RE: [EXT] Re: [PATCH net] net: phylink: fix link state on phy-connect

[Yan Markman]

Hi Russel

On my board I have [Marvell 88E1510] phy working with STATUS-POLLING
I see some inconsistencies  -- first ifconfig-up is different from furthers, no "link is down" reports.
Please refer the behavior example below.
My patch is a "simple solution"  -- always reset/clear Link-state-parameters before going UP.
Possibly, more correct (but much more complicated) solution would be in the   phy state machine   and   phylink resolve modification.
I just found that 
    On ifconfig-down, the phy-state-machine and phylink-resolve
    are stopped before executing before passing over full graceful down/reset state.
    The further ifconfig-up starts with old state parameters.
Special cases not-tested but logic 2 test-cases are:
   remote side changes speed whilst link is Down or Disconnected. But local ifconfig-up starts with old speed.

Best regards
Yan Markman
----------------------------------------------------
EXAMPLE:
buildroot login: root
~# ifconfig eth1 192.169.0.81 up
[   34.072042] mvpp2 f2000000.ethernet eth1: PHY [f212a200.mdio-mii:01] driver [Marvell 88E1510]
[   34.080654] mvpp2 f2000000.ethernet eth1: configuring for phy/rgmii-id link mode
[   37.220506] mvpp2 f2000000.ethernet eth1: Link is Up - 1Gbps/Full - flow control off

~# ifconfig eth1 down
          No print "link is down"

~# ifconfig eth1 up
          "Link is Up" passed twice:
[   60.748041] mvpp2 f2000000.ethernet eth1: PHY [f212a200.mdio-mii:01] driver [Marvell 88E1510]
[   60.756653] mvpp2 f2000000.ethernet eth1: configuring for phy/rgmii-id link mode
[   60.764169] mvpp2 f2000000.ethernet eth1: Link is Up - 1Gbps/Full - flow control off
[   63.908504] mvpp2 f2000000.ethernet eth1: Link is Up - 1Gbps/Full - flow control off

On Link physical disconnect/break 
          No print "link is down"
          But link is in correct state --   ifconfig UP but not-RUNNING
On Link physical re-connect
[   84.388501] mvpp2 f2000000.ethernet eth1: Link is Up - 1Gbps/Full - flow control off
-------------------------------------------------------------------------------------------
YAN's findings:


Best regards
Yan Markman

-----Original Message-----
From: Russell King [mailto:rmk@xxxxxxxxxxxxxxx] 
Sent: Tuesday, November 28, 2017 5:56 PM
To: Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
Cc: andrew@xxxxxxx; f.fainelli@xxxxxxxxx; davem@xxxxxxxxxxxxx; Yan Markman <ymarkman@xxxxxxxxxxx>; gregory.clement@xxxxxxxxxxxxxxxxxx; thomas.petazzoni@xxxxxxxxxxxxxxxxxx; miquel.raynal@xxxxxxxxxxxxxxxxxx; Nadav Haklai <nadavh@xxxxxxxxxxx>; mw@xxxxxxxxxxxx; Stefan Chulski <stefanc@xxxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
Subject: [EXT] Re: [PATCH net] net: phylink: fix link state on phy-connect

External Email

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Oh, and lastly, please send patches to linux@xxxxxxxxxxxxxxx or the address I use in the sign-offs - sending them to rmk@xxxxxxxxxxxxxxx is for personal non-Linux mail only, and has resulted in _all_ of these messages ending up in my spam folder.

Thanks.

On Tue, Nov 28, 2017 at 03:53:17PM +0000, Russell King wrote:
> On Tue, Nov 28, 2017 at 02:29:32PM +0100, Antoine Tenart wrote:
> > From: Yan Markman <ymarkman@xxxxxxxxxxx>
> 
> Hi, thanks for the patch.
> 
> > When calling successively _connect, _disconnect and _connect again, 
> > if the link configuration changed whilst being down from the phylink 
> > perspective, the last _connect would stay in an incorrect old speed.
> > Fixes this by setting the link configuration parameters to an 
> > unknown value when calling phylink_bringup_phy.
> 
> Under what circumstances does this occur?
> 
> > 
> > Fixes: 9525ae83959b ("phylink: add phylink infrastructure")
> > Signed-off-by: Yan Markman <ymarkman@xxxxxxxxxxx>
> > [Antoine: commit message]
> > Signed-off-by: Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
> > ---
> >  drivers/net/phy/phylink.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> > 
> > diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c 
> > index e3bbc70372d3..c2cec3eef67d 100644
> > --- a/drivers/net/phy/phylink.c
> > +++ b/drivers/net/phy/phylink.c
> > @@ -621,6 +621,16 @@ static int phylink_bringup_phy(struct phylink *pl, struct phy_device *phy)
> >  	if (ret)
> >  		return ret;
> >  
> > +	/* On _disconnect, the phy state machine and phylink resolve
> > +	 * are stopped before executing full gracefull down/reset state.
> > +	 * The further _connect starts with incorrect init state. Let's set
> > +	 * init values here.
> > +	 */
> > +	pl->phy_state.link = false;
> > +	pl->link_config.pause = MLO_PAUSE_AN;
> > +	pl->link_config.speed = SPEED_UNKNOWN;
> > +	pl->link_config.duplex = DUPLEX_UNKNOWN;
> 
> It would be much better to clean up the phy_state in
> phylink_disconnect_phy() and trigger a resolve, rather than doing that 
> each time a PHY is connected - the link should be taken down when the 
> PHY is removed.
> 
> However, I'd like to know under what circumstances this is happening, 
> since, if you're hotplugging a PHY you should be doing that via SFP 
> which has additional link up/down handling.  What board is this with?
> 
> Also note that there's a number of patches in my "phy" branch that I'm 
> intending to send as a result of working with Florian over the last 
> few weeks.  There's several people working fairly independently in 
> this area and having everyone send patches independently of each other 
> could get painful to manage.
> 
> I'm intending to send patches once I know that net-next is open.
> 
> --
> Russell King
> ARM architecture Linux Kernel maintainer

--
Russell King
ARM architecture Linux Kernel maintainer