rockchip: Drop first 32kb of zeros from the rkSD image type

Instead of creating a rockchip SPL SD card image with 32KB of zeros
which can be written to the start of an SD card, create the images with
only the useful data that should be written to an offset of 32KB on the
SD card.

The first 32 kilobytes aren't needed for bootup and only serve as
convenient way of accidentally obliterating your partition table.

Signed-off-by: Sjoerd Simons <sjoerd.simons@collabora.co.uk>
Acked-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/doc/README.rockchip b/doc/README.rockchip
index ce8ce77..347fc05 100644
--- a/doc/README.rockchip
+++ b/doc/README.rockchip
@@ -90,7 +90,7 @@
 To write an image that boots from an SD card (assumed to be /dev/sdc):
 
    ./firefly-rk3288/tools/mkimage -T rksd -d firefly-rk3288/spl/u-boot-spl-dtb.bin out
-   sudo dd if=out of=/dev/sdc
+   sudo dd if=out of=/dev/sdc seek=64
    sudo dd if=firefly-rk3288/u-boot-dtb.img of=/dev/sdc seek=256
 
 This puts the Rockchip header and SPL image first and then places the U-Boot
diff --git a/tools/rksd.c b/tools/rksd.c
index 2efcd68..a8dbe98 100644
--- a/tools/rksd.c
+++ b/tools/rksd.c
@@ -14,9 +14,7 @@
 #include "rkcommon.h"
 
 enum {
-	RKSD_HEADER0_START	= 64 * RK_BLK_SIZE,
-	RKSD_SPL_HDR_START	= RKSD_HEADER0_START +
-					RK_CODE1_OFFSET * RK_BLK_SIZE,
+	RKSD_SPL_HDR_START	= RK_CODE1_OFFSET * RK_BLK_SIZE,
 	RKSD_SPL_START		= RKSD_SPL_HDR_START + 4,
 	RKSD_HEADER_LEN		= RKSD_SPL_START,
 };
@@ -44,11 +42,8 @@
 	unsigned int size;
 	int ret;
 
-	/* Zero the whole header. The first 32KB is empty */
-	memset(buf,  '\0',  RKSD_HEADER0_START);
-
 	size = params->file_size - RKSD_SPL_HDR_START;
-	ret = rkcommon_set_header(buf + RKSD_HEADER0_START, size);
+	ret = rkcommon_set_header(buf, size);
 	if (ret) {
 		/* TODO(sjg@chromium.org): This method should return an error */
 		printf("Warning: SPL image is too large (size %#x) and will not boot\n",