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

[Kamal Dasu]

Implemented 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 controller lmitation
where read and corrected data is not transferred to the DMA buffer on ECC
errors. This holds true for ECC correctable errors beyond set threshold.

Fixes: a5d53ad26a8b ("mtd: rawnand: brcmnand: Add support for flash-edu for dma 
transfers")
Signed-off-by: Kamal Dasu <kdasu.k...@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..d7daa83c8a58 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 == 0 && edu_cmd == EDU_CMD_READ) {
+               u64 err_addr = 0;
+
+               /*
+                * check for ecc errors here, subpage ecc erros are
+                * retained in ecc error addr 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_read = 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))
+                       edu_read = 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_read)
+                       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