[PATCH v4 1/2] mtd: nand: fix generating over-boundary ECC data when writing
Boris Brezillon
boris.brezillon at free-electrons.com
Wed Aug 31 01:09:11 PDT 2016
On Tue, 30 Aug 2016 20:35:47 +0800
RogerCC Lin <rogercc.lin at mediatek.com> wrote:
> From: RogerCC Lin <rogercc.lin at mediatek.com>
>
> When mtk_ecc_encode() is writing the ECC parity data to the OOB
> region,because each register is 4 bytes in length,but the len's unit is
> in bytes,the operation in the for loop will cross the ECC's boundary.
>
> Signed-off-by: RogerCC Lin <rogercc.lin at mediatek.com>
> ---
> drivers/mtd/nand/mtk_ecc.c | 12 ++++++++----
> 1 files changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/nand/mtk_ecc.c b/drivers/mtd/nand/mtk_ecc.c
> index 25a4fbd..495538e 100644
> --- a/drivers/mtd/nand/mtk_ecc.c
> +++ b/drivers/mtd/nand/mtk_ecc.c
> @@ -366,7 +366,8 @@ int mtk_ecc_encode(struct mtk_ecc *ecc, struct mtk_ecc_config *config,
> u8 *data, u32 bytes)
> {
> dma_addr_t addr;
> - u32 *p, len, i;
> + u8 *p;
> + u32 len, i, val;
> int ret = 0;
>
> addr = dma_map_single(ecc->dev, data, bytes, DMA_TO_DEVICE);
> @@ -392,11 +393,14 @@ int mtk_ecc_encode(struct mtk_ecc *ecc, struct mtk_ecc_config *config,
>
> /* Program ECC bytes to OOB: per sector oob = FDM + ECC + SPARE */
> len = (config->strength * ECC_PARITY_BITS + 7) >> 3;
> - p = (u32 *)(data + bytes);
> + p = data + bytes;
>
> /* write the parity bytes generated by the ECC back to the OOB region */
> - for (i = 0; i < len; i++)
> - p[i] = readl(ecc->regs + ECC_ENCPAR(i));
> + for (i = 0; i < len; i++) {
> + if ((i % 4) == 0)
> + val = readl(ecc->regs + ECC_ENCPAR(i >> 2));
I'm nitpicking, but I'd prefer to have 'i / 4' instead of 'i >> 2' to
be consistent with the 'i % 4' operation, and I also find it clearer.
If you agree, I can do this change while applying the patch, no need to
resend.
> + p[i] = (val >> ((i % 4) * 8)) & 0xff;
> + }
> timeout:
>
> dma_unmap_single(ecc->dev, addr, bytes, DMA_TO_DEVICE);
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