linux-kernel - RE: [PATCH v2 3/4] mtd:spi-nor:fsl-quadspi:Add fast-read mode support

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Message-ID: <DB5PR0401MB1912C9D041FF2B408652F4CD94A60@DB5PR0401MB1912.eurprd04.prod.outlook.com>
Date:	Thu, 25 Feb 2016 08:07:22 +0000
From:	Yunhui Cui <yunhui.cui@....com>
To:	Han Xu <xhnjupt@...il.com>, Yunhui Cui <B56489@...escale.com>
CC:	"dwmw2@...radead.org" <dwmw2@...radead.org>,
	"computersforpeace@...il.com" <computersforpeace@...il.com>,
	"han.xu@...escale.com" <han.xu@...escale.com>,
	"linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>, Yao Yuan <yao.yuan@....com>
Subject: RE: [PATCH v2 3/4] mtd:spi-nor:fsl-quadspi:Add fast-read mode support

Hi Han,

I have provided the options " m25p,fast-read ", because there are probable some flashes can't support quad mode.
So we should support fast-read mode in our driver. Moreover,  There is a option to select fast-read mode in spi_nor.c :
               /* If we were instantiated by DT, use it */
                 if (of_property_read_bool(np, "m25p,fast-read"))
                         nor->flash_read = SPI_NOR_FAST;

Thanks
Yunhui

-----Original Message-----
From: Han Xu [mailto:xhnjupt@...il.com] 
Sent: Thursday, February 18, 2016 2:08 AM
To: Yunhui Cui
Cc: dwmw2@...radead.org; computersforpeace@...il.com; han.xu@...escale.com; linux-mtd@...ts.infradead.org; linux-kernel@...r.kernel.org; linux-arm-kernel@...ts.infradead.org; Yao Yuan
Subject: Re: [PATCH v2 3/4] mtd:spi-nor:fsl-quadspi:Add fast-read mode support

On Mon, Feb 01, 2016 at 07:30:07PM +0800, Yunhui Cui wrote:
> The qspi driver add generic fast-read mode for different flash 
> venders. There are some different board flash work on different mode, 
> such fast-read, quad-mode.
> So we have to modify the third entrace parameter of spi_nor_scan().
> 
> Signed-off-by: Yunhui Cui <B56489@...escale.com>
> ---
>  drivers/mtd/spi-nor/fsl-quadspi.c | 27 +++++++++++++++++++++------
>  1 file changed, 21 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mtd/spi-nor/fsl-quadspi.c 
> b/drivers/mtd/spi-nor/fsl-quadspi.c
> index 9861290..0a31cb1 100644
> --- a/drivers/mtd/spi-nor/fsl-quadspi.c
> +++ b/drivers/mtd/spi-nor/fsl-quadspi.c
> @@ -389,11 +389,21 @@ static void fsl_qspi_init_lut(struct fsl_qspi *q)
>  	/* Read */
>  	lut_base = SEQID_READ * 4;
>  
> -	qspi_writel(q, LUT0(CMD, PAD1, read_op) | LUT1(ADDR, PAD1, addrlen),
> -			base + QUADSPI_LUT(lut_base));
> -	qspi_writel(q, LUT0(DUMMY, PAD1, read_dm) |
> -		    LUT1(FSL_READ, PAD4, rxfifo),
> -			base + QUADSPI_LUT(lut_base + 1));
> +	if (nor->flash_read == SPI_NOR_FAST) {
> +		qspi_writel(q, LUT0(CMD, PAD1, read_op) |
> +			    LUT1(ADDR, PAD1, addrlen),
> +				base + QUADSPI_LUT(lut_base));
> +		qspi_writel(q,  LUT0(DUMMY, PAD1, read_dm) |
> +			    LUT1(FSL_READ, PAD1, rxfifo),
> +				base + QUADSPI_LUT(lut_base + 1));
> +	} else if (nor->flash_read == SPI_NOR_QUAD) {
> +		qspi_writel(q, LUT0(CMD, PAD1, read_op) |
> +			    LUT1(ADDR, PAD1, addrlen),
> +				base + QUADSPI_LUT(lut_base));
> +		qspi_writel(q, LUT0(DUMMY, PAD1, read_dm) |
> +			    LUT1(FSL_READ, PAD4, rxfifo),
> +				base + QUADSPI_LUT(lut_base + 1));
> +	}
>  
>  	/* Write enable */
>  	lut_base = SEQID_WREN * 4;
> @@ -468,6 +478,7 @@ static int fsl_qspi_get_seqid(struct fsl_qspi *q, 
> u8 cmd)  {
>  	switch (cmd) {
>  	case SPINOR_OP_READ_1_1_4:
> +	case SPINOR_OP_READ_FAST:
>  		return SEQID_READ;
>  	case SPINOR_OP_WREN:
>  		return SEQID_WREN;
> @@ -963,6 +974,7 @@ static int fsl_qspi_probe(struct platform_device *pdev)
>  	struct spi_nor *nor;
>  	struct mtd_info *mtd;
>  	int ret, i = 0;
> +	enum read_mode mode = SPI_NOR_QUAD;
>  
>  	q = devm_kzalloc(dev, sizeof(*q), GFP_KERNEL);
>  	if (!q)
> @@ -1064,7 +1076,10 @@ static int fsl_qspi_probe(struct platform_device *pdev)
>  		/* set the chip address for READID */
>  		fsl_qspi_set_base_addr(q, nor);
>  
> -		ret = spi_nor_scan(nor, NULL, SPI_NOR_QUAD);
> +		ret = of_property_read_bool(np, "m25p,fast-read");
> +		mode = (ret) ? SPI_NOR_FAST : SPI_NOR_QUAD;
> +
> +		ret = spi_nor_scan(nor, NULL, mode);
>  		if (ret)
>  			goto mutex_failed;
>  
I understand you want to provide a more generic read mode, but this is a quad spi driver, I prefer to provide the options, either quad read/quad IO read, or just normal read.
> --
> 2.1.0.27.g96db324
> 
> 
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/

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