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Commit bc265323 authored by Kamal Dasu's avatar Kamal Dasu Committed by Boris Brezillon
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mtd: brcmnand: Detect sticky ucorr ecc error on dma reads 



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: default avatarKamal Dasu <kdasu.kdev@gmail.com>
Signed-off-by: default avatarBoris Brezillon <boris.brezillon@free-electrons.com>
parent 02b88eea

drivers/mtd/nand/brcmnand/brcmnand.c

+18 −0
Original line number Diff line number Diff line
@@ -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