[U-Boot] [PATCH v2] Correct corrupted NAND Flash access on KARO TX25 modules

[stefano babic <sbabic@denx.de>]

Am 02/04/2012 22:55, schrieb Gachet Daniel:
> This patch v2 correct corrupted data while reading NAND flash modules on the KARO TX25 module.
> 

Hi Daniel,

> The current version of the mxc_nand driver uses the symmetric mode to access the NAND flash, but the devices populated on the KARO TX25 only support an asymmetric mode (i.MX25: bit 8  within NAND_FLASH_CONFIG1 register cleared). 
> 
> To solve the problem in a generic way, the proposition is to define a specific value for that bit, CONFIG_NAND_MXC_NFC_ONE_CYCLE. This value could be defined in the specific board configuration file (./include/configs/...). Short description:
> 
> CONFIG_NAND_MXC_NFC_ONE_CYCLE enables to specify how to access NAND flash on the i.MX25 CPU.
> If CONFIG_NAND_MXC_NFC_ONE_CYCLE is defined, a one-clock cycle will be used to access the NAND flash (symmetric mode); otherwise a two-clock cycle will be used (asymmetric mode).
> 
> Signed-off-by: Daniel Gachet <daniel.gachet@hefr.ch>
> Cc: stefano babic <sbabic@denx.de>
> 
> diff -upr drivers/mtd/nand/mxc_nand.c drivers/mtd/nand/mxc_nand.c
> --- drivers/mtd/nand/mxc_nand.c	2011-12-23 20:25:35.000000000 +0100
> +++ drivers/mtd/nand/mxc_nand.c	2012-04-02 22:30:13.000000000 +0200
> @@ -1290,7 +1290,9 @@ static void mxc_setup_config1(void)
>  	uint16_t tmp;
>  
>  	tmp = readw(&host->regs->nfc_config1);
> +#ifdef CONFIG_NAND_MXC_NFC_ONE_CYCLE
>  	tmp |= NFC_ONE_CYCLE;
> +#endif

This is not correct. You invert the logic, making as default your board.
But this breaks other boards because none of them set this switch.

To complete your patch you should:
- use an inverted logic, letting as default the current behavior and
modifying the behavior only for your board.
- add the config switch to your board configuration file, that is tx25.h
- add a description in the README file for your new configuration switch

Best regards,
Stefano Babic

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