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SubjectRe: [PATCH] net: marvell: mvpp2: phylink requires the link interrupt
On Fri, Dec 13, 2019 at 04:34:03PM -0800, Jakub Kicinski wrote:
> On Tue, 10 Dec 2019 22:33:05 +0000, Russell King wrote:
> > phylink requires the MAC to report when its link status changes when
> > operating in inband modes. Failure to report link status changes
> > means that phylink has no idea when the link events happen, which
> > results in either the network interface's carrier remaining up or
> > remaining permanently down.
> >
> > For example, with a fiber module, if the interface is brought up and
> > link is initially established, taking the link down at the far end
> > will cut the optical power. The SFP module's LOS asserts, we
> > deactivate the link, and the network interface reports no carrier.
> >
> > When the far end is brought back up, the SFP module's LOS deasserts,
> > but the MAC may be slower to establish link. If this happens (which
> > in my tests is a certainty) then phylink never hears that the MAC
> > has established link with the far end, and the network interface is
> > stuck reporting no carrier. This means the interface is
> > non-functional.
> >
> > Avoiding the link interrupt when we have phylink is basically not
> > an option, so remove the !port->phylink from the test.
> >
> > Tested-by: Sven Auhagen <sven.auhagen@voleatech.de>
> > Tested-by: Antoine Tenart <antoine.tenart@bootlin.com>
> > Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
>
> Fixes: 4bb043262878 ("net: mvpp2: phylink support") ?
>
> Seems like you maybe didn't want this backported to stable hence
> no fixes tag?

Correct, because backporting just this patch will break the
Macchiatobin.

This patch is dependent on the previous two patches, which are more
about correct use of the API. I suspect if you try to backport the
series, things will get very hairly very quickly.

>
> Please advise :)
>
> > diff --git a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > index 111b3b8239e1..ef44c6979a31 100644
> > --- a/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > +++ b/drivers/net/ethernet/marvell/mvpp2/mvpp2_main.c
> > @@ -3674,7 +3674,7 @@ static int mvpp2_open(struct net_device *dev)
> > valid = true;
> > }
> >
> > - if (priv->hw_version == MVPP22 && port->link_irq && !port->phylink) {
> > + if (priv->hw_version == MVPP22 && port->link_irq) {
> > err = request_irq(port->link_irq, mvpp2_link_status_isr, 0,
> > dev->name, port);
> > if (err) {
>
>

--
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