diff mbox series

[1/4] mtd: ubi: Do not zero out EC and VID on ECC-ed NOR flashes

Message ID 87a8c4db9598aa2deb52c41895191b17070ca156.1713154967.git.Takahiro.Kuwano@infineon.com
State Superseded
Delegated to: Jagannadha Sutradharudu Teki
Headers show
Series mtd: Make sure UBIFS does not do multi-pass page programming on flashes that don't support it | expand

Commit Message

Takahiro Kuwano April 15, 2024, 4:33 a.m. UTC 
From: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>

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 Infineon Semper 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: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
---
 drivers/mtd/ubi/build.c | 4 +---
 drivers/mtd/ubi/io.c    | 9 ++++++++-
 2 files changed, 9 insertions(+), 4 deletions(-)

Comments

Tudor Ambarus April 15, 2024, 6:42 a.m. UTC | #1 
Hi, Takahiro,


On 4/15/24 05:33, tkuw584924@gmail.com wrote:
> From: Takahiro Kuwano <Takahiro.Kuwano@infineon.com>
> 
> 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 Infineon Semper 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.
>
I'm not familiar with the u-boot requirements, but I think a good
practice would be to specify if/when a commit follows the upstream linux
implementation. It helps reviewers, gives a peace of mind to the
maintainer(s), and gives credit to the author. If something breaks all
parties can be involved.

This patch replicates the following upstream linux commit:
f669e74be820 ("ubi: Do not zero out EC and VID on ECC-ed NOR flashes")

Acked-by: Tudor Ambarus <tudor.ambarus@linaro.org>

Cheers,
ta
diff mbox series

Patch

diff --git a/drivers/mtd/ubi/build.c b/drivers/mtd/ubi/build.c
index a1941b8eb8..81c1b7bdbc 100644
--- a/drivers/mtd/ubi/build.c
+++ b/drivers/mtd/ubi/build.c
@@ -679,10 +679,8 @@  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 14be95b74b..45699b4a47 100644
--- a/drivers/mtd/ubi/io.c
+++ b/drivers/mtd/ubi/io.c
@@ -563,7 +563,14 @@  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;