[U-Boot] [PATCH v5] Corrupted NAND Flash access on KARO TX25 modules.

[Benoît Thébaudeau]

Dear Daniel,

On Thu, Aug 2, 2012 at 01:17:07 PM, Daniel Gachet wrote:
> The mxc_nand driver uses the symmetric mode to access the NAND Flash,
> but the
> devices populated on the KARO TX25 only support ann asymmetic mode
> (MX25: bit 8 within NAND_FLAHS_CONFIG1 register cleared).
> 
> This patch enables to selected the NAND Flash access mode with the
> configuration flag CONFIG_SYS_NAND_MXC_NFC_TWO_CYCLES.
> 
> Signed-off-by: Daniel Gachet <daniel.gachet at hefr.ch>
> ---
>  drivers/mtd/nand/mxc_nand.c |   13 +++++++++++++
>  include/configs/tx25.h      |    1 +
>  2 files changed, 14 insertions(+)
> 
> diff --git a/drivers/mtd/nand/mxc_nand.c
> b/drivers/mtd/nand/mxc_nand.c
> index 936186f..08fbb12 100644
> --- a/drivers/mtd/nand/mxc_nand.c
> +++ b/drivers/mtd/nand/mxc_nand.c
> @@ -48,6 +48,17 @@
>   * 	Reading or writing a 2K or 4K page requires only 1 FDI/FDO
>   cycle.
>   *      Also some of registers are moved and/or changed meaning as
>   seen below.
>   */
> +/*
> + * NAND Flash access mode on MX25
> + *
> + * The MX25 NAND Flash Controller supports two modes to access the
> Flash:
> + *   a) symmetric mode (one Flash clock cycle per access) or
> + *   b) asymmetric mode (two Flash clock cycles per access)
> + *
> + * By default the NAND Flash Controller is configured in the
> symmetric mode.
> + * To select the asymmetric mode, the configuration option
> + * CONFIG_SYS_NAND_MXC_NFC_TWO_CYCLES has to be selected.
> + */
>  #if defined(CONFIG_MX31) || defined(CONFIG_MX27)
>  #define MXC_NFC_V1
>  #elif defined(CONFIG_MX25) || defined(CONFIG_MX35)
> @@ -1290,7 +1301,9 @@ static void mxc_setup_config1(void)
>  	uint16_t tmp;
>  
>  	tmp = readw(&host->regs->nfc_config1);
> +#ifndef CONFIG_SYS_NAND_MXC_NFC_TWO_CYCLES
>  	tmp |= NFC_ONE_CYCLE;
> +#endif
>  	tmp |= NFC_4_8N_ECC;
>  	writew(tmp, &host->regs->nfc_config1);
>  	if (host->pagesize_2k)
> diff --git a/include/configs/tx25.h b/include/configs/tx25.h
> index 6821528..8fa51cb 100644
> --- a/include/configs/tx25.h
> +++ b/include/configs/tx25.h
> @@ -109,6 +109,7 @@
>  /* NAND */
>  #define CONFIG_NAND_MXC
>  #define CONFIG_NAND_MXC_V1_1
> +#define CONFIG_SYS_NAND_MXC_NFC_TWO_CYCLES /* 2 cycles to access
> NAND Flash */
>  #define CONFIG_MXC_NAND_REGS_BASE	(0xBB000000)
>  #define CONFIG_SYS_MAX_NAND_DEVICE	1
>  #define CONFIG_SYS_NAND_BASE		(0xBB000000)
> --
> 1.7.9.5
> 
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Why don't you simply add a factor of two to the CCM NFC divider in
lowlevel_init.S?

Best regards,
Benoît