linux-kernel - Re: [PATCH v3 1/1] mtd: nand: pxa3xx: Set FORCE

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Date:   Thu, 5 Oct 2017 09:41:38 +0200
From:   Miquel RAYNAL <miquel.raynal@...e-electrons.com>
To:     Kalyan Kinthada <kalyan.kinthada@...iedtelesis.co.nz>
Cc:     dwmw2@...radead.org, computersforpeace@...il.com,
        boris.brezillon@...e-electrons.com, marek.vasut@...il.com,
        richard@....at, cyrille.pitchen@...ev4u.fr, robh+dt@...nel.org,
        mark.rutland@....com, ezequiel.garcia@...e-electrons.com,
        devicetree@...r.kernel.org, chris.packham@...iedtelesis.co.nz,
        linux-mtd@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/1] mtd: nand: pxa3xx: Set FORCE_CSX bit to
 ARMADA370 variants.

Hello Kalyan,

On Thu, 28 Sep 2017 13:57:56 +1300
Kalyan Kinthada <kalyan.kinthada@...iedtelesis.co.nz> wrote:

> When the arbitration between NOR and NAND flash is enabled
> the <FORCE_CSX> field bit[21] in the Data Flash Control Register
> needs to be set to 1 according to guidleine GL-5830741 mentioned

Typo: guideline ^

> in Marvell Errata document MV-S501377-00, Rev. D.

Thanks for that, I checked it.

> 
> This commit sets the FORCE_CSX bit to 1 for all
> ARMADA370 variants as the arbitration is always enabled by default.
> This change does not apply for pxa3xx variants because the FORCE_CSX
> bit does not exist/reserved on the NFCv1.

Sorry to bother you again but I am reworking the pxa3xx_nand driver and
so I would like to deeply understand why this is needed because I will
have to integrate it in my work too.

So please tell me what is your setup, do you really use NAND/NOR
arbitration? Do you have not-Don't Care CS NAND chips? I have some
doubts because even if the spec precises in the NAND controller chapter
that arbitration is always enabled by default, the bit 27 (NfArbiterEn)
in the SoC Device Multiplex Register at offset 0x00018208 is actually
at 0 by default (disabled). Did you enable this bit manually ? I
checked with devmem on my setup and this bit was unset.

Thank you for your time,
Miquèl

> 
> The NDCR_ND_MODE conflicts with the new NDCR_FORCE_CSX but is unused
> so remove it along with NDCR_NAND_MODE.
> 
> Signed-off-by: Kalyan Kinthada <kalyan.kinthada@...iedtelesis.co.nz>
> ---



>  drivers/mtd/nand/pxa3xx_nand.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/pxa3xx_nand.c
> b/drivers/mtd/nand/pxa3xx_nand.c index 85cff68643e0..a6a7a5af7bed
> 100644 --- a/drivers/mtd/nand/pxa3xx_nand.c
> +++ b/drivers/mtd/nand/pxa3xx_nand.c
> @@ -67,8 +67,7 @@
>  #define NDCR_DWIDTH_M		(0x1 << 26)
>  #define NDCR_PAGE_SZ		(0x1 << 24)
>  #define NDCR_NCSX		(0x1 << 23)
> -#define NDCR_ND_MODE		(0x3 << 21)
> -#define NDCR_NAND_MODE   	(0x0)
> +#define NDCR_FORCE_CSX		(0x1 << 21)
>  #define NDCR_CLR_PG_CNT		(0x1 << 20)
>  #define NFCV1_NDCR_ARB_CNTL	(0x1 << 19)
>  #define NFCV2_NDCR_STOP_ON_UNCOR	(0x1 << 19)
> @@ -1464,6 +1463,9 @@ static int pxa3xx_nand_config_ident(struct
> pxa3xx_nand_info *info) info->chunk_size = PAGE_CHUNK_SIZE;
>  	info->reg_ndcr = 0x0; /* enable all interrupts */
>  	info->reg_ndcr |= (pdata->enable_arbiter) ? NDCR_ND_ARB_EN :
> 0;
> +	/* Set FORCE_CSX bit for all ARMADA370 Variants. Ref#:
> GL-5830741 */
> +	if (info->variant == PXA3XX_NAND_VARIANT_ARMADA370)
> +		info->reg_ndcr |= NDCR_FORCE_CSX;
>  	info->reg_ndcr |= NDCR_RD_ID_CNT(READ_ID_BYTES);
>  	info->reg_ndcr |= NDCR_SPARE_EN;
>  
> @@ -1498,6 +1500,9 @@ static void pxa3xx_nand_detect_config(struct
> pxa3xx_nand_info *info) info->reg_ndcr = ndcr &
>  		~(NDCR_INT_MASK | NDCR_ND_ARB_EN |
> NFCV1_NDCR_ARB_CNTL); info->reg_ndcr |= (pdata->enable_arbiter) ?
> NDCR_ND_ARB_EN : 0;
> +	/* Set FORCE_CSX bit for all ARMADA370 Variants. Ref#:
> GL-5830741 */
> +	if (info->variant == PXA3XX_NAND_VARIANT_ARMADA370)
> +		info->reg_ndcr |= NDCR_FORCE_CSX;
>  	info->ndtr0cs0 = nand_readl(info, NDTR0CS0);
>  	info->ndtr1cs0 = nand_readl(info, NDTR1CS0);
>  }



-- 
Miquel Raynal, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com