Re: [PATCH net v4 2/2] net: dsa: b53: restore the NSP IMP port 2 Gbps mode

[Simon Horman]

On Thu, Oct 29, 2026 at 02:15:40PM -0700, Florian Fainelli wrote:
> The Northstar Plus IMP port uses the switch's proprietary 2 Gbps mode for
> its internal link to the AMAC.  Its fixed-link description reports 1 Gbps,
> so applying that speed clears PORT_OVERRIDE_SPEED_2000M and leaves the two
> ends of the internal link configured at different speeds.
> 
> Force the 2 Gbps mode and flow control for BCM5301x and NSP CPU ports.  The
> mismatch caused switch output queue discards on both copper and SerDes
> ports, with one discard for every TCP retransmission.  With both ends
> restored to their high-speed modes, iperf3 reports no retransmissions.
> 
> Fixes: b6a8a5477fe9 ("net: dsa: b53: fix resetting speed and pause on forced link")
> Signed-off-by: Florian Fainelli <florian.fainelli@xxxxxxxxxxxx>

Reviewed-by: Simon Horman <horms@xxxxxxxxxx>