[PATCH 3/3][NAND][OMAP]: Fixing issue in oamp nand driver in prefetch mode read

[Vimal Singh]

On Wed, Jan 6, 2010 at 7:36 PM, Vimal Singh <vimal.newwork at gmail.com> wrote:
> From 3700088e8da8c890d9e4c6eb626e18287d149b97 Mon Sep 17 00:00:00 2001
> From: Vimal Singh <vimalsingh at ti.com>
> Date: Tue, 5 Jan 2010 16:37:03 +0530
> Subject: [PATCH] NAND: OMAP: Fixing issue in oamp nand driver in
> prefetch mode read
>
> There is a bug in nand prefetch read routine, which comes into effect
> only if nand device is a 16-bit device (as we have in zoom boards).
> This bug is effective only with below combination of conditions:
> 1. nand deivce, in use, is a 16 bit device
> 2. nand driver supports 'subpage' read
> 3. SW ECC is in use
>
> This was not seen old  kernel (ex: .23), because when, in early days,
> we tested this (nand prefetch read in LDP boards) there was no
> 'subpage read' support.
> Later when we had subpage read in (.27) kernel, we had hw ecc enabled
> always in our internal tree. So, we missed this bug.
>
> This patch fixes the issue.
>
> Signed-off-by: Vimal Singh <vimalsingh at ti.com>
> ---
>  drivers/mtd/nand/omap2.c |   11 +++++++----
>  1 files changed, 7 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
> index 16120e2..7df303a 100644
> --- a/drivers/mtd/nand/omap2.c
> +++ b/drivers/mtd/nand/omap2.c
> @@ -295,11 +295,14 @@ static void omap_read_buf_pref(struct mtd_info
> *mtd, u_char *buf, int len)
>        u32 *p = (u32 *)buf;
>
>        /* take care of subpage reads */
> -       for (; len % 4 != 0; ) {
> -               *buf++ = __raw_readb(info->nand.IO_ADDR_R);
> -               len--;
> +       if (len % 4) {
> +               if (info->nand.options & NAND_BUSWIDTH_16)
> +                       omap_read_buf16(mtd, buf, len % 4);
> +               else
> +                       omap_read_buf8(mtd, buf, len % 4);
> +               p = (u32 *) (buf + len % 4);
> +               len -= len % 4;
>        }
> -       p = (u32 *) buf;
>
>        /* configure and start prefetch transfer */
>        ret = gpmc_prefetch_enable(info->gpmc_cs, 0x0, len, 0x0);
> --
> 1.5.5
>

Above patch was line wrapped. Here is the correct one: