On Wed, Apr 23, 2014 at 09:45:57PM +0200, Marek Vasut wrote:
> On Wednesday, April 23, 2014 at 12:16:50 PM, Huang Shijie wrote:
> > This patch adds the DDR quad read support by the following:
> >
> > [1] add SPI_NOR_DDR_QUAD read mode.
> >
> > [2] add DDR Quad read opcodes:
> > SPINOR_OP_READ_1_4_4_D / SPINOR_OP_READ4_1_4_4_D
> >
> > [3] add set_ddr_quad_mode() to initialize for the DDR quad read.
> > Currently it only works for Spansion NOR.
> >
> > [3] set the dummy with 8 for DDR quad read.
> > The m25p80.c can not support the DDR quad read, the SPI NOR
> > controller can set the dummy value in its driver, such as fsl-quadspi.c.
> >
> > Test this patch for Spansion s25fl128s NOR flash.
> >
> > Signed-off-by: Huang Shijie <b32955@xxxxxxxxxxxxx>
> > ---
> > drivers/mtd/spi-nor/spi-nor.c | 50
> > +++++++++++++++++++++++++++++++++++++++- include/linux/mtd/spi-nor.h |
> > 8 +++++-
> > 2 files changed, 54 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
> > index 1a12f81..e2f69db 100644
> > --- a/drivers/mtd/spi-nor/spi-nor.c
> > +++ b/drivers/mtd/spi-nor/spi-nor.c
> > @@ -74,6 +74,15 @@ static int read_cr(struct spi_nor *nor)
> > static inline int spi_nor_read_dummy_cycles(struct spi_nor *nor)
> > {
> > switch (nor->flash_read) {
> > + case SPI_NOR_DDR_QUAD:
> > + /*
> > + * The m25p80.c can not support the DDR quad read.
> > + * We set the dummy cycles to 8 by default. If the SPI NOR
> > + * controller driver has already set it before call the
> > + * spi_nor_scan(), we just keep it as it is.
> > + */
> > + if (nor->read_dummy)
> > + return nor->read_dummy;
>
> Can the controller set this variable to zero ?
The default value of this variable is zero. It it meaningless to set zero.
The DDR Quad read definitely will use a non-zero dummy.
>
> [...]
>
> > +static int set_ddr_quad_mode(struct spi_nor *nor, u32 jedec_id)
> > +{
> > + int status;
> > +
> > + switch (JEDEC_MFR(jedec_id)) {
> > + case CFI_MFR_AMD: /* Spansion, actually */
> > + status = spansion_quad_enable(nor);
> > + if (status) {
> > + dev_err(nor->dev,
> > + "Spansion DDR quad-read not enabled\n");
> > + return -EINVAL;
>
> Can't you just return status here as well to propagate the failure?
ok.
thanks
Huang Shijie
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