[v3,1/3] riscv: Avoid the reserved memory fixup if src and dst point to the same place

From: Bin Meng <bin.meng at windriver.com>

The copy of reserved memory node from source dtb to destination dtb
can be avoided if they point to the same place. This is useful when
OF_PRIOR_STAGE is used.

Signed-off-by: Bin Meng <bin.meng at windriver.com>
Reviewed-by: Rick Chen <rick at andestech.com>
---

(no changes since v1)

 arch/riscv/lib/fdt_fixup.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

On Thu, Jun 25, 2020 at 12:38 AM Bin Meng <bmeng.cn at gmail.com> wrote:
>
> From: Bin Meng <bin.meng at windriver.com>
>
> The copy of reserved memory node from source dtb to destination dtb
> can be avoided if they point to the same place. This is useful when
> OF_PRIOR_STAGE is used.
>
> Signed-off-by: Bin Meng <bin.meng at windriver.com>
> Reviewed-by: Rick Chen <rick at andestech.com>
> ---
>
> (no changes since v1)
>
>  arch/riscv/lib/fdt_fixup.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/lib/fdt_fixup.c b/arch/riscv/lib/fdt_fixup.c
> index 6db48ad..5f523f0 100644
> --- a/arch/riscv/lib/fdt_fixup.c
> +++ b/arch/riscv/lib/fdt_fixup.c
> @@ -82,10 +82,9 @@ int riscv_fdt_copy_resv_mem_node(const void *src, void *dst)
>   * @fdt: Pointer to the device tree in which reserved memory node needs to be
>   *      added.
>   *
> - * In RISC-V, any board compiled with OF_SEPARATE needs to copy the reserved
> - * memory node from the device tree provided by the firmware to the device tree
> - * used by U-Boot. This is a common function that individual board fixup
> - * functions can invoke.
> + * In RISC-V, any board needs to copy the reserved memory node from the device
> + * tree provided by the firmware to the device tree used by U-Boot. This is a
> + * common function that individual board fixup functions can invoke.
>   *
>   * Return: 0 on success or error otherwise.
>   */
> @@ -95,6 +94,11 @@ int riscv_board_reserved_mem_fixup(void *fdt)
>         void *src_fdt_addr;
>
>         src_fdt_addr = map_sysmem(gd->arch.firmware_fdt_addr, 0);
> +
> +       /* avoid the copy if we are using the same device tree */
> +       if (src_fdt_addr == fdt)
> +               return 0;
> +
>         err = riscv_fdt_copy_resv_mem_node(src_fdt_addr, fdt);
>         if (err < 0)
>                 return err;
> --
> 2.7.4
>

Reviewed-by: Atish Patra <atish.patra at wdc.com>