[PATCH v1 1/2] fastboot: mmc: make boot partition offset configurable

Heiko Schocher
2026-01-24T05:47:29Z

From: Adrian Freihofer <adrian.freihofer@siemens.com>

Add a weak function fb_mmc_get_boot_offset() to allow to override
the default offset (0) when writing to eMMC boot partitions.
This enables support for devices with non-standard boot partition
layouts, such as those requiring an offset for correct bootloader
placement.

The imx8qxp processors are an example where older revisions need a
32kB offset.

Signed-off-by: Adrian Freihofer <adrian.freihofer@siemens.com>
Signed-off-by: Heiko Schocher <hs@nabladev.com>
---

drivers/fastboot/fb_block.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/fastboot/fb_block.c b/drivers/fastboot/fb_block.c
index 2a7e47992f8..51d1abb18c7 100644
--- a/drivers/fastboot/fb_block.c
+++ b/drivers/fastboot/fb_block.c
@@ -28,6 +28,11 @@
*/
#define FASTBOOT_MAX_BLOCKS_WRITE 65536

+__weak lbaint_t fb_mmc_get_boot_offset(void)
+{
+ return 0;
+}
+
struct fb_block_sparse {
struct blk_desc *dev_desc;
};
@@ -160,7 +165,8 @@ void fastboot_block_raw_erase_disk(struct blk_desc *dev_desc, const char *disk_n

debug("Start Erasing %s...\n", disk_name);

- written = fb_block_write(dev_desc, 0, dev_desc->lba, NULL);
+ written = fb_block_write(dev_desc, fb_mmc_get_boot_offset(),
+ dev_desc->lba, NULL);
if (written != dev_desc->lba) {
pr_err("Failed to erase %s\n", disk_name);
fastboot_response("FAIL", response, "Failed to erase %s", disk_name);
@@ -211,7 +217,8 @@ void fastboot_block_erase(const char *part_name, char *response)
if (fastboot_block_get_part_info(part_name, &dev_desc, &part_info, response) < 0)
return;

- fastboot_block_raw_erase(dev_desc, &part_info, part_name, 0, response);
+ fastboot_block_raw_erase(dev_desc, &part_info, part_name,
+ fb_mmc_get_boot_offset(), response);
}

void fastboot_block_write_raw_disk(struct blk_desc *dev_desc, const char *disk_name,
@@ -224,7 +231,7 @@ void fastboot_block_write_raw_disk(struct blk_desc *dev_desc, const char *disk_n
blkcnt = ((download_bytes + (dev_desc->blksz - 1)) & ~(dev_desc->blksz - 1));
blkcnt = lldiv(blkcnt, dev_desc->blksz);

- if (blkcnt > dev_desc->lba) {
+ if ((blkcnt + fb_mmc_get_boot_offset()) > dev_desc->lba) {
pr_err("too large for disk: '%s'\n", disk_name);
fastboot_fail("too large for disk", response);
return;
@@ -232,7 +239,7 @@ void fastboot_block_write_raw_disk(struct blk_desc *dev_desc, const char *disk_n

printf("Flashing Raw Image\n");

- blks = fb_block_write(dev_desc, 0, blkcnt, buffer);
+ blks = fb_block_write(dev_desc, fb_mmc_get_boot_offset(), blkcnt, buffer);

if (blks != blkcnt) {
pr_err("failed writing to %s\n", disk_name);
--
2.20.1