Patch "mtd: rawnand: brcmnand: ECC error handling on EDU transfers" has been added to the 5.8-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    mtd: rawnand: brcmnand: ECC error handling on EDU transfers

to the 5.8-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     mtd-rawnand-brcmnand-ecc-error-handling-on-edu-trans.patch
and it can be found in the queue-5.8 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 8e38219a8dc9308c975269c6aff7ebbd1f77a37f
Author: Kamal Dasu <kdasu.kdev@xxxxxxxxx>
Date:   Fri Jun 12 17:29:02 2020 -0400

    mtd: rawnand: brcmnand: ECC error handling on EDU transfers
    
    [ Upstream commit 4551e78ad98add1f16b70cf286d5aad3ce7bcd4c ]
    
    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@xxxxxxxxx>
    Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
    Link: https://lore.kernel.org/linux-mtd/20200612212902.21347-3-kdasu.kdev@xxxxxxxxx
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index ac934a715a194..a4033d32a7103 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -1918,6 +1918,22 @@ 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;
 }
 
@@ -2124,6 +2140,7 @@ 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);
 
@@ -2141,6 +2158,10 @@ 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);
@@ -2188,6 +2209,11 @@ 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;