Hi Boris,
2017-02-28 17:02 GMT+09:00 Boris Brezillon <[email protected]>: > On Tue, 28 Feb 2017 16:21:50 +0900 > Masahiro Yamada <[email protected]> wrote: > >> Hi. >> >> >> I am seeing the reference implementations for the callback >> in drivers/mtd/nand/nand_base.c >> >> >> I see only some of them use the argument "oob_required". >> >> >> - oob_required is used >> nand_read_page_raw() >> nand_write_page_raw() >> nand_write_subpage_hwecc() >> >> >> - oob_required is ignored >> nand_read_page_raw_syndrome() >> nand_read_page_swecc() >> nand_read_page_hwecc() >> nand_read_page_hwecc_oob_first() >> nand_read_page_syndrome() >> nand_write_page_raw_syndrome() >> nand_write_page_swecc() >> nand_write_page_hwecc() >> nand_write_page_syndrome() >> >> >> >> I could not get the logic >> when "oob_required" is used. >> >> >> >> When implementing drivers, the "oob_required" >> should be respected (i.e. oob_poi should be transferred as well), >> or is it OK to ignore it? >> >> > > oob_required = true => you must retrieve OOB bytes > oob_required = false => you can optimize the process and ignore OOB > bytes, but you can also retrieve them if you don't care about > optimization. That's usually what's done when you have to retrieve ECC > bytes (retrieving a few extra OOB bytes is not expensive and usually > simplifies the logic, especially when free and ECC bytes are > interleaved in the OOB region). Ah, I see. The functions that ignore "oob_required" always transfer the oob_poi. Thanks! -- Best Regards Masahiro Yamada
