[PATCH 2/2 v4] MPC52xx FEC: be more conservative when setting MII_SPEED register

[Grant Likely]

On Fri, Jul 17, 2009 at 6:59 AM, Wolfgang Denk<wd at denx.de> wrote:
> This patch adds error checking and prevents clobbering unrelated bits
> (reserved bits or the DIS_PREAMBLE bit) when writing the MII_SPEED
> register on MPC52xx systems.
>
> Signed-off-by: Wolfgang Denk <wd at denx.de>
> Cc: Grant Likely <grant.likely at secretlab.ca>
> Cc: Kumar Gala <galak at kernel.crashing.org>
> Cc: <netdev at vger.kernel.org>
> ---
> v3: - use maximum divider in case MPC512x IPS clock is unknown
> v4: - use the same code in the probe-function, too
>
>  drivers/net/fec_mpc52xx.c     |   25 ++++++++++++++++++++++---
>  drivers/net/fec_mpc52xx_phy.c |   23 ++++++++++++++++++++---

Blech.  now this block of duplicated code I don't like.  This is all
one device, so surely the mdio speed can be calculated once and used
for both drivers.... let me think about this for a bit.  'course this
problem is all rolled up in the nastiness of having two drivers
working on the same device.  I suspect is was a mistake to split up
all the powerpc ethernet drivers into separate of_platform drivers.

g.

>  2 files changed, 42 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/net/fec_mpc52xx.c b/drivers/net/fec_mpc52xx.c
> index cc78633..eed8d2b 100644
> --- a/drivers/net/fec_mpc52xx.c
> +++ b/drivers/net/fec_mpc52xx.c
> @@ -639,7 +639,7 @@ static void mpc52xx_fec_hw_init(struct net_device *dev)
>        /* set phy speed.
>         * this can't be done in phy driver, since it needs to be called
>         * before fec stuff (even on resume) */
> -       out_be32(&fec->mii_speed, priv->mdio_speed);
> +       clrsetbits_be32(&fec->mii_speed, 0x7E, priv->mdio_speed);
>  }
>
>  /**
> @@ -863,7 +863,7 @@ mpc52xx_fec_probe(struct of_device *op, const struct of_device_id *match)
>        struct mpc52xx_fec_priv *priv = NULL;
>        struct resource mem;
>        const u32 *prop;
> -       int prop_size;
> +       int prop_size, clock, speed;
>
>        phys_addr_t rx_fifo;
>        phys_addr_t tx_fifo;
> @@ -948,7 +948,26 @@ mpc52xx_fec_probe(struct of_device *op, const struct of_device_id *match)
>        /* Start with safe defaults for link connection */
>        priv->speed = 100;
>        priv->duplex = DUPLEX_HALF;
> -       priv->mdio_speed = ((mpc5xxx_get_bus_frequency(op->node) >> 20) / 5) << 1;
> +
> +       /* MII speed */
> +       clock = mpc5xxx_get_bus_frequency(op->node);
> +       if (!clock) {
> +               /* Use maximum divider if clock is unknown */
> +               dev_err(&op->dev, "could not determine IPB clock\n");
> +               clock = 0x3F * 5000000;
> +       }
> +
> +       /*
> +        * Scale for a MII clock <= 2.5 MHz
> +        * Note that only 6 bits (25:30) are available for MII speed.
> +        */
> +       speed = (clock + 4999999) / 5000000;
> +       if (speed > 0x3F) {
> +               speed = 0x3F;
> +               dev_err(&op->dev, "MII clock (%d Hz) exceeds max (2.5 MHz)\n",
> +                       clock / speed);
> +       }
> +       priv->mdio_speed = speed << 1;
>
>        /* The current speed preconfigures the speed of the MII link */
>        prop = of_get_property(op->node, "current-speed", &prop_size);
> diff --git a/drivers/net/fec_mpc52xx_phy.c b/drivers/net/fec_mpc52xx_phy.c
> index 31e6d62..d3537e1 100644
> --- a/drivers/net/fec_mpc52xx_phy.c
> +++ b/drivers/net/fec_mpc52xx_phy.c
> @@ -70,7 +70,7 @@ static int mpc52xx_fec_mdio_probe(struct of_device *of,
>        struct mpc52xx_fec_mdio_priv *priv;
>        struct resource res = {};
>        int err;
> -       int i;
> +       int i, clock, speed;
>
>        bus = mdiobus_alloc();
>        if (bus == NULL)
> @@ -105,8 +105,25 @@ static int mpc52xx_fec_mdio_probe(struct of_device *of,
>        dev_set_drvdata(dev, bus);
>
>        /* set MII speed */
> -       out_be32(&priv->regs->mii_speed,
> -               ((mpc5xxx_get_bus_frequency(of->node) >> 20) / 5) << 1);
> +       clock = mpc5xxx_get_bus_frequency(of->node);
> +       if (!clock) {
> +               /* Use maximum divider if clock is unknown */
> +               dev_err(&of->dev, "could not determine IPB clock\n");
> +               clock = 0x3F * 5000000;
> +       }
> +
> +       /*
> +        * Scale for a MII clock <= 2.5 MHz
> +        * Note that only 6 bits (25:30) are available for MII speed.
> +        */
> +       speed = (clock + 4999999) / 5000000;
> +       if (speed > 0x3F) {
> +               speed = 0x3F;
> +               dev_err(&of->dev, "MII clock (%d Hz) exceeds max (2.5 MHz)\n",
> +                       clock / speed);
> +       }
> +
> +       clrsetbits_be32(&priv->regs->mii_speed, 0x7E, speed << 1);
>
>        err = of_mdiobus_register(bus, np);
>        if (err)
> --
> 1.6.0.6
>
>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.