Re: [PATCH 3/3] mtd: brcmnand: respect ECC algorithm set by NAND subsystem

Boris Brezillon
2016-04-27T07:55:29Z

On Mon, 25 Apr 2016 22:53:55 -0700
Brian Norris <computersforpeace@gmail.com> wrote:

> From: Brian Norris <computersforpeace@gmail.com>
> Date: Mon, 25 Apr 2016 20:48:02 -0700
> Subject: [PATCH] mtd: brcmnand: respect ECC algorithm set by the NAND
> subsystem
>
> This is more obvious than guessing based on ECC strength. It allows
> using NAND on devices with BCH-1 (e.g. D-Link DIR-885L).
>
> This maintains DT backward compatibility by defaulting to Hamming if a
> 1-bit ECC algorithm is specified without a corresponding algorithm
> selection. i.e., to use BCH-1, you must specify:
>
> nand-ecc-strength = <1>;
> nand-ecc-step-size = <512>;
> nand-ecc-algo = "bch";
>
> Also adds a check to ensure we haven't allowed someone to get by with SW
> ECC. If we want to support SW ECC, we need to refactor some other pieces
> of this driver.
>
> Signed-off-by: Brian Norris <computersforpeace@gmail.com>

Applied, thanks.

Boris

> ---
> drivers/mtd/nand/brcmnand/brcmnand.c | 24 +++++++++++++++++++++++-
> 1 file changed, 23 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/mtd/nand/brcmnand/brcmnand.c b/drivers/mtd/nand/brcmnand/brcmnand.c
> index c3331ffcaffd..b76ad7c0144f 100644
> --- a/drivers/mtd/nand/brcmnand/brcmnand.c
> +++ b/drivers/mtd/nand/brcmnand/brcmnand.c
> @@ -1925,9 +1925,31 @@ static int brcmnand_setup_dev(struct brcmnand_host *host)
> cfg->col_adr_bytes = 2;
> cfg->blk_adr_bytes = get_blk_adr_bytes(mtd->size, mtd->writesize);
>
> + if (chip->ecc.mode != NAND_ECC_HW) {
> + dev_err(ctrl->dev, "only HW ECC supported; selected: %d\n",
> + chip->ecc.mode);
> + return -EINVAL;
> + }
> +
> + if (chip->ecc.algo == NAND_ECC_UNKNOWN) {
> + if (chip->ecc.strength == 1 && chip->ecc.size == 512)
> + /* Default to Hamming for 1-bit ECC, if unspecified */
> + chip->ecc.algo = NAND_ECC_HAMMING;
> + else
> + /* Otherwise, BCH */
> + chip->ecc.algo = NAND_ECC_BCH;
> + }
> +
> + if (chip->ecc.algo == NAND_ECC_HAMMING && (chip->ecc.strength != 1 ||
> + chip->ecc.size != 512)) {
> + dev_err(ctrl->dev, "invalid Hamming params: %d bits per %d bytes\n",
> + chip->ecc.strength, chip->ecc.size);
> + return -EINVAL;
> + }
> +
> switch (chip->ecc.size) {
> case 512:
> - if (chip->ecc.strength == 1) /* Hamming */
> + if (chip->ecc.algo == NAND_ECC_HAMMING)
> cfg->ecc_level = 15;
> else
> cfg->ecc_level = chip->ecc.strength;

--
Boris Brezillon, Free Electrons
Embedded Linux and Kernel engineering