[U-Boot] [PATCH 2/4] ARM: mx6: Prevent overflow in DRAM size detection

[Tim Harvey]

On Sun, Aug 3, 2014 at 4:47 PM, Marek Vasut <marex at denx.de> wrote:
> The MX6 DRAM controller can be configured to handle 4GiB of DRAM, but
> only 3840 MiB of that can be really used. In case the controller is
> configured to operate a 4GiB module, the imx_ddr_size() function will
> correctly compute that there is 4GiB of DRAM in the system. Firstly,
> the return value is 32-bit, so the function will effectively return
> zero. Secondly, the MX6 cannot address the full 4GiB, but only 3840MiB
> of all that. Thus, clamp the returned size to 3840MiB in such case.
>
> Signed-off-by: Marek Vasut <marex at denx.de>
> ---
>  arch/arm/imx-common/cpu.c | 5 +++++
>  1 file changed, 5 insertions(+)
>
> diff --git a/arch/arm/imx-common/cpu.c b/arch/arm/imx-common/cpu.c
> index 5a09107..0ec8b18 100644
> --- a/arch/arm/imx-common/cpu.c
> +++ b/arch/arm/imx-common/cpu.c
> @@ -93,6 +93,11 @@ unsigned imx_ddr_size(void)
>         bits += bank_lookup[ESD_MMDC_MISC_GET_BANK(misc)];
>         bits += ESD_MMDC_CTL_GET_WIDTH(ctl);
>         bits += ESD_MMDC_CTL_GET_CS1(ctl);
> +
> +       /* The MX6 can do only 3840 MiB of DRAM */
> +       if (bits == 32)
> +               return 0xf0000000;
> +
>         return 1 << bits;
>  }
>  #endif
> --
> 2.0.1
>

Acked-by: Tim Harvey <tharvey at gateworks.com>

Tim