[U-Boot] [PATCH 3/3] rockchip: rk3188: add README.rockchip paragraph describing sd boot

[Kever Yang <kever.yang@rock-chips.com>]

Hi Heiko,

On 03/24/2017 07:41 AM, Heiko Stuebner wrote:
> Building sd images for rk3188 requires more steps due to the needed split
> into TPL and SPL as loaders. Describe how to build an image for it in a
> separate paragraph in the READER.rockchip file.
>
> Signed-off-by: Heiko Stuebner <heiko@sntech.de>
> ---
>   doc/README.rockchip | 26 ++++++++++++++++++++++++++
>   1 file changed, 26 insertions(+)
>
> diff --git a/doc/README.rockchip b/doc/README.rockchip
> index 186a1a007e..cb81efd4bf 100644
> --- a/doc/README.rockchip
> +++ b/doc/README.rockchip
> @@ -147,6 +147,32 @@ For evb_rk3036 board:
>   Note: rk3036 SDMMC and debug uart use the same iomux, so if you boot from SD, the
>         debug uart must be disabled
>   
> +
> +Booting from an SD card on RK3188
> +=================================
> +
> +For rk3188 boards the general storage onto the card stays the same as
> +described above, but the image creation needs a bit more care.
> +
> +The bootrom of rk3188 expects to find a small 1kb loader which returns
> +control to the bootrom, after which it will load the real loader, which
> +can then be up to 29kb in size and does the regular ddr init.
> +
> +Additionally the rk3188 requires everything the bootrom loads to be
> +rc4-encrypted. Except for the very first stage the bootrom always reads
> +and decodes 2kb pages, so files should be sized accordingly.
> +
> +# copy tpl, pad to 1020 bytes and append spl
> +cat tpl/u-boot-tpl.bin > tplspl.bin
> +truncate -s 1020 tplspl.bin
> +cat spl/u-boot-spl.bin >> tplspl.bin
> +tools/mkimage -n rk3188 -T rksd -d tplspl.bin out
> +
> +# truncate, encode and append u-boot.bin
> +truncate -s %2048 u-boot.bin
> +cat u-boot.bin | split -b 512 --filter='openssl rc4 -K 7C4E0304550509072D2C7B38170D1711' >> out
> +
> +
>   Using fastboot on rk3288
>   ========================
>   - Write GPT partition layout to mmc device which fastboot want to use it to

Reviewed-by: Kever Yang <kever.yang@rock-chips.com>

Thanks,
- Kever