[U-Boot] [PATCH v2 3/4] dm: spi: Check cs number before accessing slaves

[Bin Meng]

Hi Jagan,

On Wed, Oct 16, 2019 at 11:21 PM Jagan Teki <jagan at amarulasolutions.com> wrote:
>
> Hi Bin,
>
> On Mon, Sep 9, 2019 at 6:30 PM Bin Meng <bmeng.cn at gmail.com> wrote:
> >
> > Add chip select number check in spi_find_chip_select().
> >
> > Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
> >
> > ---
> >
> > Changes in v2:
> > - move the chip select number check to spi_find_chip_select()
> >
> >  drivers/spi/spi-uclass.c | 45 ++++++++++++++++++++++++++-------------------
> >  include/spi.h            |  3 ++-
> >  2 files changed, 28 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c
> > index 24de0b5..cdeceb5 100644
> > --- a/drivers/spi/spi-uclass.c
> > +++ b/drivers/spi/spi-uclass.c
> > @@ -179,7 +179,32 @@ int spi_chip_select(struct udevice *dev)
> >
> >  int spi_find_chip_select(struct udevice *bus, int cs, struct udevice **devp)
> >  {
> > +       struct dm_spi_ops *ops;
> > +       struct spi_cs_info info;
> >         struct udevice *dev;
> > +       int ret;
> > +
> > +       /*
> > +        * Ask the driver. For the moment we don't have CS info.
> > +        * When we do we could provide the driver with a helper function
> > +        * to figure out what chip selects are valid, or just handle the
> > +        * request.
> > +        */
> > +       ops = spi_get_ops(bus);
> > +       if (ops->cs_info) {
> > +               ret = ops->cs_info(bus, cs, &info);
> > +       } else {
> > +               /*
> > +                * We could assume there is at least one valid chip select.
> > +                * The driver didn't care enough to tell us.
> > +                */
> > +               ret = 0;
> > +       }
> > +
> > +       if (ret) {
> > +               printf("Invalid cs %d (err=%d)\n", cs, ret);
> > +               return ret;
> > +       }
> >
>
> This is breaking 'sf probe' with associated bus and cs on SiFive.

No this does not break anything on SiFive. It enforces the 'sf probe'
to use the correct CS number on SiFive. And something is wrong when CS
is 0 on SiFive.

Regards,
Bin