[PATCH v4 1/2] mtd: nand: fix generating over-boundary ECC data when writing
RogerCC.Lin
rogercc.lin at mediatek.com
Wed Aug 31 01:19:09 PDT 2016
On Wed, 2016-08-31 at 10:09 +0200, Boris Brezillon wrote:
> 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.
Of course, please apply the patch with 'i / 4',
thank you.
> > + p[i] = (val >> ((i % 4) * 8)) & 0xff;
> > + }
> > timeout:
> >
> > dma_unmap_single(ecc->dev, addr, bytes, DMA_TO_DEVICE);
>
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