On 08/22/2012 03:34 PM, Joe Hershberger wrote: > Hi Scott, > > On Fri, Aug 17, 2012 at 3:53 PM, Scott Wood <scottw...@freescale.com> wrote: >> On 08/17/2012 03:31 PM, Joe Hershberger wrote: >>> NAND unlock command allows an invert bit to be set to unlock all but >>> the selected page range. >>> >>> Signed-off-by: Joe Hershberger <joe.hershber...@ni.com> >>> --- >>> common/cmd_nand.c | 13 ++++++++++--- >>> drivers/mtd/nand/nand_util.c | 9 ++++++--- >>> include/nand.h | 4 ++-- >>> 3 files changed, 18 insertions(+), 8 deletions(-) >>> >>> @@ -368,6 +369,8 @@ int nand_unlock(struct mtd_info *mtd, ulong start, >>> ulong length) >>> >>> /* submit ADDRESS of LAST page to unlock */ >>> page += (int)(length >> chip->page_shift); >>> + if (invert) >>> + page |= 1; >>> chip->cmdfunc(mtd, NAND_CMD_UNLOCK2, -1, page & chip->pagemask); >> >> Why |= 1? Is this some magic that the chip recognizes to implement >> "invert"? Do all chips that support lock/unlock support this (none of >> the NAND chip manuals I have document lock/unlock at all as far as I >> could find)? What if you want to unlock a non-inverted range that ends >> in a page with the low bit set? > > According to the data sheet for the part I'm working with > (MT29F4G08ABADAH4) the unlock command has 2 commands... 0x23 and 0x24. > The invert bit only exists for 0x24 (NAND_CMD_UNLOCK2). The format > of the unlock commands specifys that block addresses are used, > therefore the LSb would never be set. This bit-0 is defined to be > "invert area" for 0x24 and always LOW for 0x23.
Please add a code comment to this effect. -Scott _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
