[U-Boot] [PATCH 1/4] spl: nand: simple: replace readb() with chip specific read_buf()

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hello Vladimir,

On Thu, 16 Jul 2015 02:33:45 +0300, Vladimir Zapolskiy <vz@mleia.com>
wrote:
> Some NAND controllers define custom functions to read data out,
> respect this in order to correctly support bad block handling in
> simple SPL NAND framework.
> 
> NAND controller specific read_buf() is used even to read 1 byte in
> case of connected 8-bit NAND device, it turns out that read_byte()
> may become outdated.
> 
> Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
> ---
>  drivers/mtd/nand/nand_spl_simple.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/nand_spl_simple.c b/drivers/mtd/nand/nand_spl_simple.c
> index 700ca32..e69f662 100644
> --- a/drivers/mtd/nand/nand_spl_simple.c
> +++ b/drivers/mtd/nand/nand_spl_simple.c
> @@ -115,6 +115,7 @@ static int nand_command(int block, int page, uint32_t offs,
>  static int nand_is_bad_block(int block)
>  {
>  	struct nand_chip *this = mtd.priv;
> +	u_char bb_data[2];
>  
>  	nand_command(block, 0, CONFIG_SYS_NAND_BAD_BLOCK_POS,
>  		NAND_CMD_READOOB);
> @@ -123,10 +124,12 @@ static int nand_is_bad_block(int block)
>  	 * Read one byte (or two if it's a 16 bit chip).
>  	 */
>  	if (this->options & NAND_BUSWIDTH_16) {
> -		if (readw(this->IO_ADDR_R) != 0xffff)
> +		this->read_buf(&mtd, bb_data, 2);
> +		if (bb_data[0] != 0xff || bb_data[1] != 0xff)
>  			return 1;
>  	} else {
> -		if (readb(this->IO_ADDR_R) != 0xff)
> +		this->read_buf(&mtd, bb_data, 1);
> +		if (bb_data[0] != 0xff)
>  			return 1;
>  	}
>  
> -- 
> 2.1.4
> 

The way you describe this patch, it looks like a bug that should have
bitten way more boards than lpc32xx. Did you have a look at some other
boards to see why this did not affect them? Conversively, what is the
actual failure scenario that led you to writing this patch? 

Amicalement,
-- 
Albert.