On 19/04/16 17:26, Roger Quadros wrote: > On 19/04/16 16:22, Boris Brezillon wrote: >> On Mon, 18 Apr 2016 17:39:01 +0300 >> Roger Quadros <rogerq@xxxxxx> wrote: >> >>> On 18/04/16 17:10, Boris Brezillon wrote: >>>> On Mon, 18 Apr 2016 16:48:26 +0300 >>>> Roger Quadros <rogerq@xxxxxx> wrote: >>>> >>>>> Boris, >>>>> >>>>> On 18/04/16 16:13, Boris Brezillon wrote: >>>>>> Hi Roger, >>>>>> >>>>>> On Mon, 18 Apr 2016 15:52:58 +0300 >>>>>> Roger Quadros <rogerq@xxxxxx> wrote: >>>>>> >>>>>>> On 18/04/16 15:31, Roger Quadros wrote: >>>>>>>> On 16/04/16 11:57, Boris Brezillon wrote: >>>>>>>>> On Fri, 15 Apr 2016 09:19:51 -0700 >>>>>>>>> Tony Lindgren <tony@xxxxxxxxxxx> wrote: >>>>>>>>> >>>>>>>>>> >>>>>>>>>>> Or should I just pull this immutable branch in my current nand/next and >>>>>>>>>>> let you pull the same immutable branch in omap-soc. I mean, would this >>>>>>>>>>> prevent conflicts when our branches are merged into linux-next, no >>>>>>>>>>> matter the order. >>>>>>>>>> >>>>>>>>>> Ideally just one or more branches with just minimal changes in >>>>>>>>>> them against -rc1. But you may have other dependencies in >>>>>>>>>> your NAND tree so that may no longer be doable :) Usually if >>>>>>>>>> I merge something that may need to get merged into other >>>>>>>>>> branches, I just apply them into a separate branch against -rc1 >>>>>>>>>> to start with, then merge that branch in. >>>>>>>>> >>>>>>>>> Okay, in this case, that's pretty much what I did from the beginning, >>>>>>>>> except the immutable branch was provided by Roger (based on 4.6-rc1). >>>>>>>>> Thanks for this detailed explanation, I'll try to remember that when >>>>>>>>> I'll need to provide an immutable branch for another subsystem. >>>>>>>>> >>>>>>>>> Roger, my request remains, could you check/test my conflict resolution >>>>>>>>> (branch nand/next-with-gpmc-rework)? >>>>>>>> >>>>>>>> I couldn't test that branch yet as nand/next is broken on omap platforms >>>>>>>> (at least on dra7-evm). >>>>>>>> >>>>>>>> The commit where it breaks is: >>>>>>>> a662ef4 mtd: nand: omap2: use mtd_ooblayout_xxx() helpers where appropriate >>>>>>>> >>>>>>>> I'm trying to figure out what went wrong there. Failure log below. >>>>>>> >>>>>>> OK. I was able to fix it when at commit a662ef4 with the below patch. >>>>>> >>>>>> Thanks for debugging that. >>>>>> >>>>>>> >>>>>>> Looks like we need to read exactly the ECC bytes through the ECC engine and not >>>>>>> the entire OOB region. >>>>>> >>>>>> Hm, it looks like there's a bug somewhere else, because I don't see any >>>>>> reason why the controller wouldn't be able to read the full OOB region. >>>>> >>>>> The controller can read the full OOB region but we only want it to read just >>>>> the ECC bytes because that is the way the ELM ECC engine works. >>>> >>>> Ok, I think I got it: the ECC correction is pipelined with data read, >>>> and the controller expect to have ECC bytes right after the in-band >>>> data, is that correct? >>> >>> That is correct. >>> >>>> >>>>> >>>>>>> >>>>>>> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c >>>>>>> index e622a1b..46b61d2 100644 >>>>>>> --- a/drivers/mtd/nand/omap2.c >>>>>>> +++ b/drivers/mtd/nand/omap2.c >>>>>>> @@ -1547,8 +1547,8 @@ static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip, >>>>>>> chip->read_buf(mtd, buf, mtd->writesize); >>>>>>> >>>>>>> /* Read oob bytes */ >>>>>>> - chip->cmdfunc(mtd, NAND_CMD_RNDOUT, mtd->writesize, -1); >>>>>>> - chip->read_buf(mtd, chip->oob_poi, mtd->oobsize); >>>>>>> + chip->cmdfunc(mtd, NAND_CMD_RNDOUT, mtd->writesize + chip->ecc.layout->eccpos[0], -1); >>>>>> >>>>>> The whole point of this series is to get rid of chip->ecc.layout, so >>>>>> we'd rather use the mtd_ooblayout_find_eccregion() instead of >>>>>> chip->ecc.layout->eccpos[0]. >>>>> >>>>> We just need the position of the first ECC byte offset. >>>>> Is that the most optimal way to get it? >>>> >>>> For the BCH case, it seems that ECC bytes always start at offset >>>> BADBLOCK_MARKER_LENGTH, so you can just pass >>>> mtd->writesize + BADBLOCK_MARKER_LENGTH. >>>> >>>> Let me know if this works, and I'll squash those changes into the >>>> faulty commit (I know this implies a rebase + push -f, but IMO that's >>>> better than breaking bisectability). >>>> >>>> >>> >>> So, the below patch works as well. Please feel free to fold it with your patch. >>> >>> -- >>> cheers, >>> -roger >>> >>> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c >>> index e622a1b..eb85d6b 100644 >>> --- a/drivers/mtd/nand/omap2.c >>> +++ b/drivers/mtd/nand/omap2.c >>> @@ -1547,8 +1547,8 @@ static int omap_read_page_bch(struct mtd_info *mtd, struct nand_chip *chip, >>> chip->read_buf(mtd, buf, mtd->writesize); >>> >>> /* Read oob bytes */ >>> - chip->cmdfunc(mtd, NAND_CMD_RNDOUT, mtd->writesize, -1); >>> - chip->read_buf(mtd, chip->oob_poi, mtd->oobsize); >>> + chip->cmdfunc(mtd, NAND_CMD_RNDOUT, mtd->writesize + BADBLOCK_MARKER_LENGTH, -1); >>> + chip->read_buf(mtd, chip->oob_poi, chip->ecc.total); >> >> Are you sure this patch works? Cause it seems to me that it should be > > For my limited test case yes. My test case involves reading an existing ubifs partition > and creating a new one and then reading it back using an older kernel. > >> >> chip->read_buf(mtd, chip->oob_poi + BADBLOCK_MARKER_LENGTH, >> chip->ecc.total); >> > > You are right. Else we'd have wrong OOB data during reads. Strange, but nanddump is showing the correct OOB data with or without this change. I'm puzzled. -- cheers, -roger -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
