linux-kernel - Re: [PATCH 2/2] mtd: nand: pxa3xx: Handle "marvell, nand-force-csx" compatible string

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Message-ID: <7493494e-23f6-feed-73e7-59d6819d98db@alliedtelesis.co.nz>
Date:   Wed, 27 Sep 2017 00:54:05 +0000
From:   Kalyan Kinthada <Kalyan.Kinthada@...iedtelesis.co.nz>
To:     Miquel RAYNAL <miquel.raynal@...e-electrons.com>
CC:     "dwmw2@...radead.org" <dwmw2@...radead.org>,
        "computersforpeace@...il.com" <computersforpeace@...il.com>,
        "boris.brezillon@...e-electrons.com" 
        <boris.brezillon@...e-electrons.com>,
        "marek.vasut@...il.com" <marek.vasut@...il.com>,
        "richard@....at" <richard@....at>,
        "cyrille.pitchen@...ev4u.fr" <cyrille.pitchen@...ev4u.fr>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "mark.rutland@....com" <mark.rutland@....com>,
        "ezequiel.garcia@...e-electrons.com" 
        <ezequiel.garcia@...e-electrons.com>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Chris Packham <Chris.Packham@...iedtelesis.co.nz>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] mtd: nand: pxa3xx: Handle "marvell, nand-force-csx"
 compatible string

On 26/09/17 20:18, Miquel RAYNAL wrote:
> Hi Kalyan,
>
> On Tue, 26 Sep 2017 17:17:00 +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.
> I do agree, the driver lacks the support of this bit, which
> looks important when you effectively use the arbiter.
> Nevertheless:
>
> - On PXA (marvell,pxa3xx-nand compatible), there is a ND_ARB_EN bit to
>    enable or disable the arbiter, but there is no FORCE_CSX bit (bit 21
>    of NDCR, the so called Control Register, is reserved).
> - On Armada (marvell,armada370-nand), there is a FORCE_CSX bit, but
>    there is no ND_ARB_EN bit in the NDCR (moved to system registers) and
>    the arbitration is always enabled by default.
>
> I guess you should always set the FORCE_CSX bit when using the armada
> compatible, because it is harmless, right? Thus, you could get rid
> of the new DT property.
Ok. I will make changes to the driver to set FORCE_CSX bit for all
variants of ARMADA370 variants instead of creating a new compatible
string.

I will send a new patch. Kindly ignore these changes.
Thanks for your time Miquel.

Thank You,
Kalyan
>
> Thank you,
> Miquèl
>
>> This commit sets the FORCE_CSX bit to 1 if the compatible
>> string "marvell,nand-force-csx" is enabled in the device tree
>> of the corresponding boards.
>>
>> Signed-off-by: Kalyan Kinthada <kalyan.kinthada@...iedtelesis.co.nz>
>> ---
>>   drivers/mtd/nand/pxa3xx_nand.c                | 6 ++++++
>>   include/linux/platform_data/mtd-nand-pxa3xx.h | 3 +++
>>   2 files changed, 9 insertions(+)
>>
>> diff --git a/drivers/mtd/nand/pxa3xx_nand.c
>> b/drivers/mtd/nand/pxa3xx_nand.c index 85cff68643e0..4ad1f0601930
>> 100644 --- a/drivers/mtd/nand/pxa3xx_nand.c
>> +++ b/drivers/mtd/nand/pxa3xx_nand.c
>> @@ -68,6 +68,7 @@
>>   #define NDCR_PAGE_SZ		(0x1 << 24)
>>   #define NDCR_NCSX		(0x1 << 23)
>>   #define NDCR_ND_MODE		(0x3 << 21)
>> +#define NDCR_FORCE_CSX		(0x1 << 21)
>>   #define NDCR_NAND_MODE   	(0x0)
>>   #define NDCR_CLR_PG_CNT		(0x1 << 20)
>>   #define NFCV1_NDCR_ARB_CNTL	(0x1 << 19)
>> @@ -1464,6 +1465,7 @@ 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;
>> +	info->reg_ndcr |= (pdata->force_csx) ? NDCR_FORCE_CSX : 0;
>>   	info->reg_ndcr |= NDCR_RD_ID_CNT(READ_ID_BYTES);
>>   	info->reg_ndcr |= NDCR_SPARE_EN;
>>   
>> @@ -1498,6 +1500,7 @@ 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;
>> +	info->reg_ndcr |= (pdata->force_csx) ? NDCR_FORCE_CSX : 0;
>>   	info->ndtr0cs0 = nand_readl(info, NDTR0CS0);
>>   	info->ndtr1cs0 = nand_readl(info, NDTR1CS0);
>>   }
>> @@ -1936,6 +1939,9 @@ static int pxa3xx_nand_probe_dt(struct
>> platform_device *pdev) pdata->enable_arbiter = 1;
>>   	if (of_get_property(np, "marvell,nand-keep-config", NULL))
>>   		pdata->keep_config = 1;
>> +	if (of_get_property(np, "marvell,nand-force-csx", NULL))
>> +		/* Ref#: GL-5830741 */
>> +		pdata->force_csx = 1;
>>   	of_property_read_u32(np, "num-cs", &pdata->num_cs);
>>   
>>   	pdev->dev.platform_data = pdata;
>> diff --git a/include/linux/platform_data/mtd-nand-pxa3xx.h
>> b/include/linux/platform_data/mtd-nand-pxa3xx.h index
>> 394d15597dc7..e7f2c8647c0e 100644 ---
>> a/include/linux/platform_data/mtd-nand-pxa3xx.h +++
>> b/include/linux/platform_data/mtd-nand-pxa3xx.h @@ -28,6 +28,9 @@
>> struct pxa3xx_nand_platform_data { /* allow platform code to keep
>> OBM/bootloader defined NFC config */ int	keep_config;
>>   
>> +	/* Force chip select false on busy */
>> +	int	force_csx;
>> +
>>   	/* indicate how many chip selects will be used */
>>   	int	num_cs;
>>   
>
>