[REGRESSION] rtw89_8852ae: HT/VHT/HE not negotiated, stuck at 54 Mbps since kernel 6.18

[REGRESSION] rtw89_8852ae: HT/VHT/HE not negotiated, stuck at 54 Mbps since kernel 6.18

[Chris Wituchowski]

*resend as plaintext - sent originally as html, sorry!*

Hi,

I'm reporting a regression in the rtw89_8852ae driver. After upgrading from
kernel 6.14.x (Fedora 42 GA) to 6.18.x (Fedora 43), my RTL8852AE WiFi adapter
no longer negotiates HT, VHT, or HE with the access point. The connection falls
back to legacy 802.11a at 54 Mbps on 5 GHz, delivering only ~20 Mbps real-world
throughput on a gigabit link.

== Hardware ==

  Adapter: Realtek RTL8852AE 802.11ax PCIe (WiFi 6, 2x2 MIMO)
  PCI ID:  10ec:8852 (subsystem: 17aa:4852, Lenovo)
  System:  Lenovo laptop

== Software ==

  Broken:   6.18.13-200.fc43.x86_64 (also 6.18.10, 6.18.12 — all broken)
  Last OK:  6.14.x (Fedora 42 GA kernel — WiFi worked at full 802.11ax speeds)
  Driver:   rtw89_8852ae (in-tree)
  Firmware: rtw8852a_fw.bin (v0.13.36.2 / 52acc807)
  Distro:   Fedora 43

== Symptoms ==

The adapter connects to a 5 GHz AP (channel 157) but fails to negotiate
HT/VHT/HE, falling back to legacy 20 MHz / 54 Mbps:

  $ iw dev wlp3s0 link
  Connected to 52:bb:9f:a2:d8:4a (on wlp3s0)
      SSID: Innernette
      freq: 5785.0
      signal: -29 dBm
      rx bitrate: 54.0 MBit/s
      tx bitrate: 54.0 MBit/s

  $ iw dev wlp3s0 info
      channel 157 (5785 MHz), width: 20 MHz (no HT), center1: 5785 MHz

Debugfs confirms the driver is not reporting any HT/VHT/HE capabilities
for the station:

  /sys/kernel/debug/ieee80211/phy*/netdev:wlp3s0/stations/<bssid>/ht:
      "ht not supported"

  /sys/kernel/debug/ieee80211/phy*/netdev:wlp3s0/stations/<bssid>/vht:
      "VHT not supported"

  /sys/kernel/debug/ieee80211/phy*/netdev:wlp3s0/stations/<bssid>/he:
      "HE not supported"

== AP Capabilities (confirmed via iw scan) ==

The AP fully supports HT, VHT, and HE:

  - HT: HT20/HT40, MCS 0-15 (2 spatial streams)
  - VHT: up to 80 MHz, MCS 0-9 for 2 SS
  - HE (WiFi 6): full 802.11ax support
  - Max advertised rate: 1170 Mbps

The AP's "HT protection" field shows "non-HT mixed mode", confirming it
sees the client as a non-HT legacy station.

== What I've Ruled Out ==

  1. Signal strength: Excellent (-27 to -48 dBm across tests)
  2. WPA3 vs WPA2: Same result with both (key-mgmt sae and psk)
  3. wpa_supplicant vs iwd: Same result with both backends
  4. Firmware: Already on latest version (v0.13.36.2)
  5. Driver reload: Full unload/reload of rtw89 module stack — no change
  6. Power save: Disabled (disable_ps_mode module parameter)
  7. wl module conflict: Blacklisted via /etc/modprobe.d/blacklist-wl.conf
  8. Regulatory: US domain active, DFS-FCC, correct for channel 157
  9. Regression within 6.18.x: Changelogs for 6.18.10→6.18.13 contain
     ZERO rtw89/mac80211/cfg80211 changes. Bug exists across all 6.18.x.

== Likely Cause ==

Between kernel 6.14 and 6.18, the rtw89 driver received hundreds of commits
for WiFi 7 MLO (Multi-Link Operation) support, including:

  - mac80211 per-link STA refactoring (HT/VHT/HE caps moved to per-link
    link_sta structures)
  - 54+ chanctx commits in rtw89 ("chan: manage active interfaces",
    "tweak setting of channel and TX power for MLO", etc.)
  - "disable EHT protocol by chip capabilities"

The RTL8852AE is a gen1 WiFi 6 chip. The MLO work was developed and tested
primarily on gen2 WiFi 7 chips (RTL8922A/E). It appears the gen1 code path
through the new per-link framework is not correctly populating HT/VHT/HE
capabilities during association.

== Steps to Reproduce ==

  1. System with RTL8852AE (10ec:8852) running kernel 6.18.x
  2. Connect to any 5 GHz 802.11ax access point
  3. Observe: iw dev <if> info shows "width: 20 MHz (no HT)"
  4. Observe: iw dev <if> link shows 54.0 MBit/s bitrate
  5. Observe: debugfs ht/vht/he files all report "not supported"

== Expected Result ==

Connection should negotiate HT/VHT/HE (80 MHz, WiFi 6) as it did on
kernel 6.14.x, providing 800+ Mbps link rates.

Thanks,
Chris

RE: [REGRESSION] rtw89_8852ae: HT/VHT/HE not negotiated, stuck at 54 Mbps since kernel 6.18

[Ping-Ke Shih]

Chris Wituchowski <flashrift@gmail.com> wrote:
> *resend as plaintext - sent originally as html, sorry!*
> 
> Hi,
> 
> I'm reporting a regression in the rtw89_8852ae driver. After upgrading from
> kernel 6.14.x (Fedora 42 GA) to 6.18.x (Fedora 43), my RTL8852AE WiFi adapter
> no longer negotiates HT, VHT, or HE with the access point. The connection falls
> back to legacy 802.11a at 54 Mbps on 5 GHz, delivering only ~20 Mbps real-world
> throughput on a gigabit link.
> 
> == Hardware ==
> 
>   Adapter: Realtek RTL8852AE 802.11ax PCIe (WiFi 6, 2x2 MIMO)
>   PCI ID:  10ec:8852 (subsystem: 17aa:4852, Lenovo)
>   System:  Lenovo laptop
> 
> == Software ==
> 
>   Broken:   6.18.13-200.fc43.x86_64 (also 6.18.10, 6.18.12 — all broken)
>   Last OK:  6.14.x (Fedora 42 GA kernel — WiFi worked at full 802.11ax speeds)
>   Driver:   rtw89_8852ae (in-tree)
>   Firmware: rtw8852a_fw.bin (v0.13.36.2 / 52acc807)
>   Distro:   Fedora 43
> 
> == Symptoms ==
> 
> The adapter connects to a 5 GHz AP (channel 157) but fails to negotiate
> HT/VHT/HE, falling back to legacy 20 MHz / 54 Mbps:
> 
>   $ iw dev wlp3s0 link
>   Connected to 52:bb:9f:a2:d8:4a (on wlp3s0)
>       SSID: Innernette
>       freq: 5785.0
>       signal: -29 dBm
>       rx bitrate: 54.0 MBit/s
>       tx bitrate: 54.0 MBit/s
> 
>   $ iw dev wlp3s0 info
>       channel 157 (5785 MHz), width: 20 MHz (no HT), center1: 5785 MHz
> 
> Debugfs confirms the driver is not reporting any HT/VHT/HE capabilities
> for the station:
> 
>   /sys/kernel/debug/ieee80211/phy*/netdev:wlp3s0/stations/<bssid>/ht:
>       "ht not supported"
> 
>   /sys/kernel/debug/ieee80211/phy*/netdev:wlp3s0/stations/<bssid>/vht:
>       "VHT not supported"
> 
>   /sys/kernel/debug/ieee80211/phy*/netdev:wlp3s0/stations/<bssid>/he:
>       "HE not supported"
> 
> == AP Capabilities (confirmed via iw scan) ==
> 
> The AP fully supports HT, VHT, and HE:
> 
>   - HT: HT20/HT40, MCS 0-15 (2 spatial streams)
>   - VHT: up to 80 MHz, MCS 0-9 for 2 SS
>   - HE (WiFi 6): full 802.11ax support
>   - Max advertised rate: 1170 Mbps
> 
> The AP's "HT protection" field shows "non-HT mixed mode", confirming it
> sees the client as a non-HT legacy station.
> 
> == What I've Ruled Out ==
> 
>   1. Signal strength: Excellent (-27 to -48 dBm across tests)
>   2. WPA3 vs WPA2: Same result with both (key-mgmt sae and psk)
>   3. wpa_supplicant vs iwd: Same result with both backends
>   4. Firmware: Already on latest version (v0.13.36.2)
>   5. Driver reload: Full unload/reload of rtw89 module stack — no change
>   6. Power save: Disabled (disable_ps_mode module parameter)
>   7. wl module conflict: Blacklisted via /etc/modprobe.d/blacklist-wl.conf
>   8. Regulatory: US domain active, DFS-FCC, correct for channel 157
>   9. Regression within 6.18.x: Changelogs for 6.18.10→6.18.13 contain
>      ZERO rtw89/mac80211/cfg80211 changes. Bug exists across all 6.18.x.
> 
> == Likely Cause ==
> 
> Between kernel 6.14 and 6.18, the rtw89 driver received hundreds of commits
> for WiFi 7 MLO (Multi-Link Operation) support, including:
> 
>   - mac80211 per-link STA refactoring (HT/VHT/HE caps moved to per-link
>     link_sta structures)

