[v3,1/3] UBI: Do not zero out EC and VID on ECC-ed NOR flashes
diff mbox series

Message ID 20201201102711.8727-2-p.yadav@ti.com
State New, archived
Headers show
Series
  • mtd: Make sure UBIFS does not do multi-pass page programming on flashes that don't support it
Related show

Commit Message

Pratyush Yadav Dec. 1, 2020, 10:27 a.m. UTC
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>
Reviewed-by: Tudor Ambarus <tudor.ambarus@microchip.com>
---

Notes:
    No changes in v3.
    
    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(-)

Comments

Pratyush Yadav Dec. 8, 2020, 6:10 p.m. UTC | #1
Richard,

On 01/12/20 03:57PM, Pratyush Yadav wrote:
> 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.

Patches 2/3 and 3/3 have been picked up in the spi-nor tree. Can you 
please pick this patch up?
Richard Weinberger Dec. 13, 2020, 11:25 p.m. UTC | #2
On Tue, Dec 8, 2020 at 7:17 PM Pratyush Yadav <p.yadav@ti.com> wrote:
>
> Richard,
>
> On 01/12/20 03:57PM, Pratyush Yadav wrote:
> > 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.
>
> Patches 2/3 and 3/3 have been picked up in the spi-nor tree. Can you
> please pick this patch up?

Yep, patch is in my next tree.

Patch
diff mbox series

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) {
 		err = nor_erase_prepare(ubi, pnum);
 		if (err)
 			return err;