From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf0-x243.google.com ([2607:f8b0:400e:c00::243]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1bB7Lb-0004cX-Oo for linux-mtd@lists.infradead.org; Thu, 09 Jun 2016 21:18:40 +0000 Received: by mail-pf0-x243.google.com with SMTP id 62so3549366pfd.3 for ; Thu, 09 Jun 2016 14:18:19 -0700 (PDT) From: Kamal Dasu To: linux-mtd@lists.infradead.org, computersforpeace@gmail.com, boris.brezillon@free-electrons.com Cc: f.fainelli@gmail.com, bcm-kernel-feedback-list@broadcom.com, Kamal Dasu Subject: [V3, 2/2] mtd: brcmnand: Detect sticky ucorr ecc error on dma reads Date: Thu, 9 Jun 2016 17:17:55 -0400 Message-Id: <1465507075-9447-2-git-send-email-kdasu.kdev@gmail.com> In-Reply-To: <1465507075-9447-1-git-send-email-kdasu.kdev@gmail.com> References: <1465507075-9447-1-git-send-email-kdasu.kdev@gmail.com> List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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 --- V3 changes none V2 Changes Restrict controller bug workaround to version 7.0 and 7.1 --- drivers/mtd/nand/brcmnand/brcmnand.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c index 7ee9617..1156495 100644 --- a/drivers/mtd/nand/brcmnand/brcmnand.c +++ b/drivers/mtd/nand/brcmnand/brcmnand.c @@ -1602,9 +1602,11 @@ static int brcmnand_read(struct mtd_info *mtd, struct nand_chip *chip, struct brcmnand_controller *ctrl = host->ctrl; u64 err_addr = 0; int err; + static 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)) { @@ -1626,6 +1628,22 @@ 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 */ -- 1.9.1