[PATCH v2 0/2] mtd: rawnand: brcmnand: ECC error handling on EDU transfers

[PATCH v2 0/2] mtd: rawnand: brcmnand: ECC error handling on EDU transfers

[Kamal Dasu]

V2 changes:

"mtd: rawnand: brcmnand: Don't default to edu transfer"
- no change

"mtd: rawnand: brcmnand: ECC error handling on EDU transfers"
- Fix typos in commit message and clarify bitflips threhold use
- Fix typos in code comments
- change bool edu_read to bool edu_err in brcmnand_read()

Kamal Dasu (2):
  mtd: rawnand: brcmnand: Don't default to edu transfer
  mtd: rawnand: brcmnand: ECC error handling on EDU transfers

 drivers/mtd/nand/raw/brcmnand/brcmnand.c | 31 ++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

-- 
2.17.1

[PATCH v2 1/2] mtd: rawnand: brcmnand: Don't default to edu transfer

[Kamal Dasu]

When flash-dma is absent do not default to using flash-edu.
Make sure flash-edu is enabled before setting EDU transfer
function.

Fixes: a5d53ad26a8b ("mtd: rawnand: brcmnand: Add support for flash-edu for dma transfers")
Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
---
 drivers/mtd/nand/raw/brcmnand/brcmnand.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index 8f9ffb46a09f..0c1d6e543586 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -2953,8 +2953,9 @@ int brcmnand_probe(struct platform_device *pdev, struct brcmnand_soc *soc)
 		if (ret < 0)
 			goto err;
 
-		/* set edu transfer function to call */
-		ctrl->dma_trans = brcmnand_edu_trans;
+		if (has_edu(ctrl))
+			/* set edu transfer function to call */
+			ctrl->dma_trans = brcmnand_edu_trans;
 	}
 
 	/* Disable automatic device ID config, direct addressing */
-- 
2.17.1

[PATCH v2 2/2] mtd: rawnand: brcmnand: ECC error handling on EDU transfers

[Kamal Dasu]

Implement ECC correctable and uncorrectable error handling for EDU
reads. If ECC correctable bitflips are encountered on EDU transfer,
read page again using PIO. This is needed due to a NAND controller
limitation where corrected data is not transferred to the DMA buffer
on ECC error. This applies to ECC correctable errors that are reported
by the controller hardware based on set number of bitflips threshold in
the controller threshold register, bitflips below the threshold are
corrected silently and are not reported by the controller hardware.

Fixes: a5d53ad26a8b ("mtd: rawnand: brcmnand: Add support for flash-edu for dma transfers")
Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
---
 drivers/mtd/nand/raw/brcmnand/brcmnand.c | 26 ++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index 0c1d6e543586..131d5d6e2626 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -1855,6 +1855,22 @@ static int brcmnand_edu_trans(struct brcmnand_host *host, u64 addr, u32 *buf,
 	edu_writel(ctrl, EDU_STOP, 0); /* force stop */
 	edu_readl(ctrl, EDU_STOP);
 
+	if (!ret && edu_cmd == EDU_CMD_READ) {
+		u64 err_addr = 0;
+
+		/*
+		 * check for ECC errors here, subpage ECC errors are
+		 * retained in ECC error address register
+		 */
+		err_addr = brcmnand_get_uncorrecc_addr(ctrl);
+		if (!err_addr) {
+			err_addr = brcmnand_get_correcc_addr(ctrl);
+			if (err_addr)
+				ret = -EUCLEAN;
+		} else
+			ret = -EBADMSG;
+	}
+
 	return ret;
 }
 
@@ -2058,6 +2074,7 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
 	u64 err_addr = 0;
 	int err;
 	bool retry = true;
+	bool edu_err = false;
 
 	dev_dbg(ctrl->dev, "read %llx -> %p\n", (unsigned long long)addr, buf);
 
@@ -2075,6 +2092,10 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
 			else
 				return -EIO;
 		}
+
+		if (has_edu(ctrl) && err_addr)
+			edu_err = true;
+
 	} else {
 		if (oob)
 			memset(oob, 0x99, mtd->oobsize);
@@ -2122,6 +2143,11 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
 	if (mtd_is_bitflip(err)) {
 		unsigned int corrected = brcmnand_count_corrected(ctrl);
 
+		/* in case of EDU correctable error we read again using PIO */
+		if (edu_err)
+			err = brcmnand_read_by_pio(mtd, chip, addr, trans, buf,
+						   oob, &err_addr);
+
 		dev_dbg(ctrl->dev, "corrected error at 0x%llx\n",
 			(unsigned long long)err_addr);
 		mtd->ecc_stats.corrected += corrected;
-- 
2.17.1

Re: [PATCH v2 2/2] mtd: rawnand: brcmnand: ECC error handling on EDU transfers

[Miquel Raynal]

On Fri, 2020-06-12 at 21:29:02 UTC, Kamal Dasu wrote:
> Implement ECC correctable and uncorrectable error handling for EDU
> reads. If ECC correctable bitflips are encountered on EDU transfer,
> read page again using PIO. This is needed due to a NAND controller
> limitation where corrected data is not transferred to the DMA buffer
> on ECC error. This applies to ECC correctable errors that are reported
> by the controller hardware based on set number of bitflips threshold in
> the controller threshold register, bitflips below the threshold are
> corrected silently and are not reported by the controller hardware.
> 
> Fixes: a5d53ad26a8b ("mtd: rawnand: brcmnand: Add support for flash-edu for dma transfers")
> Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next, thanks.

Miquel

Re: [PATCH v2 1/2] mtd: rawnand: brcmnand: Don't default to edu transfer

[Miquel Raynal]

On Fri, 2020-06-12 at 21:29:01 UTC, Kamal Dasu wrote:
> When flash-dma is absent do not default to using flash-edu.
> Make sure flash-edu is enabled before setting EDU transfer
> function.
> 
> Fixes: a5d53ad26a8b ("mtd: rawnand: brcmnand: Add support for flash-edu for dma transfers")
> Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>

Applied to https://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux.git nand/next, thanks.

Miquel