[PATCH] [MTD] [NAND] nand_base.c: reset chip first
Ben Dooks
ben-linux at fluff.org
Tue Sep 16 06:10:48 EDT 2008
On Mon, Sep 15, 2008 at 02:37:29PM +0200, Karl Beldan wrote:
> Some chips require a RESET after power-up (e.g. Micron MT29FxGxxxxx).
> The first command sent is NAND_CMD_READID.
> Issue a NAND_CMD_RESET in nand_scan_ident before reading the device id.
> Tested with an MT29F4G08AAC.
This seems sensible to me, we don't really know what state the NAND
chip is in.
Does there need to be a delay after sending the reset command before
attempting to read the chip's identity?
> Signed-off-by: Karl Beldan <karl.beldan at gmail.com>
> ---
> Prior to resetting, the chip gives a correct first ID byte though.
>
>
> diff --git a/drivers/mtd/nand/nand_base.c b/drivers/mtd/nand/nand_base.c
> index d1129ba..2cfac9b 100644
> --- a/drivers/mtd/nand/nand_base.c
> +++ b/drivers/mtd/nand/nand_base.c
> @@ -2318,6 +2318,12 @@ static struct nand_flash_dev
> *nand_get_flash_type(struct mtd_info *mtd,
> /* Select the device */
> chip->select_chip(mtd, 0);
>
> + /*
> + * Reset the chip, required by some chips (e.g. Micron MT29FxGxxxxx)
> + * after power-up
> + */
> + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
> +
> /* Send the command for reading device ID */
> chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
>
> @@ -2488,6 +2494,8 @@ int nand_scan_ident(struct mtd_info *mtd, int maxchips)
> /* Check for a chip array */
> for (i = 1; i < maxchips; i++) {
> chip->select_chip(mtd, i);
> + /* See comment in nand_get_flash_type for reset */
> + chip->cmdfunc(mtd, NAND_CMD_RESET, -1, -1);
> /* Send the command for reading device ID */
> chip->cmdfunc(mtd, NAND_CMD_READID, 0x00, -1);
> /* Read manufacturer and device IDs */
>
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/
--
Ben (ben at fluff.org, http://www.fluff.org/)
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