Public bug reported:
Release: Ubuntu 26.04.1 LTS (Kubuntu), via lsb_release -rd Package:
linux-image-7.0.0-38-generic 7.0.0-38.38 (version signature "Ubuntu
7.0.0-38.38-generic 7.0.14", see version.log)
What I expected to happen: A Qualcomm WCN7850 (WCN785x) Wi-Fi 7 card
connects to a Wi-Fi 7 router with MLO (5 GHz + 6 GHz links) and gets an
IP address and working traffic.
What happened instead: The card associates (wpa_supplicant reports CTRL-
EVENT-CONNECTED with ap_mld_addr) but no data flows: DHCP never
completes (45 s timeout) and the kernel repeatedly logs ath12k_wifi7_pci
0000:11:00.0: dp_tx: failed to find the peer with peer_id 8193 (8193 =
0x2001, an ML peer id). It fails only when two MLO links are associated
at once: with wpa_supplicant alone, every attempt that set up two links
(5 GHz + 6 GHz) failed (3/3, see link-correlation-7.0.0-38.txt), and
every attempt with a single link worked (4/4). A packet capture during a
failure shows DHCP Requests leaving the card and no reply, while AP
broadcast frames are received. Overall 3 failures out of 6 connection
attempts. iwd (plain association, no MLO) is stable.
Hardware: MSI PRO X870E-P WIFI (MS-7E70), BIOS 2.A52, Ryzen 7 9800X3D.
PCI 17cb:1107 (subsystem 105b:e0f7), driver ath12k_wifi7_pci. Firmware:
WLAN.HMT.1.1.c7-00108-QCAHMTSWPL_V1.0_V2.0_SILICONZ_UPSTREAM-3
(2026-03-06), linux-firmware 20260319.git217ca6e4. Userspace:
wpa_supplicant 2.11, NetworkManager 1.54.3. Access point: Mercusys Wi-Fi
7 router (BE9300). The same router works with a MediaTek MT7925
(mt7925e), two Pixel phones and a Wi-Fi 6 laptop.
Result on mainline 7.2.6 (Ubuntu mainline build, same firmware and
userspace): two links associated (5 GHz ch36 80 MHz + 6 GHz ch37 320
MHz), 150/150 pings, 5/5 forced reconnections OK (2 of them with two
links), no peer_id error and no kernel WARNING.
Upstream fix: series "wifi: ath12k: support firmware-allocated MLD peer
ID" (Baochen Qiang, July 2026), present in v7.2. Its description says
that WCN7850/QCC2072 firmware picks the MLD peer ID itself, so
dp_peers[] is never populated for MLO peers and the data path lookup
fails. Commits (in v7.2): a7619b3 wifi: ath12k: defer dp_peer
registration when firmware allocates MLD peer ID 469d7e6 wifi: ath12k:
resolve PENDING ML peer ID from MLO_PEER_MAP HTT event a08455e wifi:
ath12k: do not advertise MLD peer ID for firmware-allocate devices
dd121ed wifi: ath12k: keep ATH12K_PEER_ML_ID_VALID set in
ath12k_sta::ml_peer_id Also in v7.2: 51d510589f5c "wifi: ath12k: allow
peer_id 0 in dp peer lookup", a2fe9dc "wifi: ath12k: Fix low MLO RX
throughput on WCN7850". Only in v7.3-rc3: 01cc0f5 "wifi: ath12k: fix MLO
peer delete race", "skip MLO multicast links during crash recovery in Tx
path". On 7.0.0-38 I also saw one firmware crash and recovery while
cycling connections (AMD-Vi IO_PAGE_FAULT, "Timeout in receiving peer
delete response", ath12k_core_restart with WARNINGs).
Request: please consider backporting the commits above to the 26.04
kernel (7.0.y), or tell me if the 26.04 HWE kernel will include them.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: ath12k mlo resolute wifi
** Attachment added: "attachments.zip"
https://bugs.launchpad.net/bugs/2170059/+attachment/6007221/+files/attachments.zip
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https://bugs.launchpad.net/bugs/2170059
Title:
ath12k (WCN7850): MLO with two links gets no DHCP/data on 7.0.0-38
("failed to find the peer with peer_id 8193"); fixed upstream in 7.2
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