[U-Boot] [PATCH v4 1/4] mmc: mmc_spi: Use SPI_XFER_BEGIN and SPI_XFER_END flags

[Anup Patel]

On Tue, Jul 16, 2019 at 1:56 PM Jagan Teki <jagan at amarulasolutions.com> wrote:
>
> On Tue, Jul 16, 2019 at 1:38 PM Anup Patel <anup at brainfault.org> wrote:
> >
> > On Tue, Jul 16, 2019 at 1:05 PM Jagan Teki <jagan at amarulasolutions.com> wrote:
> > >
> > > On Tue, Jul 16, 2019 at 9:52 AM Anup Patel <Anup.Patel at wdc.com> wrote:
> > > >
> > > > Most DM based SPI host controller drivers use SPI_XFER_BEGIN and
> > > > SPI_XFER_END flags to enable/disable slave chip select.
> > > >
> > > > This patch extends MMC SPI driver to pass SPI_XFER_BEGIN flag when
> > > > MMC command is send at start and pass SPI_XFER_END flag using a
> > > > dummy transfer (of bitlen = 0) at the end of MMC command.
> > > >
> > > > Suggested-by: Jagan Teki <jagan at amarulasolutions.com>
> > > > Signed-off-by: Anup Patel <anup.patel at wdc.com>
> > > > ---
> > > >  drivers/mmc/mmc_spi.c | 4 +++-
> > > >  1 file changed, 3 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/mmc/mmc_spi.c b/drivers/mmc/mmc_spi.c
> > > > index f3d687ae80..350812a04b 100644
> > > > --- a/drivers/mmc/mmc_spi.c
> > > > +++ b/drivers/mmc/mmc_spi.c
> > > > @@ -84,7 +84,7 @@ static int mmc_spi_sendcmd(struct udevice *dev,
> > > >         cmdo[4] = cmdarg >> 8;
> > > >         cmdo[5] = cmdarg;
> > > >         cmdo[6] = (crc7(0, &cmdo[1], 5) << 1) | 0x01;
> > > > -       ret = dm_spi_xfer(dev, sizeof(cmdo) * 8, cmdo, NULL, 0);
> > > > +       ret = dm_spi_xfer(dev, sizeof(cmdo) * 8, cmdo, NULL, SPI_XFER_BEGIN);
> > > >         if (ret)
> > > >                 return ret;
> > > >
> > > > @@ -360,6 +360,8 @@ static int dm_mmc_spi_request(struct udevice *dev, struct mmc_cmd *cmd,
> > > >         }
> > > >
> > > >  done:
> > > > +       dm_spi_xfer(dev, 0, NULL, NULL, SPI_XFER_END);
> > > > +
> > >
> > > Look like this driver has several dm_spi_xfer in their won sequence,
> > > have you tried of sending command and buf in same spi_xfer call so
> > > dout and din can be NULL based on the read and write? if ie possible
> > > we can manage the transfer flags in single sub call based on data_len
> > > like drivers/mtd/spi/sf.c does.
> >
> > MMC SPI protocol is very different compared to SPI serial flash.
> >
> > We have to poll for expected byte pattern when waiting for transfer/command
> > to complete. We don't know in-advance how many bytes we will have to read.
>
> Yes, so we begin the transfer and end if successful is it? apart from
> this we also need to provide claim and release calls from here,
> so-that the sifive spi can handle them accordingly otherwise using
> sifive spi may not work with flash.

The claim and release functions are already called at beginning and
end of dm_mmc_spi_request() respectively.