mt7915 WED enabled router + Intel clients - strange behavior

[levshutov]

Redmi AX6S (mt7622 soc with mt7915) OpenWrt SNAPSHOT r21900-ac21dff5b6 (5.15.89 kernel) mt76 @ git commit 6fe2c2383d3d9e537661b96f974408ddd719dff1 WAN - 1GbE DHCP WLAN - AX 36ch 80MHz Enabled HW Offloading and WED

Wan network has iperf3 server.

Wireless client have normal 500+ Mb/s iperf3 download speed for several seconds. Then it drops less than 100 Mb/s for several seconds. Then everything repeats.

In case client and router have direct traffic (pinging each other or refreshing LuCI in browser) during iperf3 test - no speed drops.

Disabling HW Offloading and/or WED - no speed drops.

Issue occurs on Intel cards AX200, AX1675, Advanced-N 6235 in Win11.

Issue does not occur on Realtek RTL8852AE in Win11. Issue does not occur on Android/Iphone devices.

[lukasz1992]

Have you tried to update drivers (especially AX200) to the most recent version?

[levshutov]

Have you tried to update drivers (especially AX200) to the most recent version?

Tried old and new drivers by Intel and Microsoft.

[ryderlee1110]

Root cause of this interoperability issue - there's no any keep alive packet being received by host stack => leads to mac80211 timer timeout => destroys BA session

ax series needs to update timer for each 5s period to maintain ba session. We don't have a better solution for this, but you can give this change a try. This shouldn't affect anything.

--- a/net/mac80211/agg-tx.c
+++ b/net/mac80211/agg-tx.c
@@ -568,10 +568,9 @@ static void sta_tx_agg_session_timer_expired(struct timer_list *t)
    }

    timeout = tid_tx->last_tx + TU_TO_JIFFIES(tid_tx->timeout);
-   if (time_is_after_jiffies(timeout)) {
-       mod_timer(&tid_tx->session_timer, timeout);
-       return;
-   }
+   /* remove timerout handle for ax210 interoperability issue */
+   mod_timer(&tid_tx->session_timer, timeout);
+   return;

[levshutov]

Thanks. It works.

[ryderlee1110]

I think we can close this ticket.

@nbd168 just for your reference in case you have a better solution for upstream.

[nbd168]

This hack will not be accepted upstream, since it effectively completely disables the session expiry timer without removing the code. A better solution would be to allow the driver to refresh the timer, based on querying stats from the firmware.

[padavanonly]

Have you ever meet this issue with ax6s stock firmware ?

[levshutov]

Have you ever meet this issue with ax6s stock firmware ?

Didn't do much tests with stock firmware.

[ryderlee1110]

@levshutov could you help to test this patch https://pastebin.mozilla.org/mWZ5tLU6/raw?

[levshutov]

@levshutov could you help to test this patch https://pastebin.mozilla.org/mWZ5tLU6/raw?

It works.

[ryderlee1110]

We can close this ticket. I've posted to upstream. Maybe you can reply an acked-by or tested-by tag there.