README.rockchip must be removed. Move the rksd comment section to rksd.c Signed-off-by: Johan Jonker <[email protected]> Reviewed-by: Simon Glass <[email protected]> --- tools/rksd.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/tools/rksd.c b/tools/rksd.c index 7d46a1b07b3a..ea12b9cac12e 100644 --- a/tools/rksd.c +++ b/tools/rksd.c @@ -3,7 +3,26 @@ * (C) Copyright 2015 Google, Inc * Written by Simon Glass <[email protected]> * - * See README.rockchip for details of the rksd format + * rksd.c produces an image consisting of 32KB of empty space, a header and + * u-boot-spl-dtb.bin. The header is defined by 'struct header0_info' although + * most of the fields are unused by U-Boot. We just need to specify the + * signature, a flag and the block offset and size of the SPL image. + * + * The header occupies a single block but we pad it out to 4 blocks. The header + * is encoding using RC4 with the key 7c4e0304550509072d2c7b38170d1711. The SPL + * image can be encoded too but we don't do that. + * + * The maximum size of u-boot-spl-dtb.bin which the boot ROM will read is 32KB, + * or 0x40 blocks. This is a severe and annoying limitation. There may be a way + * around this limitation, since there is plenty of SRAM, but at present the + * board refuses to boot if this limit is exceeded. + * + * The image produced is padded up to a block boundary (512 bytes). It should be + * written to the start of an SD card using dd. + * + * Since this image is set to load U-Boot from the SD card at block offset, + * CONFIG_SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR, dd should be used to write + * u-boot-dtb.img to the SD card at that offset. */ #include "imagetool.h" -- 2.39.5
