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net: ethernet: bgmac: preserve forced 2.5 Gbps link speed

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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: f6a95a2495 ("net: ethernet: bgmac: Add platform device support")
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20261029211540.4123250-2-florian.fainelli@broadcom.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
This commit is contained in:
Florian Fainelli 2026-10-29 14:15:39 -07:00 committed by Paolo Abeni
parent a75facf4bb
commit d4f3d2c046
2 changed files with 8 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
drivers/net/ethernet/broadcom/bgmac-platform.c
View File

@ -243,7 +243,8 @@ static int bgmac_probe(struct platform_device *pdev)
bgmac->phy_connect = platform_phy_connect;
} else {
bgmac->phy_connect = bgmac_phy_connect_direct;
bgmac->feature_flags |= BGMAC_FEAT_FORCE_SPEED_2500;
if (of_machine_is_compatible("brcm,nsp"))
bgmac->feature_flags |= BGMAC_FEAT_FORCE_SPEED_2500;
}
return bgmac_enet_probe(bgmac);

8
drivers/net/ethernet/broadcom/bgmac.c
View File

@ -1430,11 +1430,15 @@ void bgmac_adjust_link(struct net_device *net_dev)
{
struct bgmac *bgmac = netdev_priv(net_dev);
struct phy_device *phy_dev = net_dev->phydev;
int speed = phy_dev->speed;
bool update = false;
if (bgmac->feature_flags & BGMAC_FEAT_FORCE_SPEED_2500)
speed = SPEED_2500;
if (phy_dev->link) {
if (phy_dev->speed != bgmac->mac_speed) {
bgmac->mac_speed = phy_dev->speed;
if (speed != bgmac->mac_speed) {
bgmac->mac_speed = speed;
update = true;
}