[PATCH RESEND] omap : nand : fix subpage ecc issue with prefetch

[Kishore Kadiyala]

Oops forgot to CC stable at kernel.org, posting again without any changes.

Regards,
Kishore

On Mon, May 9, 2011 at 7:51 PM, Kishore Kadiyala
<kishore.kadiyala at ti.com> wrote:
> When reading/writing a subpage (When HW ECC is not available/enabled)
> for number of bytes not aligned to 4, the mis-aligned bytes are handled
> first (by cpu copy method) before enabling the Prefetch engine to/from
> 'p'(start of buffer 'buf'). Then it reads/writes rest of the bytes with
> the help of Prefetch engine, if available, or again using cpu copy method.
> Currently, reading/writing of rest of bytes, is not done correctly since
> its trying to read/write again to/from begining of buffer 'buf',
> overwriting the mis-aligned bytes.
>
> Read & write using prefetch engine got broken in commit '2c01946c'.
> We never hit a scenario of not getting 'gpmc_prefetch_enable' call
> success. So, problem did not get caught up.
>
> Signed-off-by: Kishore Kadiyala <kishore.kadiyala at ti.com>
> Signed-off-by: Vimal Singh <vimal.newwork at gmail.com>
> Reported-by: Bryan DE FARIA <bdefaria at adeneo-embedded.com>
> ---
>  drivers/mtd/nand/omap2.c |   12 +++++-------
>  1 files changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
> index da9a351..2c8040f 100644
> --- a/drivers/mtd/nand/omap2.c
> +++ b/drivers/mtd/nand/omap2.c
> @@ -263,11 +263,10 @@ static void omap_read_buf_pref(struct mtd_info *mtd, u_char *buf, int len)
>        if (ret) {
>                /* PFPW engine is busy, use cpu copy method */
>                if (info->nand.options & NAND_BUSWIDTH_16)
> -                       omap_read_buf16(mtd, buf, len);
> +                       omap_read_buf16(mtd, (u_char *)p, len);
>                else
> -                       omap_read_buf8(mtd, buf, len);
> +                       omap_read_buf8(mtd, (u_char *)p, len);
>        } else {
> -               p = (u32 *) buf;
>                do {
>                        r_count = gpmc_read_status(GPMC_PREFETCH_FIFO_CNT);
>                        r_count = r_count >> 2;
> @@ -293,7 +292,7 @@ static void omap_write_buf_pref(struct mtd_info *mtd,
>                                                struct omap_nand_info, mtd);
>        uint32_t w_count = 0;
>        int i = 0, ret = 0;
> -       u16 *p;
> +       u16 *p = (u16 *)buf;
>        unsigned long tim, limit;
>
>        /* take care of subpage writes */
> @@ -309,11 +308,10 @@ static void omap_write_buf_pref(struct mtd_info *mtd,
>        if (ret) {
>                /* PFPW engine is busy, use cpu copy method */
>                if (info->nand.options & NAND_BUSWIDTH_16)
> -                       omap_write_buf16(mtd, buf, len);
> +                       omap_write_buf16(mtd, (u_char *)p, len);
>                else
> -                       omap_write_buf8(mtd, buf, len);
> +                       omap_write_buf8(mtd, (u_char *)p, len);
>        } else {
> -               p = (u16 *) buf;
>                while (len) {
>                        w_count = gpmc_read_status(GPMC_PREFETCH_FIFO_CNT);
>                        w_count = w_count >> 1;
> --
> 1.7.4.1
>
>
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