Re: [PATCH 2/2] nand: pxa3xx: Increase initial buffer size

[Brian Norris <computersforpeace@gmail.com>]

On Mon, Aug 03, 2015 at 11:31:26AM -0300, Ezequiel Garcia wrote:
> The initial buffer is used for the initial commands used to detect
> a flash device (STATUS, READID and PARAM).
> 
> ONFI param page is 256 bytes, and there are three redundant copies
> to be read. JEDEC param page is 512 bytes, and there are also three
> redundant copies to be read. Hence this buffer should be at least
> 512 x 3. This commits rounds the buffer size to 2048.
> 
> Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
> ---
>  drivers/mtd/nand/pxa3xx_nand.c | 15 +++++++++------
>  1 file changed, 9 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/nand/pxa3xx_nand.c b/drivers/mtd/nand/pxa3xx_nand.c
> index 0815f11..9dac28d 100644
> --- a/drivers/mtd/nand/pxa3xx_nand.c
> +++ b/drivers/mtd/nand/pxa3xx_nand.c
> @@ -45,10 +45,13 @@
>  
>  /*
>   * Define a buffer size for the initial command that detects the flash device:
> - * STATUS, READID and PARAM. The largest of these is the PARAM command,
> - * needing 256 bytes.
> + * STATUS, READID and PARAM.
> + * ONFI param page is 256 bytes, and there are three redundant copies
> + * to be read. JEDEC param page is 512 bytes, and there are also three
> + * redundant copies to be read.
> + * Hence this buffer should be at least 512 x 3. Let's pick 2048.
>   */
> -#define INIT_BUFFER_SIZE	256
> +#define INIT_BUFFER_SIZE	2048

Not sure if you're going to run into problems with extended parameter
pages. For one, you don't support NAND_CMD_RNDOUT, it seems.

Brian

>  
>  /* registers and bit definitions */
>  #define NDCR		(0x00) /* Control register */
> @@ -899,14 +902,14 @@ static int prepare_set_command(struct pxa3xx_nand_info *info, int command,
>  		break;
>  
>  	case NAND_CMD_PARAM:
> -		info->buf_count = 256;
> +		info->buf_count = INIT_BUFFER_SIZE;
>  		info->ndcb0 |= NDCB0_CMD_TYPE(0)
>  				| NDCB0_ADDR_CYC(1)
>  				| NDCB0_LEN_OVRD
>  				| command;
>  		info->ndcb1 = (column & 0xFF);
> -		info->ndcb3 = 256;
> -		info->data_size = 256;
> +		info->ndcb3 = INIT_BUFFER_SIZE;
> +		info->data_size = INIT_BUFFER_SIZE;
>  		break;
>  
>  	case NAND_CMD_READID:
> -- 
> 2.4.6
>