That should be compatible with WiFi 6 and earlier. 

>   - 54+ chanctx commits in rtw89 ("chan: manage active interfaces",
>     "tweak setting of channel and TX power for MLO", etc.)

This driver is to support WiFi 6/7 chips. The WiFi 6 chips should work
as before these patches. 

>   - "disable EHT protocol by chip capabilities"

EHT is used WiFi 7 chips, so no worries about this.

> 
> The RTL8852AE is a gen1 WiFi 6 chip. The MLO work was developed and tested
> primarily on gen2 WiFi 7 chips (RTL8922A/E). It appears the gen1 code path
> through the new per-link framework is not correctly populating HT/VHT/HE
> capabilities during association.
> 
> == Steps to Reproduce ==
> 
>   1. System with RTL8852AE (10ec:8852) running kernel 6.18.x

I tried two kernel 6.18.1 and 6.19.3 with same firmware 0.13.36.2 (52acc807)
that both work with HE rates.

I did connection by 'iw connect' command instead, because my AP is non-secure. 

>   2. Connect to any 5 GHz 802.11ax access point
>   3. Observe: iw dev <if> info shows "width: 20 MHz (no HT)"

This is the output in my side:

        channel 36 (5180 MHz), width: 80 MHz, center1: 5210 MHz

>   4. Observe: iw dev <if> link shows 54.0 MBit/s bitrate

This is the output in my office (the rate isn't good, but still HE rate)

        rx bitrate: 600.4 MBit/s 80MHz HE-MCS 11 HE-NSS 1 HE-GI 0 HE-DCM 0
        tx bitrate: 183.7 MBit/s 80MHz HE-MCS 2 HE-NSS 2 HE-GI 2 HE-DCM 0

>   5. Observe: debugfs ht/vht/he files all report "not supported"

This is the output in stations/<bssid>/ directory:

$ sudo cat *capa | grep supported
EHT not supported
HE supported
ht supported
VHT supported

> 
> == Expected Result ==
> 
> Connection should negotiate HT/VHT/HE (80 MHz, WiFi 6) as it did on
> kernel 6.14.x, providing 800+ Mbps link rates.
> 

I don't have a Fedora on hand, and I tested above by Ubuntu + updated pre-built
kernel [1]. Please try if Ubuntu with 6.18.1 or 6.19.3 kernel can work in your side.

[1] https://kernel.ubuntu.com/mainline/v6.19.3/