From: Russell King - ARM Linux admin <linux@armlinux.org.uk>
To: Andrew Lunn <andrew@lunn.ch>
Cc: David Miller <davem@davemloft.net>,
netdev <netdev@vger.kernel.org>,
Florian Fainelli <f.fainelli@gmail.com>,
ioana.ciornei@nxp.com, olteanv@gmail.com
Subject: Re: [PATCH net] net: dsa: Don't instantiate phylink for CPU/DSA ports unless needed
Date: Tue, 31 Mar 2020 13:57:18 +0100 [thread overview]
Message-ID: <20200331125718.GM25745@shell.armlinux.org.uk> (raw)
In-Reply-To: <20200311152424.18067-1-andrew@lunn.ch>
On Wed, Mar 11, 2020 at 04:24:24PM +0100, Andrew Lunn wrote:
> By default, DSA drivers should configure CPU and DSA ports to their
> maximum speed. In many configurations this is sufficient to make the
> link work.
>
> In some cases it is necessary to configure the link to run slower,
> e.g. because of limitations of the SoC it is connected to. Or back to
> back PHYs are used and the PHY needs to be driven in order to
> establish link. In this case, phylink is used.
>
> Only instantiate phylink if it is required. If there is no PHY, or no
> fixed link properties, phylink can upset a link which works in the
> default configuration.
>
> Fixes: 0e27921816ad ("net: dsa: Use PHYLINK for the CPU/DSA ports")
> Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Hi Andrew,
This seems to conflict with the serdes changes. For a CPU port using
a serdes connection, we claim the serdes interrupt, which then triggers
this:
[ 9.069631] Unable to handle kernel NULL pointer dereference at virtual address 00000124
[ 9.077785] pgd = c0004000
[ 9.080528] [00000124] *pgd=00000000
[ 9.084157] Internal error: Oops: 805 [#1] SMP ARM
[ 9.088961] Modules linked in: tag_edsa spi_nor mtd xhci_plat_hcd mv88e6xxx(+) xhci_hcd armada_thermal marvell_cesa dsa_core ehci_orion libdes phy_armada38x_comphy at24 mcp3021 sfp evbug spi_orion sff mdio_i2c
[ 9.107625] CPU: 1 PID: 214 Comm: irq/55-mv88e6xx Not tainted 5.6.0+ #470
[ 9.114429] Hardware name: Marvell Armada 380/385 (Device Tree)
[ 9.120371] PC is at phylink_mac_change+0x10/0x88
[ 9.125129] LR is at mv88e6352_serdes_irq_status+0x74/0x94 [mv88e6xxx]
which is because dp->pl is NULL in dsa_port_phylink_mac_change() as a
result of this commit for links operating at max speed without a
fixed-link property.
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTC broadband for 0.8mile line in suburbia: sync at 10.2Mbps down 587kbps up
prev parent reply other threads:[~2020-03-31 12:57 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-11 15:24 [PATCH net] net: dsa: Don't instantiate phylink for CPU/DSA ports unless needed Andrew Lunn
2020-03-12 0:24 ` Vladimir Oltean
2020-03-12 6:46 ` David Miller
2020-03-31 12:57 ` Russell King - ARM Linux admin [this message]
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