Re: [PATCH 4/5] arm64: dts: renesas: r9a09g077: Switch GBETH TX queue scheduling to WRR

[Geert Uytterhoeven]

On Wed, 22 Jul 2026 at 10:55, Ovidiu Panait
<ovidiu.panait.rb@xxxxxxxxxxx> wrote:
> The GBETH ethernet nodes don't specify a TX scheduling policy, so stmmac
> falls back to Strict Priority. In this configuration the queue with the
> highest priority gets all the traffic, starving the others under load.
>
> Under sustained UDP TX load with multiple data streams, this starvation
> triggers spurious adapter resets due to TX queue timeouts:
>
>   iperf3 -c <ip> -i0 -t60 --bind-dev end0 -u -b0 -P4
>   end0: NETDEV WATCHDOG: CPU: 1: transmit queue 1 timed out 5228 ms
>   end0: Reset adapter.
>
> Investigation shows that only the highest priority queue is advancing
> while the others stall for more than 5 seconds, causing a netdev watchdog
> reset.
>
> Switch the TX scheduling policy to Weighted-Round-Robin (WRR) so that
> traffic is processed across all queues, eliminating the stalls.
>
> Fixes: 394c1e24a4cf ("arm64: dts: renesas: r9a09g077: Add GMAC nodes")
> Signed-off-by: Ovidiu Panait <ovidiu.panait.rb@xxxxxxxxxxx>

LGTM, so
Reviewed-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
i.e. will queue in renesas-devel for v7.4.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds