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Date:   Sat, 25 Nov 2023 04:56:20 +0000
From:   Daniel Golle <daniel@makrotopia.org>
To:     Russell King <linux@armlinux.org.uk>, Andrew Lunn <andrew@lunn.ch>,
        Heiner Kallweit <hkallweit1@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Marek =?iso-8859-1?Q?Beh=FAn?= <kabel@kernel.org>,
        Pali =?iso-8859-1?Q?Roh=E1r?= <pali@kernel.org>,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Eric Woudstra <ericwouds@gmail.com>,
        John Crispin <john@phrozen.org>
Subject: [PATCH net] net: phylink: set phy_state interface when attaching SFP
Message-ID: <8abed37d01d427bf9d27a157860c54375c994ea1.1700887953.git.daniel@makrotopia.org>
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Assume 'usxgmii' being set as initial interface mode in DTS. Now plug
a 2.5GBase-T SFP module with exposed PHY. Currently this results in
a rather bizare situation:

RTL8221B-VB-CG 2.5Gbps PHY (C45) i2c:sfp1-wan:11: rtl822x_c45_get_features: supported=00,00000000,00008000,000080ef
mtk_soc_eth 15100000.ethernet eth2: requesting link mode phy/2500base-x with support 00,00000000,00008000,0000e0ef
mtk_soc_eth 15100000.ethernet eth2: switched to phy/2500base-x link mode   <<< !!!!!!
mtk_soc_eth 15100000.ethernet eth2: major config usxgmii    <<< !!!!!!
mtk_soc_eth 15100000.ethernet eth2: phylink_mac_config: mode=phy/usxgmii/none adv=00,00000000,00000000,00000000 pause=00
mtk_soc_eth 15100000.ethernet eth2: PHY [i2c:sfp1-wan:11] driver [RTL8221B-VB-CG 2.5Gbps PHY (C45)] (irq=POLL)
mtk_soc_eth 15100000.ethernet eth2: phy: 2500base-x setting supported 00,00000000,00008000,0000e0ef advertising 00,00000000,00008000,0000e0ef

Then the link seemingly comes up (but is dead) because no subsequent
call to phylink_major_config actually configured MAC and PCS for
2500base-x mode.

This is because phylink_mac_initial_config() considers
pl->phy_state.interface if in MLO_AN_PHY mode while
phylink_sfp_set_config() only sets pl->link_config.interface.

Also set pl->phy_state.interface in phylink_sfp_set_config().

Fixes: 31eb8907aa5b ("net: phylink: allow attaching phy for SFP modules on 802.3z mode")
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
---
 drivers/net/phy/phylink.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index aa842634d5c2c..21ef77e4fe720 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -3056,6 +3056,7 @@ static void phylink_sfp_set_config(struct phylink *pl, u8 mode,
 	    pl->link_config.interface != state->interface) {
 		pl->cur_link_an_mode = mode;
 		pl->link_config.interface = state->interface;
+		pl->phy_state.interface = state->interface;
 
 		changed = true;
 
-- 
2.42.1