Align the DFU MTD backend for the UBI partitions with the mtd command write behavior when the option .dontskipff is not used: don't write the empty pages (full of 0xFF); it is not required for UBI, see [1] for details.
This patch avoids the "free space fixup" procedure in the kernel [2] and allows to program a UBIFS volume generated by mkfs.ubifs without the option -F, --space-fixup. The MTD DFU backend implements this behavior introduced on DFU NAND backend by the commit 13cb7cc9e8e4 ("dfu: Add option to skip empty pages when flashing UBI images to NAND") and also supported by the command nand by CONFIG_CMD_NAND_TRIMFFS and by commit c9494866df83 ("cmd_nand: add nand write.trimffs command"). [1] http://www.linux-mtd.infradead.org/doc/ubi.html#L_flasher_algo [2] http://www.linux-mtd.infradead.org/faq/ubifs.html#L_free_space_fixup Signed-off-by: Patrick Delaunay <patrick.delau...@foss.st.com> --- drivers/dfu/dfu_mtd.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) diff --git a/drivers/dfu/dfu_mtd.c b/drivers/dfu/dfu_mtd.c index 0b7f17761f..cce9ce0845 100644 --- a/drivers/dfu/dfu_mtd.c +++ b/drivers/dfu/dfu_mtd.c @@ -18,6 +18,20 @@ static bool mtd_is_aligned_with_block_size(struct mtd_info *mtd, u64 size) return !do_div(size, mtd->erasesize); } +/* Logic taken from cmd/mtd.c:mtd_oob_write_is_empty() */ +static bool mtd_page_is_empty(struct mtd_oob_ops *op) +{ + int i; + + for (i = 0; i < op->len; i++) + if (op->datbuf[i] != 0xff) + return false; + + /* oob is not used, with MTD_OPS_AUTO_OOB & ooblen=0 */ + + return true; +} + static int mtd_block_op(enum dfu_op op, struct dfu_entity *dfu, u64 offset, void *buf, long *len) { @@ -129,8 +143,14 @@ static int mtd_block_op(enum dfu_op op, struct dfu_entity *dfu, if (op == DFU_OP_READ) ret = mtd_read_oob(mtd, off, &io_op); - else + else if (has_pages && dfu->data.mtd.ubi && mtd_page_is_empty(&io_op)) { + /* in case of ubi partition, do not write an empty page, only skip it */ + ret = 0; + io_op.retlen = mtd->writesize; + io_op.oobretlen = mtd->oobsize; + } else { ret = mtd_write_oob(mtd, off, &io_op); + } if (ret) { printf("Failure while %s at offset 0x%llx\n", -- 2.25.1