Re: [PATCH v11 04/10] mtd: nand: omap: use DT specified bus-width only for scanning NAND device

[Ezequiel Garcia <ezequiel.garcia@free-electrons.com>]

On Thu, Oct 24, 2013 at 06:20:20PM +0530, Pekon Gupta wrote:
> This patch:
> - calls nand_scan_ident() using bus-width as passed by DT
> - removes double calls to nand_scan_ident(), incase first call fails
>   then omap_nand_probe just returns error.
> 
> Signed-off-by: Pekon Gupta <pekon@ti.com>
> ---
>  drivers/mtd/nand/omap2.c | 21 +++++++++------------
>  1 file changed, 9 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/mtd/nand/omap2.c b/drivers/mtd/nand/omap2.c
> index 5596368..f464321 100644
> --- a/drivers/mtd/nand/omap2.c
> +++ b/drivers/mtd/nand/omap2.c
> @@ -1856,7 +1856,6 @@ static int omap_nand_probe(struct platform_device *pdev)
>  	mtd->name		= dev_name(&pdev->dev);
>  	mtd->owner		= THIS_MODULE;
>  	nand_chip		= &info->nand;
> -	nand_chip->options	= pdata->devsize;
>  	nand_chip->options	|= NAND_SKIP_BBTSCAN;
>  #ifdef CONFIG_MTD_NAND_OMAP_BCH
>  	info->of_node		= pdata->of_node;
> @@ -1904,6 +1903,15 @@ static int omap_nand_probe(struct platform_device *pdev)
>  		nand_chip->chip_delay = 50;
>  	}
>  
> +	/* scan NAND device connected to chip controller */
> +	nand_chip->options |= pdata->devsize & NAND_BUSWIDTH_16;

Hm.. this only works if the device is listed in nand_flash_ids[] array,
so that ONFI detection is not used. To make ONFI detection work I think you
need to do as Brian suggested and use NAND_BUSWIDTH_AUTO.

(Odd: why is there no current user of that auto-width option?)

Anyway, I really think we should fix this now and independently
of the evolution of this ECC DT binding discussion.
That way you can keep sending a smaller ECC DT binding patchset and
make reviewers focus on what's really important in each case.

I have a few fixes (based on your work) and I'll send them now, after
I complete the tests. We can continue our discussion there.
-- 
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com