Hi Heiner,
On Wed, 27 Feb 2019 20:55:22 +0100, Heiner Kallweit <[email protected]>
wrote:
> When debugging another issue I faced an interrupt storm in this
> driver (88E6390, port 9 in SGMII mode), consisting of alternating
> link-up / link-down interrupts. Analysis showed that the driver
> wanted to set a cmode that was set already. But so far
> mv88e6390x_port_set_cmode() doesn't check this and powers down
> SERDES, what causes the link to break, and eventually results in
> the described interrupt storm.
>
> Fix this by checking whether the cmode actually changes. We want
> that the very first call to mv88e6390x_port_set_cmode() always
> configures the registers, therefore initialize port.cmode with
> a value that is different from any supported cmode value.
>
> Fixes: 364e9d7776a3 ("net: dsa: mv88e6xxx: Power on/off SERDES on cmode
> change")
> Signed-off-by: Heiner Kallweit <[email protected]>
> ---
> drivers/net/dsa/mv88e6xxx/chip.c | 4 ++++
> drivers/net/dsa/mv88e6xxx/port.c | 4 ++++
> drivers/net/dsa/mv88e6xxx/port.h | 1 +
> 3 files changed, 9 insertions(+)
>
> diff --git a/drivers/net/dsa/mv88e6xxx/chip.c
> b/drivers/net/dsa/mv88e6xxx/chip.c
> index 32e7af5ca..d4edb61e8 100644
> --- a/drivers/net/dsa/mv88e6xxx/chip.c
> +++ b/drivers/net/dsa/mv88e6xxx/chip.c
> @@ -4568,6 +4568,7 @@ static int mv88e6xxx_detect(struct mv88e6xxx_chip *chip)
> static struct mv88e6xxx_chip *mv88e6xxx_alloc_chip(struct device *dev)
> {
> struct mv88e6xxx_chip *chip;
> + int i;
>
> chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
> if (!chip)
> @@ -4578,6 +4579,9 @@ static struct mv88e6xxx_chip
> *mv88e6xxx_alloc_chip(struct device *dev)
> mutex_init(&chip->reg_lock);
> INIT_LIST_HEAD(&chip->mdios);
>
> + for (i = 0; i < ARRAY_SIZE(chip->ports); i++)
mv88e6xxx_num_ports(chip)
> + chip->ports[i].cmode = MV88E6XXX_PORT_STS_CMODE_INVALID;
> +
> return chip;
> }
>
> diff --git a/drivers/net/dsa/mv88e6xxx/port.c
> b/drivers/net/dsa/mv88e6xxx/port.c
> index ebd26b6a9..70b7a1463 100644
> --- a/drivers/net/dsa/mv88e6xxx/port.c
> +++ b/drivers/net/dsa/mv88e6xxx/port.c
> @@ -398,6 +398,10 @@ int mv88e6390x_port_set_cmode(struct mv88e6xxx_chip
> *chip, int port,
> cmode = 0;
> }
>
> + /* cmode doesn't change, nothing to do for us */
> + if (cmode == chip->ports[port].cmode)
> + return 0;
> +
> lane = mv88e6390x_serdes_get_lane(chip, port);
> if (lane < 0)
> return lane;
> diff --git a/drivers/net/dsa/mv88e6xxx/port.h
> b/drivers/net/dsa/mv88e6xxx/port.h
> index e583641de..4aadf321e 100644
> --- a/drivers/net/dsa/mv88e6xxx/port.h
> +++ b/drivers/net/dsa/mv88e6xxx/port.h
> @@ -52,6 +52,7 @@
> #define MV88E6185_PORT_STS_CMODE_1000BASE_X 0x0005
> #define MV88E6185_PORT_STS_CMODE_PHY 0x0006
> #define MV88E6185_PORT_STS_CMODE_DISABLED 0x0007
> +#define MV88E6XXX_PORT_STS_CMODE_INVALID 0xff
Is this 0xff a mask value from the Port Status register? If so please
the 0x1234 format like above, to make this mask value obvious.
>
> /* Offset 0x01: MAC (or PCS or Physical) Control Register */
> #define MV88E6XXX_PORT_MAC_CTL 0x01
Thanks,
Vivien
