Re: [PATCH] mtd/ifc: Fix location of eccstat registers for IFC V1.0

[Boris Brezillon <boris.brezillon@free-electrons.com>]

On Tue, 24 Jan 2017 12:01:22 +0100
<mark.marshall@omicronenergy.com> wrote:

> From: Mark Marshall <mark.marshall@omicronenergy.com>
> 
> The commit 7a654172161c ("mtd/ifc: Add support for IFC controller
> version 2.0") added support for version 2.0 of the IFC controller.
> The version 2.0 controller has the ECC status registers at a different
> location to the previous versions.  This broke the code for IFC all
> versions less than 2.0.
> 
> Correct the fsl_ifc_nand structure so that the ECC status can be read
> from the correct location for both version 1.0 and 2.0 of the controller.
> 
> Cc: stable@vger.kernel.org

Fixes: 7a654172161c ("mtd/ifc: Add support for IFC controller version 2.0")

> Signed-off-by: Mark Marshall <mark.marshall@omicronenergy.com>
> ---
>  drivers/mtd/nand/fsl_ifc_nand.c | 5 ++++-
>  include/linux/fsl_ifc.h         | 8 ++++++--
>  2 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/mtd/nand/fsl_ifc_nand.c b/drivers/mtd/nand/fsl_ifc_nand.c
> index 0a177b1..123c0f8 100644
> --- a/drivers/mtd/nand/fsl_ifc_nand.c
> +++ b/drivers/mtd/nand/fsl_ifc_nand.c
> @@ -260,7 +260,10 @@ static void fsl_ifc_run_command(struct mtd_info *mtd)
>  		int sector_end = sector + chip->ecc.steps - 1;
>  
>  		for (i = sector / 4; i <= sector_end / 4; i++)
> -			eccstat[i] = ifc_in32(&ifc->ifc_nand.nand_eccstat[i]);
> +			eccstat[i] = ifc_in32(
> +				(ctrl->version >= FSL_IFC_VERSION_2_0_0) ?
> +				&ifc->ifc_nand.v2_nand_eccstat[i] :
> +				&ifc->ifc_nand.v1_nand_eccstat[i]);

I'm nitpicking, but how about doing the following to improve
readability:

		__be32 *eccstat_regs;

		if (ctrl->version >= FSL_IFC_VERSION_2_0_0)
			eccstat_regs = &ifc->ifc_nand.v2_nand_eccstat;
		else
			eccstat_regs = &ifc->ifc_nand.v1_nand_eccstat;

		for (i = sector / 4; i <= sector_end / 4; i++)
			eccstat[i] = ifc_in32(&eccstat_regs[i]);

>  
>  		for (i = sector; i <= sector_end; i++) {
>  			errors = check_read_ecc(mtd, ctrl, eccstat, i);
> diff --git a/include/linux/fsl_ifc.h b/include/linux/fsl_ifc.h
> index 3f9778c..c332f0a 100644
> --- a/include/linux/fsl_ifc.h
> +++ b/include/linux/fsl_ifc.h
> @@ -733,8 +733,12 @@ struct fsl_ifc_nand {
>  	__be32 nand_erattr1;
>  	u32 res19[0x10];
>  	__be32 nand_fsr;
> -	u32 res20[0x3];
> -	__be32 nand_eccstat[6];
> +	u32 res20;
> +	/* The V1 nand_eccstat is actually 4 words that overlaps the
> +	 * V2 nand_eccstat.
> +	 */
> +	__be32 v1_nand_eccstat[2];
> +	__be32 v2_nand_eccstat[6];
>  	u32 res21[0x1c];
>  	__be32 nanndcr;
>  	u32 res22[0x2];