[PATCH v10 04/27] spi: spi-mem: add spi_mem_dtr_supports_op()

[Pratyush Yadav]

On 28/06/21 12:09PM, Jagan Teki wrote:
> On Sun, Jun 27, 2021 at 2:05 PM Pratyush Yadav <p.yadav at ti.com> wrote:
> >
> > On 26/06/21 02:44PM, Jagan Teki wrote:
> > > On Sat, Jun 26, 2021 at 12:47 AM Pratyush Yadav <p.yadav at ti.com> wrote:
> > > >
> > > > spi_mem_default_supports_op() rejects DTR ops by default to ensure that
> > > > the controller drivers that haven't been updated with DTR support
> > > > continue to reject them. It also makes sure that controllers that don't
> > > > support DTR mode at all (which is most of them at the moment) also
> > > > reject them.
> > > >
> > > > This means that controller drivers that want to support DTR mode can't
> > > > use spi_mem_default_supports_op(). Driver authors have to roll their own
> > > > supports_op() function and mimic the buswidth checks. Or even worse,
> > > > driver authors might skip it completely or get it wrong.
> > > >
> > > > Add spi_mem_dtr_supports_op(). It provides a basic sanity check for DTR
> > > > ops and performs the buswidth requirement check. Move the logic for
> > > > checking buswidth in spi_mem_default_supports_op() to a separate
> > > > function so the logic is not repeated twice.
> > > >
> > > > Signed-off-by: Pratyush Yadav <p.yadav at ti.com>
> > > > ---
> > > >  drivers/spi/spi-mem.c | 32 +++++++++++++++++++++++++++++---
> > > >  include/spi-mem.h     |  2 ++
> > > >  2 files changed, 31 insertions(+), 3 deletions(-)
> > > >
> > > > diff --git a/drivers/spi/spi-mem.c b/drivers/spi/spi-mem.c
> > > > index 541cd0e5a7..9c1ede1b61 100644
> > > > --- a/drivers/spi/spi-mem.c
> > > > +++ b/drivers/spi/spi-mem.c
> > > > @@ -145,8 +145,8 @@ static int spi_check_buswidth_req(struct spi_slave *slave, u8 buswidth, bool tx)
> > > >         return -ENOTSUPP;
> > > >  }
> > > >
> > > > -bool spi_mem_default_supports_op(struct spi_slave *slave,
> > > > -                                const struct spi_mem_op *op)
> > > > +static bool spi_mem_check_buswidth(struct spi_slave *slave,
> > > > +                                  const struct spi_mem_op *op)
> > > >  {
> > > >         if (spi_check_buswidth_req(slave, op->cmd.buswidth, true))
> > > >                 return false;
> > > > @@ -164,13 +164,39 @@ bool spi_mem_default_supports_op(struct spi_slave *slave,
> > > >                                    op->data.dir == SPI_MEM_DATA_OUT))
> > > >                 return false;
> > > >
> > > > +       return true;
> > > > +}
> > > > +
> > > > +bool spi_mem_dtr_supports_op(struct spi_slave *slave,
> > > > +                            const struct spi_mem_op *op)
> > > > +{
> > > > +       if (op->cmd.buswidth == 8 && op->cmd.nbytes % 2)
> > > > +               return false;
> > > > +
> > > > +       if (op->addr.nbytes && op->addr.buswidth == 8 && op->addr.nbytes % 2)
> > > > +               return false;
> > > > +
> > > > +       if (op->dummy.nbytes && op->dummy.buswidth == 8 && op->dummy.nbytes % 2)
> > > > +               return false;
> > > > +
> > > > +       if (op->data.dir != SPI_MEM_NO_DATA &&
> > > > +           op->dummy.buswidth == 8 && op->data.nbytes % 2)
> > > > +               return false;
> > > > +
> > > > +       return spi_mem_check_buswidth(slave, op);
> > > > +}
> > > > +EXPORT_SYMBOL_GPL(spi_mem_dtr_supports_op);
> > >
> > > Does this export_symbol is used in U-Boot?
> >
> > It is being used in drivers ported from Linux. I see it being used in
> > spi-mem.c, mtdcore.c, x530_cert_parser.c, nand/core.c, etc. It is
> > defined to an empty macro in include/linux/compat.h.
> 
> Ok, thanks for the details. Somehow we need to refactor the code, I
> believe it would require lot of testing but possible.

Sorry, I don't quite understand what code you want to refactor. Do you 
mean the code in this series? Can you be more specific on what you think 
needs refactoring? Or do you mean a refactor of spi-mem?

-- 
Regards,
Pratyush Yadav
Texas Instruments Inc.