Sorry, just discovered that it appears you all already know about this. Claude Opus 5 Ultracode couldn't find it until I asked about the 7.2RC's.
_______________________ Upstream fix identified. Root cause: on WCN7850 there is only a single "ar" instance, but MLO uses two link IDs. ath12k_dp_peer->hw_links[] is indexed by ar->hw_link_id, so both MLO link IDs land in the same slot, and ath12k_dp_rx_deliver_msdu() assigns an incorrect link ID to MSDUs. Result is severe MLO RX throughput loss -- which matches this report exactly (RX 332 Mbps on the working kernel vs 4.15 Mbps on 7.0, with elevated "rx drop misc"). Fixed upstream by: commit a2fe9dc70f3b8d5716fbcfed5fbfb9cf3948d402 "wifi: ath12k: Fix low MLO RX throughput on WCN7850" Author: Yingying Tang <[email protected]> Fixes: 11157e0910fd ("wifi: ath12k: Use ath12k_dp_peer in per packet Tx & Rx paths") Link: https://patch.msgid.link/[email protected] Path into mainline: ath-current -> tag ath-current-20260713 -> net-7.2-rc5. First tagged release containing it: v7.2-rc5. Affected range (checked by commit ancestry, not by changelog): - 11157e0910fd is NOT in v6.19 and IS in v7.0, so v7.0 is the first affected release. This is consistent with 6.17.0-41-generic and 6.18.40 being unaffected. - v7.1 does not contain the fix (v7.1 is an ancestor of a2fe9dc70f3b). - linux-7.1.y does not contain the fix as of the 2026-07-24 batch. This confirms my earlier note that no workaround exists on 7.0: the fault is in the RX data path itself, and blacklisting ath12k_wifi7 only leaves the device with no driver at all. Request: please consider cherry-picking a2fe9dc70f3b into the 26.04 (Resolute Raccoon) 7.0 kernel, both the generic and OEM flavours. The commit carries no "Cc: stable", so it will not reach 7.0 via the usual upstream stable flow, and upstream 7.0.y is no longer listed on kernel.org. The change is self-contained in ath12k (73 insertions, 7 deletions across dp_peer.c/.h, dp_rx.c, hw.h, mac.c and wifi7/dp_rx.c|.h, wifi7/hw.c) and adds a new hw_op set_rx_link_id() so the QCN9274/IPQ5332 data path is unchanged. Note that the commit's Tested-on line is: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00302-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.115823.3 Affected hardware: Qualcomm WCN785x Wi-Fi 7 (802.11be) 320MHz 2x2 [FastConnect 7800] PCI 17cb:1107, subsystem 105b:e0f7 ath12k_wifi7_pci, "Wi-Fi 7 Hardware name: wcn7850 hw2.0" MLO active on 2.4/5/6 GHz, 320 MHz, EHT-MCS 9 / NSS 2 Firmware: WLAN.HMT.1.1.c5-00302-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1.115823.3 ** Summary changed: - Ubuntu Studio 26.04 + [ath12k WCN7850] MLO RX throughput collapses ~80x on kernel 7.0 (fixed upstream in 7.2-rc5) -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2162545 Title: [ath12k WCN7850] MLO RX throughput collapses ~80x on kernel 7.0 (fixed upstream in 7.2-rc5) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2162545/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
