linux-kernel - Re: [PATCH v14 08/15] mtd: spi-nor: core: enable octal DTR mode when possible

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Message-ID: <20201001084206.ma4beblucowmtwgq@ti.com>
Date:   Thu, 1 Oct 2020 14:12:08 +0530
From:   Pratyush Yadav <p.yadav@...com>
To:     <Tudor.Ambarus@...rochip.com>
CC:     <miquel.raynal@...tlin.com>, <richard@....at>, <vigneshr@...com>,
        <linux-mtd@...ts.infradead.org>, <linux-kernel@...r.kernel.org>,
        <nsekhar@...com>, <boris.brezillon@...labora.com>
Subject: Re: [PATCH v14 08/15] mtd: spi-nor: core: enable octal DTR mode when
 possible

On 01/10/20 08:09AM, Tudor.Ambarus@...rochip.com wrote:
> On 9/30/20 9:57 PM, Pratyush Yadav wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe
> > 
> > Allow flashes to specify a hook to enable octal DTR mode. Use this hook
> > whenever possible to get optimal transfer speeds.
> > 
> > Signed-off-by: Pratyush Yadav <p.yadav@...com>
> > ---
> >  drivers/mtd/spi-nor/core.c | 35 +++++++++++++++++++++++++++++++++++
> >  drivers/mtd/spi-nor/core.h |  2 ++
> >  2 files changed, 37 insertions(+)
> > 
> > diff --git a/drivers/mtd/spi-nor/core.c b/drivers/mtd/spi-nor/core.c
> > index 73a26e7e32c2..6b54a923002a 100644
> > --- a/drivers/mtd/spi-nor/core.c
> > +++ b/drivers/mtd/spi-nor/core.c
> > @@ -3068,6 +3068,35 @@ static int spi_nor_init_params(struct spi_nor *nor)
> >         return 0;
> >  }
> > 
> > +/** spi_nor_octal_dtr_enable() - enable Octal DTR I/O if needed
> > + * @nor:                 pointer to a 'struct spi_nor'
> > + * @enable:              whether to enable or disable Octal DTR
> > + *
> > + * Return: 0 on success, -errno otherwise.
> > + */
> > +static int spi_nor_octal_dtr_enable(struct spi_nor *nor, bool enable)
> > +{
> > +       int ret;
> > +
> > +       if (!nor->params->octal_dtr_enable)
> > +               return 0;
> > +
> > +       if (!(nor->read_proto == SNOR_PROTO_8_8_8_DTR &&
> > +             nor->write_proto == SNOR_PROTO_8_8_8_DTR))
> > +               return 0;
> > +
> > +       ret = nor->params->octal_dtr_enable(nor, enable);
> 
> Ideally patch 9/15 and 10/15 should have been before 8/15. We should deny
> the access to octal dtr enable for NV flashes since moment 0.

Ok. I'll re-order them.
 
> > +       if (ret)
> > +               return ret;
> > +
> > +       if (enable)
> > +               nor->reg_proto = SNOR_PROTO_8_8_8_DTR;
> > +       else
> > +               nor->reg_proto = SNOR_PROTO_1_1_1;
> > +
> > +       return 0;
> > +}
> > +
> >  /**
> >   * spi_nor_quad_enable() - enable Quad I/O if needed.
> >   * @nor:                pointer to a 'struct spi_nor'
> > @@ -3107,6 +3136,12 @@ static int spi_nor_init(struct spi_nor *nor)
> >  {
> >         int err;
> > 
> > +       err = spi_nor_octal_dtr_enable(nor, true);
> > +       if (err) {
> > +               dev_dbg(nor->dev, "octal mode not supported\n");
> > +               return err;
> > +       }
> > +
> >         err = spi_nor_quad_enable(nor);
> >         if (err) {
> >                 dev_dbg(nor->dev, "quad mode not supported\n");
> > diff --git a/drivers/mtd/spi-nor/core.h b/drivers/mtd/spi-nor/core.h
> > index 9a33c8d07335..5cfe2db9ee13 100644
> > --- a/drivers/mtd/spi-nor/core.h
> > +++ b/drivers/mtd/spi-nor/core.h
> > @@ -203,6 +203,7 @@ struct spi_nor_locking_ops {
> >   *                      higher index in the array, the higher priority.
> >   * @erase_map:         the erase map parsed from the SFDP Sector Map Parameter
> >   *                      Table.
> > + * @octal_dtr_enable:  enables SPI NOR octal DTR mode.
> >   * @quad_enable:       enables SPI NOR quad mode.
> >   * @set_4byte_addr_mode: puts the SPI NOR in 4 byte addressing mode.
> >   * @convert_addr:      converts an absolute address into something the flash
> > @@ -226,6 +227,7 @@ struct spi_nor_flash_parameter {
> > 
> >         struct spi_nor_erase_map        erase_map;
> > 
> > +       int (*octal_dtr_enable)(struct spi_nor *nor, bool enable);
> >         int (*quad_enable)(struct spi_nor *nor);
> >         int (*set_4byte_addr_mode)(struct spi_nor *nor, bool enable);
> >         u32 (*convert_addr)(struct spi_nor *nor, u32 addr);
> > --
> > 2.28.0
> > 
> 

-- 
Regards,
Pratyush Yadav
Texas Instruments India