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mtd: brcmnand: Detect sticky ucorr ecc error on dma reads

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This change provides a fix for controller bug where nand
controller could have a possible sticky error after a PIO
followed by a DMA read. The fix retries a read if we see
a uncorr_ecc after read to detect such sticky errors.
The fix applies to only controller version 7.0 and 7.1.

Signed-off-by: Kamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
This commit is contained in:
Kamal Dasu 2016-06-09 17:17:55 -04:00 committed by Boris Brezillon
parent 02b88eea9f
commit bc265323de
1 changed files with 18 additions and 0 deletions
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18
drivers/mtd/nand/brcmnand/brcmnand.c
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@ -1659,9 +1659,11 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
struct brcmnand_controller *ctrl = host->ctrl;
u64 err_addr = 0;
int err;
bool retry = true;
dev_dbg(ctrl->dev, "read %llx -> %p\n", (unsigned long long)addr, buf);
try_dmaread:
brcmnand_write_reg(ctrl, BRCMNAND_UNCORR_COUNT, 0);
if (has_flash_dma(ctrl) && !oob && flash_dma_buf_ok(buf)) {
@ -1682,6 +1684,22 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip,
}
if (mtd_is_eccerr(err)) {
/*
* On controller version and 7.0, 7.1 , DMA read after a
* prior PIO read that reported uncorrectable error,
* the DMA engine captures this error following DMA read
* cleared only on subsequent DMA read, so just retry once
* to clear a possible false error reported for current DMA
* read
*/
if ((ctrl->nand_version == 0x0700) ||
(ctrl->nand_version == 0x0701)) {
if (retry) {
retry = false;
goto try_dmaread;
}
}
/*
* Controller version 7.2 has hw encoder to detect erased page
* bitflips, apply sw verification for older controllers only