netdev - Re: [PATCH 1/2 v5] fs_enet/mii-fec.c: fix MII speed calculation

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Date:	Fri, 17 Jul 2009 08:41:08 -0600
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Wolfgang Denk <wd@...x.de>
Cc:	linuxppc-dev@...abs.org, Kumar Gala <galak@...nel.crashing.org>,
	netdev@...r.kernel.org, David Miller <davem@...emloft.net>
Subject: Re: [PATCH 1/2 v5] fs_enet/mii-fec.c: fix MII speed calculation

On Fri, Jul 17, 2009 at 6:27 AM, Wolfgang Denk<wd@...x.de> wrote:
> The MII speed calculation was based on the CPU clock (ppc_proc_freq),
> but for MPC512x we must use the bus clock instead.
>
> This patch makes it use the correct clock and makes sure we don't
> clobber reserved bits in the MII_SPEED register.
>
> Signed-off-by: Wolfgang Denk <wd@...x.de>
> Cc: Grant Likely <grant.likely@...retlab.ca>
> Cc: Kumar Gala <galak@...nel.crashing.org>
> Cc: <netdev@...r.kernel.org>

Acked-by: Grant Likely <grant.likely@...retlab.ca>

David, this isn't a critical bug fix or a regression, so I think it
should be merged for -next.

g.

> ---
> v5: - fix divider so we really use 2.5 MHz (instead of 1.25)
>    - use maximum divider in case MPC512x IPS clock is unknown
>
>  drivers/net/fs_enet/mii-fec.c |   37 +++++++++++++++++++++++++++++++++----
>  1 files changed, 33 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/net/fs_enet/mii-fec.c b/drivers/net/fs_enet/mii-fec.c
> index 75a0999..5176986 100644
> --- a/drivers/net/fs_enet/mii-fec.c
> +++ b/drivers/net/fs_enet/mii-fec.c
> @@ -36,6 +36,7 @@
>  #include <asm/pgtable.h>
>  #include <asm/irq.h>
>  #include <asm/uaccess.h>
> +#include <asm/mpc5xxx.h>
>
>  #include "fs_enet.h"
>  #include "fec.h"
> @@ -103,11 +104,11 @@ static int fs_enet_fec_mii_reset(struct mii_bus *bus)
>  static int __devinit fs_enet_mdio_probe(struct of_device *ofdev,
>                                         const struct of_device_id *match)
>  {
> -       struct device_node *np = NULL;
>        struct resource res;
>        struct mii_bus *new_bus;
>        struct fec_info *fec;
> -       int ret = -ENOMEM, i;
> +       int (*get_bus_freq)(struct device_node *) = match->data;
> +       int ret = -ENOMEM, clock, speed;
>
>        new_bus = mdiobus_alloc();
>        if (!new_bus)
> @@ -133,13 +134,35 @@ static int __devinit fs_enet_mdio_probe(struct of_device *ofdev,
>        if (!fec->fecp)
>                goto out_fec;
>
> -       fec->mii_speed = ((ppc_proc_freq + 4999999) / 5000000) << 1;
> +       if (get_bus_freq) {
> +               clock = get_bus_freq(ofdev->node);
> +               if (!clock) {
> +                       /* Use maximum divider if clock is unknown */
> +                       dev_warn(&ofdev->dev, "could not determine IPS clock\n");
> +                       clock = 0x3F * 5000000;
> +               }
> +       } else
> +               clock = ppc_proc_freq;
> +
> +       /*
> +        * 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(&ofdev->dev,
> +                       "MII clock (%d Hz) exceeds max (2.5 MHz)\n",
> +                       clock / speed);
> +       }
> +
> +       fec->mii_speed = speed << 1;
>
>        setbits32(&fec->fecp->fec_r_cntrl, FEC_RCNTRL_MII_MODE);
>        setbits32(&fec->fecp->fec_ecntrl, FEC_ECNTRL_PINMUX |
>                                          FEC_ECNTRL_ETHER_EN);
>        out_be32(&fec->fecp->fec_ievent, FEC_ENET_MII);
> -       out_be32(&fec->fecp->fec_mii_speed, fec->mii_speed);
> +       clrsetbits_be32(&fec->fecp->fec_mii_speed, 0x7E, fec->mii_speed);
>
>        new_bus->phy_mask = ~0;
>        new_bus->irq = kmalloc(sizeof(int) * PHY_MAX_ADDR, GFP_KERNEL);
> @@ -188,6 +211,12 @@ static struct of_device_id fs_enet_mdio_fec_match[] = {
>        {
>                .compatible = "fsl,pq1-fec-mdio",
>        },
> +#if defined(CONFIG_PPC_MPC512x)
> +       {
> +               .compatible = "fsl,mpc5121-fec-mdio",
> +               .data = mpc5xxx_get_bus_frequency,
> +       },
> +#endif
>        {},
>  };
>
> --
> 1.6.0.6
>
>



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