[U-Boot] [PATCH 04/10] mxc_nand: add nand driver for MX2/MX3

[Ivo Clarysse]

Ilya,

On Wed, May 6, 2009 at 8:30 PM, Ilya Yanok <yanok at emcraft.com> wrote:
> Driver for NFC NAND controller found on Freescale's MX2 and MX3
> processors. Ported from Linux. Tested only with i.MX27 but should
> works with other MX2 and MX3 processors too.
[..]
> --- /dev/null
> +++ b/drivers/mtd/nand/mxc_nand.c
> @@ -0,0 +1,891 @@
[...]
> +/* This function polls the NANDFC to wait for the basic operation to
> + * complete by checking the INT bit of config2 register.
> + */
> +static void wait_op_done(struct mxc_nand_host *host, int max_retries,
> +                               uint16_t param, int useirq)
> +{
> +       uint32_t tmp;
> +
> +       while (max_retries-- > 0) {
> +               if (readw(host->regs + NFC_CONFIG2) & NFC_INT) {
> +                       tmp = readw(host->regs + NFC_CONFIG2);
> +                       tmp  &= ~NFC_INT;
> +                       writew(tmp, host->regs + NFC_CONFIG2);
> +                       break;
> +               }
> +               udelay(1);
> +       }
> +       if (max_retries <= 0)
> +               MTDDEBUG(MTD_DEBUG_LEVEL0, "%s(%d): INT not set\n",
> +                               __func__, param);
> +}

As you don't have an interrupt handler (as opposed to the Linux
driver), why keep the 'useirq' parameter ?

[...]
> +static void send_cmd(struct mxc_nand_host *host, uint16_t cmd, int useirq)

Same comment (also renders all 'islast' parameters obsolete).

[...]
> +int board_nand_init(struct nand_chip *this)
> +{
[...]
> +
> +       tmp = readw(host->regs + NFC_CONFIG1);
> +       tmp |= NFC_INT_MSK;
> +       writew(tmp, host->regs + NFC_CONFIG1);

I don't think this is needed on i.MX27, since you don't have an
interrupt handler.
Setting NFC_INT_MSK on i.MX21 will cause NFC_INT in NFC_CONFIG2 to
never get set (and wait_op_done() to always time out)

You might want to have a look at u-boot-v2's MXC nand driver, that one
works on both i.MX21 and i.MX27, without setting NFC_INT_MSK:

      http://git.denx.de/?p=u-boot/u-boot-v2.git;a=blob;f=drivers/nand/nand_imx.c;hb=HEAD

Also, see my post on linux-arm-kernel, "[RFC][PATCH] MXC NAND i.MX21 support":

      http://www.spinics.net/lists/arm-kernel/msg64970.html



Best regards,

Ivo.