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SubjectRe: [PATCH v13 09/15] mtd: spi-nor: core: enable octal DTR mode when possible
On 29/09/20 11:26AM, Tudor.Ambarus@microchip.com wrote:
> Hi,
>
> On 9/16/20 3:44 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@ti.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 87c568debf14..6ee93544d72f 100644
> > --- a/drivers/mtd/spi-nor/core.c
> > +++ b/drivers/mtd/spi-nor/core.c
> > @@ -3069,6 +3069,35 @@ 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);
> > + 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/disable Quad I/O if needed.
> > * @nor: pointer to a 'struct spi_nor'
> > @@ -3109,6 +3138,12 @@ 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, true);
>
> Is it possible to enable octal dtr and quad at the same time?
> Maybe an 'if/else if' here depending on the values of nor->read_proto and
> nor->write_proto

No it is not. If you look inside spi_nor_octal_dtr_enable() and
spi_nor_quad_enable(), they both are a no-op if the protocol does not
match. spi_nor_quad_enable() was already doing it this way so I made
spi_nor_octal_dtr_enable() follow suit. So this is effectively an
if-else on the value of nor->read_proto. I don't think an explicit one
is needed.

--
Regards,
Pratyush Yadav
Texas Instruments India

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