[PATCH rtems-libbsd] freebsd/cgem: Use SGMII when necessary

[Kinsey Moore]

On Tue, Nov 1, 2022 at 4:14 PM Chris Johns <chrisj at rtems.org> wrote:

> On 2/11/2022 5:51 am, Kinsey Moore wrote:
> > Certain hardware configurations will always use SGMII instead of RGMII.
> > Apply the appropriate flags for the relevant BSPs.
> > ---
> >  freebsd/sys/dev/cadence/if_cgem.c | 10 ++++++++++
> >  1 file changed, 10 insertions(+)
> >
> > diff --git a/freebsd/sys/dev/cadence/if_cgem.c
> b/freebsd/sys/dev/cadence/if_cgem.c
> > index 3eaaf6b2..9b4cf693 100644
> > --- a/freebsd/sys/dev/cadence/if_cgem.c
> > +++ b/freebsd/sys/dev/cadence/if_cgem.c
> > @@ -1296,6 +1296,16 @@ cgem_config(struct cgem_softc *sc)
> >               CGEM_NET_CFG_FULL_DUPLEX |
> >               CGEM_NET_CFG_SPEED100;
> >
> > +#ifdef __rtems__
> > +#define STRINGIFY(to_str) #to_str
> > +#define BSP_STR(to_str) STRINGIFY(to_str)
> > +     /* Configure the PHYs to use SGMII for particular BSPs */
> > +     if ( 0 == strcmp( BSP_STR(RTEMS_BSP), "xilinx_zynqmp_lp64_cfc400x"
> ) ) {
> > +             net_cfg |= CGEM_NET_CFG_SGMII_EN;
> > +             net_cfg |= CGEM_NET_CFG_PCS_SEL;
> > +     }
>
> This makes it a precedent a cgem device has to be an RTEMS BSP to support
> SGMII.
> I do not think that is a good idea.
>

I don't particularly like this solution either, but I evaluated a few other
options (see below).

>
> Is the simplest solution adding a weak function call asks which mode and
> the
> default call returns RGMII?
>

The downside to that is that none of the tests can operate as expected on a
SGMII-attached-PHY system since the application would be overriding the
weak symbol and the tests wouldn't do that. Another option would be to have
a generic option in RTEMS that specifies the PHY attachment and can be set
in config.ini, but that would appear to be dead code since it's not used
within RTEMS.

As far as I'm aware, the closest analog in LibBSD would be the buildset
configuration, but that seems more like a place to define which modules get
built than a location for configuring hardware.

Kinsey
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