netdev - Re: [PATCH 2/4] mpc8569mds: Add bscr setting for rtbi mode

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Date:	Mon, 1 Feb 2010 14:57:31 -0700
From:	Grant Likely <grant.likely@...retlab.ca>
To:	Liu Yu <yu.liu@...escale.com>
Cc:	galak@...nel.crashing.org, davem@...emloft.net,
	netdev@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH 2/4] mpc8569mds: Add bscr setting for rtbi mode

On Thu, Jan 14, 2010 at 1:13 AM, Liu Yu <yu.liu@...escale.com> wrote:
> Signed-off-by: Liu Yu <yu.liu@...escale.com>
> ---
>  arch/powerpc/platforms/85xx/mpc85xx_mds.c |   24 ++++++++++++++++++++++++
>  1 files changed, 24 insertions(+), 0 deletions(-)
>
> diff --git a/arch/powerpc/platforms/85xx/mpc85xx_mds.c b/arch/powerpc/platforms/85xx/mpc85xx_mds.c
> index c5028a2..0872e4a 100644
> --- a/arch/powerpc/platforms/85xx/mpc85xx_mds.c
> +++ b/arch/powerpc/platforms/85xx/mpc85xx_mds.c
> @@ -237,6 +237,8 @@ static void __init mpc85xx_mds_setup_arch(void)
>                } else if (machine_is(mpc8569_mds)) {
>  #define BCSR7_UCC12_GETHnRST   (0x1 << 2)
>  #define BCSR8_UEM_MARVELL_RST  (0x1 << 1)
> +#define BCSR_UCC_RGMII         (0x1 << 6)
> +#define BCSR_UCC_RTBI          (0x1 << 5)
>                        /*
>                         * U-Boot mangles interrupt polarity for Marvell PHYs,
>                         * so reset built-in and UEM Marvell PHYs, this puts
> @@ -247,6 +249,28 @@ static void __init mpc85xx_mds_setup_arch(void)
>
>                        setbits8(&bcsr_regs[7], BCSR7_UCC12_GETHnRST);
>                        clrbits8(&bcsr_regs[8], BCSR8_UEM_MARVELL_RST);
> +
> +                       for (np = NULL; (np = of_find_compatible_node(np,
> +                                                       "network",

Don't match on the 'type' field.  Replace "network" with NULL and just
rely on "ucc_geth" for matching.

> +                                                       "ucc_geth")) != NULL;) {
> +                               const unsigned int *prop;

u32 please.

Also, rather than reusing 'prop' for both char* and u32 values, which
forces you to use ugly casts, use 2 local variables here.

> +                               int ucc_num;
> +
> +                               prop = of_get_property(np, "cell-index", NULL);
> +                               if (prop == NULL)
> +                                       continue;
> +
> +                               ucc_num = *prop - 1;

Ugh.  No bounds checking...

> +
> +                               prop = of_get_property(np, "phy-connection-type", NULL);
> +                               if (prop == NULL)
> +                                       continue;
> +
> +                               if (strcmp("rtbi", (const char *)prop) == 0)

(This is the ugly cast I was talking about.)

> +                                       clrsetbits_8(&bcsr_regs[7 + ucc_num],

...not having bounds checking could result in badness in this array index.

This patch is dangerous as written.

Finally, while using cell-index seems convenient, I think it would be
better to have a lookup table of the index into the BCSR register
block from the UCC base address, which also gives you implicit bounds
checking.

g.

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