Re: [PATCH net-next v2 1/3] net: macb: fix SGMII with inband aneg disabled

[Conor Dooley]

On Wed, Mar 04, 2026 at 06:39:38PM +0000, Russell King (Oracle) wrote:
> > > > > Also '#define DEBUG' in 'drivers/net/phy/phylink.c' can help if you can
> > > > > recompile your kernel.
> > > > 
> > > > Setting this provided no further logs, seemingly.
> > > 
> > > It certainly would if you place it before the first #include - I
> > > routinely build kernels with it set as such. The messages are produced
> > > at debug level, so should appear via "dmesg". If you want to see them
> > > on the console, you need to add "debug" to the kernel command line.
> > 
> > Clearly I'm too stupid for this, because I did it again and still got no
> > more logs. I even disabled DYNAMIC_DEBUG since that has an interaction
> > in the file.
> 
> I'm sorry, I don't know what's going on there. As I say, it works for
> me. E.g. from two days ago:

Thinking about it now, it's just because the codepaths that I took in the
phy subsystem in the error case just didn't produce any logs.
Adding it does produce more logs in a working system.

> 
> [  101.279224] mvneta f1034000.ethernet eno2: configuring for inband/2500base-x link mode
> [  101.287194] mvneta f1034000.ethernet eno2: major config, requested inband/2500base-x
> [  101.294986] mvneta f1034000.ethernet eno2: interface 2500base-x inband modes: pcs=02 phy=00
> [  101.303423] mvneta f1034000.ethernet eno2: major config, active inband/inband,an-enabled/2500base-x
> [  101.312541] mvneta f1034000.ethernet eno2: phylink_mac_config: mode=inband/2500base-x/none adv=00000000,00000000,00008000,0000a240 pause=04
> [  101.325123] mvneta f1034000.ethernet eno2: pcs link down
> ...
> [  101.447124] mvneta f1034000.ethernet eno2: phylink_sfp_connect_phy()
> [  101.453541] mvneta f1034000.ethernet eno2: copper SFP: interfaces=[mac=4,9-12,19,22-23, sfp=4,23,27]
> [  101.462789] mvneta f1034000.ethernet eno2: copper SFP: chosen 2500base-x interface
> [  101.470563] mvneta f1034000.ethernet eno2: PHY i2c:sfp:16 uses interfaces 4,23,27, validating 4,23
> [  101.479636] mvneta f1034000.ethernet eno2:  interface 4 (sgmii) rate match none supports 2-3,5-6,13
> [  101.488730] mvneta f1034000.ethernet eno2:  interface 23 (2500base-x) rate match none supports 6,13,47
> [  101.498079] mvneta f1034000.ethernet eno2: PHY [i2c:sfp:16] driver [Broadcom BCM84881] (irq=POLL)
> [  101.507043] mvneta f1034000.ethernet eno2: phy: 2500base-x setting supported 00000000,00000000,00008000,0000206c advertising 00000000,00000000,00008000,0000206c
> [  101.522979] mvneta f1034000.ethernet eno2: major config, requested inband/2500base-x
> [  101.530778] mvneta f1034000.ethernet eno2: interface 2500base-x inband modes: pcs=02 phy=01
> [  101.539213] mvneta f1034000.ethernet eno2: 2500base-x: incompatible in-band capabilities, trying in-band
> [  101.548732] mvneta f1034000.ethernet eno2: major config, active inband/inband,an-enabled/2500base-x
> [  101.557842] mvneta f1034000.ethernet eno2: phylink_mac_config: mode=inband/2500base-x/none adv=00000000,00000000,00008000,0000206c pause=04
> [  101.570425] mvneta f1034000.ethernet eno2: phylink_sfp_module_start()
> [  101.576903] mvneta f1034000.ethernet eno2: phylink_sfp_link_up()
> [  101.692254] mvneta f1034000.ethernet eno2: phy link down 2500base-x/Unknown/Unknown/none/off/nolpi
> 
> with the following at the top of phylink.c:
> 
> // SPDX-License-Identifier: GPL-2.0
> /*
>  * phylink models the MAC to optional PHY connection, supporting
>  * technologies such as SFP cages where the PHY is hot-pluggable.
>  *
>  * Copyright (C) 2015 Russell King
>  */
> #define DEBUG
> #include <linux/acpi.h>
> ...
> 
> -- 
> RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
> FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!

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