diff options
Diffstat (limited to 'target/linux/mvebu/patches-3.14/008-nand_warn_weak_ecc_strength.patch')
| -rw-r--r-- | target/linux/mvebu/patches-3.14/008-nand_warn_weak_ecc_strength.patch | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/target/linux/mvebu/patches-3.14/008-nand_warn_weak_ecc_strength.patch b/target/linux/mvebu/patches-3.14/008-nand_warn_weak_ecc_strength.patch new file mode 100644 index 0000000000..09bb72cf4e --- /dev/null +++ b/target/linux/mvebu/patches-3.14/008-nand_warn_weak_ecc_strength.patch @@ -0,0 +1,64 @@ +From 67a9ad9b8a6f6ea76ef8fc484ae49970d72d5534 Mon Sep 17 00:00:00 2001 +From: Ezequiel Garcia <ezequiel.garcia@free-electrons.com> +Date: Wed, 14 May 2014 14:58:06 -0300 +Subject: mtd: nand: Warn the user if the selected ECC strength is too weak + +This commit makes use of the chip->ecc_strength_ds and chip->ecc_step_ds which +contain the datasheet minimum requested ECC strength to produce a noisy warning +if the configured ECC strength is weaker. + +Signed-off-by: Ezequiel Garcia <ezequiel.garcia@free-electrons.com> +Signed-off-by: Brian Norris <computersforpeace@gmail.com> + +--- a/drivers/mtd/nand/nand_base.c ++++ b/drivers/mtd/nand/nand_base.c +@@ -3682,6 +3682,39 @@ int nand_scan_ident(struct mtd_info *mtd + } + EXPORT_SYMBOL(nand_scan_ident); + ++/* ++ * Check if the chip configuration meet the datasheet requirements. ++ ++ * If our configuration corrects A bits per B bytes and the minimum ++ * required correction level is X bits per Y bytes, then we must ensure ++ * both of the following are true: ++ * ++ * (1) A / B >= X / Y ++ * (2) A >= X ++ * ++ * Requirement (1) ensures we can correct for the required bitflip density. ++ * Requirement (2) ensures we can correct even when all bitflips are clumped ++ * in the same sector. ++ */ ++static bool nand_ecc_strength_good(struct mtd_info *mtd) ++{ ++ struct nand_chip *chip = mtd->priv; ++ struct nand_ecc_ctrl *ecc = &chip->ecc; ++ int corr, ds_corr; ++ ++ if (ecc->size == 0 || chip->ecc_step_ds == 0) ++ /* Not enough information */ ++ return true; ++ ++ /* ++ * We get the number of corrected bits per page to compare ++ * the correction density. ++ */ ++ corr = (mtd->writesize * ecc->strength) / ecc->size; ++ ds_corr = (mtd->writesize * chip->ecc_strength_ds) / chip->ecc_step_ds; ++ ++ return corr >= ds_corr && ecc->strength >= chip->ecc_strength_ds; ++} + + /** + * nand_scan_tail - [NAND Interface] Scan for the NAND device +@@ -3891,6 +3924,9 @@ int nand_scan_tail(struct mtd_info *mtd) + ecc->layout->oobavail += ecc->layout->oobfree[i].length; + mtd->oobavail = ecc->layout->oobavail; + ++ /* ECC sanity check: warn noisily if it's too weak */ ++ WARN_ON(!nand_ecc_strength_good(mtd)); ++ + /* + * Set the number of read / write steps for one page depending on ECC + * mode. |