Messages in this thread | | | Date | Mon, 30 Nov 2020 18:50:42 +0530 | From | Pratyush Yadav <> | Subject | Re: [PATCH v2 1/3] UBI: Do not zero out EC and VID on ECC-ed NOR flashes |
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On 28/11/20 10:58AM, Tudor.Ambarus@microchip.com wrote: > On 11/18/20 8:24 PM, Pratyush Yadav wrote: > > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe > > > > For NOR flashes EC and VID are zeroed out before an erase is issued to > > make sure UBI does not mistakenly treat the PEB as used and associate it > > with an LEB. > > > > But on some flashes, like the Cypress Semper S28 SPI NOR flash family, > > multi-pass page programming is not allowed on the default ECC scheme. > > This means zeroing out these magic numbers will result in the flash > > throwing a page programming error. > > > > Do not zero out EC and VID for such flashes. A writesize > 1 is an > > indication of an ECC-ed flash. > > > > Signed-off-by: Pratyush Yadav <p.yadav@ti.com> > > --- > > > > Notes: > > Changes in v2: > > > > - Use mtd->writesize to check if multi-pass programming can be done > > instead of using MTD_NO_MULTI_PASS_WRITE. > > - Remove the assertion that a NOR flash most have writesize of 1. > > > > drivers/mtd/ubi/build.c | 4 +--- > > drivers/mtd/ubi/io.c | 9 ++++++++- > > 2 files changed, 9 insertions(+), 4 deletions(-) > > > > diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c > > index e85b04e9716b..25fd7816b1f4 100644 > > --- a/drivers/mtd/ubi/build.c > > +++ b/drivers/mtd/ubi/build.c > > @@ -628,10 +628,8 @@ static int io_init(struct ubi_device *ubi, int max_beb_per1024) > > ubi->bad_peb_limit = get_bad_peb_limit(ubi, max_beb_per1024); > > } > > > > - if (ubi->mtd->type == MTD_NORFLASH) { > > - ubi_assert(ubi->mtd->writesize == 1); > > + if (ubi->mtd->type == MTD_NORFLASH) > > ubi->nor_flash = 1; > > - } > > > > ubi->min_io_size = ubi->mtd->writesize; > > ubi->hdrs_min_io_size = ubi->mtd->writesize >> ubi->mtd->subpage_sft; > > diff --git a/drivers/mtd/ubi/io.c b/drivers/mtd/ubi/io.c > > index 14d890b00d2c..2f3312c31e51 100644 > > --- a/drivers/mtd/ubi/io.c > > +++ b/drivers/mtd/ubi/io.c > > @@ -535,7 +535,14 @@ int ubi_io_sync_erase(struct ubi_device *ubi, int pnum, int torture) > > return -EROFS; > > } > > > > - if (ubi->nor_flash) { > > + /* > > + * If the flash is ECC-ed then we have to erase the ECC block before we > > + * can write to it. But the write is in preparation to an erase in the > > + * first place. This means we cannot zero out EC and VID before the > > + * erase and we just have to hope the flash starts erasing from the > > + * start of the page. > > + */ > > + if (ubi->nor_flash && ubi->mtd->writesize == 1) { > > Are there any SPI NORs with ECC block size of 4 bytes? Should we call > nor_erase_prepare() in this case?
None that I know of. But even if there was such a flash this check would continue to be correct.
Like Vignesh explained in the previous version, mtd->writesize > 1 means that multi-pass writes are not allowed in that ECC block. So even if a flash has ECC block size of 4, we still are not allowed to write 4 (or less) bytes to it before erasing first. > Anyway, there's none in SPI NOR as of now, so: > > Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com> > > > err = nor_erase_prepare(ubi, pnum); > > if (err) > > return err; > > -- > > 2.28.0 > > >
-- Regards, Pratyush Yadav Texas Instruments India
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