From: Simon Horman <horms@kernel.org>
To: Florian Fainelli <florian.fainelli@broadcom.com>
Cc: netdev@vger.kernel.org, "Jonas Gorski" <jonas.gorski@gmail.com>,
"Andrew Lunn" <andrew@lunn.ch>,
"Vladimir Oltean" <olteanv@gmail.com>,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@kernel.org>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Rafał Miłecki" <rafal@milecki.pl>,
"Broadcom internal kernel review list"
<bcm-kernel-feedback-list@broadcom.com>,
"Jon Mason" <jon.mason@broadcom.com>,
"Arnd Bergmann" <arnd@arndb.de>,
"open list" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH net v4 1/2] net: ethernet: bgmac: preserve forced 2.5 Gbps link speed
Date: Tue, 3 Nov 2026 11:21:58 +0000 [thread overview]
Message-ID: <20261103112158.GF865646@horms.kernel.org> (raw)
In-Reply-To: <20261029211540.4123250-2-florian.fainelli@broadcom.com>
On Thu, Oct 29, 2026 at 02:15:39PM -0700, Florian Fainelli wrote:
> Northstar and Northstar Plus use a 2.5 Gbps internal link between the
> AMAC and the switch. BGMAC_FEAT_FORCE_SPEED_2500 makes bgmac_miiconfig()
> configure that speed, but bgmac_adjust_link() subsequently replaces it
> with the synthetic fixed PHY's 1 Gbps speed.
>
> Use the forced speed when processing link changes so the MAC remains at
> 2.5 Gbps. Together with configuring the switch IMP port for its 2 Gbps
> mode, this eliminates the output queue discards that caused approximately
> 1000 TCP retransmissions per second during an iperf3 transmit test.
>
> Restrict the platform forced-speed flag to Northstar Plus using the SoC
> compatible, since Hurricane2 shares the AMAC compatible. Other platform
> AMACs without a phy-handle must continue following the fixed PHY speed.
> The BCMA path already selects the flag only for the Northstar family.
>
> Fixes: f6a95a24957a ("net: ethernet: bgmac: Add platform device support")
> Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Simon Horman <horms@kernel.org>
next prev parent reply other threads:[~2026-11-03 11:22 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-29 21:15 [PATCH net v4 0/2] Fix TCP retransmissions on NS/NSP SoCs Florian Fainelli
2026-10-29 21:15 ` [PATCH net v4 1/2] net: ethernet: bgmac: preserve forced 2.5 Gbps link speed Florian Fainelli
2026-11-02 21:50 ` netdev-bot+sashiko
2026-11-02 23:24 ` Florian Fainelli
2026-11-03 11:21 ` Simon Horman [this message]
2026-10-29 21:15 ` [PATCH net v4 2/2] net: dsa: b53: restore the NSP IMP port 2 Gbps mode Florian Fainelli
2026-11-02 21:50 ` netdev-bot+sashiko
2026-11-02 23:25 ` Florian Fainelli
2026-11-03 11:22 ` Simon Horman
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