLO link count) passes 11/11 throughout the soak.

A/B comparison patched vs unpatched, 3-NIC concurrent reverse-mode
iperf3, 5 reps patched + 3 reps unpatched per SSID, signal -10 to
-25 dBm: no measurable throughput delta (MLO patched mean 1128 Mbps
vs unpatched mean 1174 Mbps; 6 GHz patched mean 1099 Mbps vs unpatched
mean 1169 Mbps; deltas well within ±5% noise floor and dominated by
per-test MCS variation, not patch state). The patches enable correct
cap advertisement matching what RTL8922A silicon supports per the
WFA cert; they do not aim to deliver throughput improvement in
steady-state operation against this AP. Patches are about correctness
and standards-compliance, not throughput.

Tested only on RTL8922AU (USB variant); rtw89_init_eht_cap() and the
iftype-ext-cap struct are shared across the rtw89 chip family. Non-AU
variant testing from anyone with rtw89-supported hardware is welcome.

Note on EMLMR (EML Cap bit 7): the WFA cert does NOT list EMLMR for
this chip. RTL8922A has rf_path_num=2 (single 2T2R RF block shared
across bands), and the driver has no EMLMR enum, firmware H2C path,
or PHY register block. EMLSR is the architectural ceiling for this
silicon; this series does not advertise EMLMR.

Note on follow-up: a separate audit identified five further capability
fields hard-zeroed in rtw89_init_eht_cap() (EHT A-MPDU exponent,
partial-BW DL/UL MU-MIMO, MCS 14-15, sounding dimensions, 1024/4096-QAM
wider-BW DL-OFDMA). Some of these are likely silicon ceilings (MCS 14-15
is consistent with the cert topping out at MCS 12-13); others may be
driver-only gaps. I plan to send a small ASK email separately covering
those questions before any follow-up patch series.

Louis Kotze (4):
  wifi: rtw89: advertise EML Capabilities and Restricted TWT for 8922a
  wifi: rtw89: advertise Multi-RU OFDMA receive for 8922a per WFA cert
  wifi: rtw89: advertise MLD TID-to-link mapping and link reconfiguration
  wifi: rtw89: advertise EHT OM Control for 8922a per WFA cert

 drivers/net/wireless/realtek/rtw89/core.c | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)

Louis Kotze (4):
  wifi: rtw89: advertise EML Capabilities and Restricted TWT for 8922a
  wifi: rtw89: advertise Multi-RU OFDMA receive for 8922a per WFA cert
  wifi: rtw89: advertise MLD TID-to-link mapping and link
    reconfiguration
  wifi: rtw89: advertise EHT OM Control for 8922a per WFA cert

 drivers/net/wireless/realtek/rtw89/core.c | 17 +++++++++++++----
 1 file changed, 13 insertions(+), 4 deletions(-)


base-commit: 7baf5857e15d722776898510a10546d6b2f18645
-- 
2.54.0