netdev - Re: lan78xx: /sys/class/net/eth0/carrier stuck at 1

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20201023130519.GB745568@lunn.ch>
Date:   Fri, 23 Oct 2020 15:05:19 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Juerg Haefliger <juerg.haefliger@...onical.com>
Cc:     netdev@...r.kernel.org, woojung.huh@...rochip.com
Subject: Re: lan78xx: /sys/class/net/eth0/carrier stuck at 1

On Fri, Oct 23, 2020 at 08:29:59AM +0200, Juerg Haefliger wrote:
> On Wed, 21 Oct 2020 21:35:48 +0200
> Andrew Lunn <andrew@...n.ch> wrote:
> 
> > On Wed, Oct 21, 2020 at 05:00:53PM +0200, Juerg Haefliger wrote:
> > > Hi,
> > > 
> > > If the lan78xx driver is compiled into the kernel and the network cable is
> > > plugged in at boot, /sys/class/net/eth0/carrier is stuck at 1 and doesn't
> > > toggle if the cable is unplugged and replugged.
> > > 
> > > If the network cable is *not* plugged in at boot, all seems to work fine.
> > > I.e., post-boot cable plugs and unplugs toggle the carrier flag.
> > > 
> > > Also, everything seems to work fine if the driver is compiled as a module.
> > > 
> > > There's an older ticket for the raspi kernel [1] but I've just tested this
> > > with a 5.8 kernel on a Pi 3B+ and still see that behavior.  
> > 
> > Hi Jürg
> 
> Hi Andrew,
> 
> 
> > Could you check if a different PHY driver is being used when it is
> > built and broken vs module or built in and working.
> > 
> > Look at /sys/class/net/eth0/phydev/driver
> 
> There's no such file.

I _think_ that means it is using genphy, the generic PHY driver, not a
specific vendor PHY driver? What does

/sys/class/net/eth0/phydev/phy_id contain.
  
> Given that all works fine as long as the cable is unplugged at boot points
> more towards a race at boot or incorrect initialization sequence or something.

Could be. Could you run

mii-tool -vv eth0

in the good and bad case.

   Andrew