[U-Boot] [PATCH 2/2] dm: spi: Check cs number before accessing slaves

[Bin Meng]

Hi Jagan,

On Sat, Sep 7, 2019 at 11:45 AM Jagan Teki <jagan at amarulasolutions.com> wrote:
>
> On Thu, Aug 29, 2019 at 7:40 PM Bin Meng <bmeng.cn at gmail.com> wrote:
> >
> > In spi_get_bus_and_cs() only bus number is checked before accessing
> > slaves. We should check cs number as well.
> >
> > Signed-off-by: Bin Meng <bmeng.cn at gmail.com>
> > ---
> >
> >  drivers/spi/spi-uclass.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> >
> > diff --git a/drivers/spi/spi-uclass.c b/drivers/spi/spi-uclass.c
> > index 24de0b5..f633eb5 100644
> > --- a/drivers/spi/spi-uclass.c
> > +++ b/drivers/spi/spi-uclass.c
> > @@ -271,6 +271,7 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode,
> >  {
> >         struct udevice *bus, *dev;
> >         struct dm_spi_slave_platdata *plat;
> > +       struct spi_cs_info info;
> >         bool created = false;
> >         int ret;
> >
> > @@ -283,6 +284,11 @@ int spi_get_bus_and_cs(int busnum, int cs, int speed, int mode,
> >                 printf("Invalid bus %d (err=%d)\n", busnum, ret);
> >                 return ret;
> >         }
> > +       ret = spi_cs_info(bus, cs, &info);
> > +       if (ret) {
> > +               printf("Invalid cs %d (err=%d)\n", cs, ret);
> > +               return ret;
> > +       }
> >         ret = spi_find_chip_select(bus, cs, &dev);
>
> I think it would rather check the cs_info in spi_find_chip_select
> function itself, make more sense.

This routine spi_get_bus_and_cs() has both busnum and cs as
parameters, but only busnum is checked so far. It looks to me more
appropriate to check the cs in spi_get_bus_and_cs() directly, instead
of going into spi_find_chip_select().

Regards,
Bin