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SubjectRE: [PATCH v2 3/4] mtd:spi-nor:fsl-quadspi:Add fast-read mode support
Date
Hi Han,

But I don't think QuadSPI driver need to check the m25p,fast-read property again since spi-nor layer has already done that. Adding the property in flash node should work in the same way.

[Yunhui]: There are three modes in fsl-quadspi driver , fast mode, quad mode, ddr quad read. The last parameter mode of spi_nor_scan() I have to specify . Otherwise, flash is still set to quad mode.
spi-nor.c:

1419 if (mode == SPI_NOR_QUAD && info->flags & SPI_NOR_QUAD_READ) {
1420 ret = set_quad_mode(nor, info);
1421 if (ret) {
1422 dev_err(dev, "quad mode not supported\n");
1423 return ret;
1424 }
1425 nor->flash_read = SPI_NOR_QUAD;
1426 } else if (mode == SPI_NOR_DUAL && info->flags & SPI_NOR_DUAL_READ) {
1427 nor->flash_read = SPI_NOR_DUAL;
1428 }


Thanks
Yunhui
-----Original Message-----
From: Han Xu [mailto:xhnjupt@gmail.com]
Sent: Saturday, February 27, 2016 12:32 AM
To: Yunhui Cui
Cc: Yunhui Cui; dwmw2@infradead.org; computersforpeace@gmail.com; han.xu@freescale.com; linux-mtd@lists.infradead.org; linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org; Yao Yuan
Subject: Re: [PATCH v2 3/4] mtd:spi-nor:fsl-quadspi:Add fast-read mode support

On Thu, Feb 25, 2016 at 08:07:22AM +0000, Yunhui Cui wrote:
> 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;

Did you have some REAL cases using SPI NOR that only supports upto fast-read with Quad SPI driver? Neither fast-read or normal-read, which is actually more general, supported in the driver, just because I didn't see any REAL cases till now.

I didn't run against the patch, although IMO it's not that necessary. But I don't think QuadSPI driver need to check the m25p,fast-read property again since spi-nor layer has already done that. Adding the property in flash node should work in the same way.

>
> Thanks
> Yunhui
>
> -----Original Message-----
> From: Han Xu [mailto:xhnjupt@gmail.com]
> Sent: Thursday, February 18, 2016 2:08 AM
> To: Yunhui Cui
> Cc: dwmw2@infradead.org; computersforpeace@gmail.com;
> han.xu@freescale.com; linux-mtd@lists.infradead.org;
> linux-kernel@vger.kernel.org; linux-arm-kernel@lists.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@freescale.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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