[PATCH rtems-libbsd v2 1/2] freebsd/if_cgem: Fail probe for unterminated MII

[Chris Johns]

On 10/7/21 12:53 am, Kinsey Moore wrote:
> When the MII bus is unterminated on unused interfaces, it results in PHY
> read timeouts which manifest as spurious PHYs during the attach call.
> Detect these timeouts during the probe so the device can be ignored.
> ---
>  freebsd/sys/dev/cadence/if_cgem.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/freebsd/sys/dev/cadence/if_cgem.c b/freebsd/sys/dev/cadence/if_cgem.c
> index 34df7ac7..51e0bd6d 100644
> --- a/freebsd/sys/dev/cadence/if_cgem.c
> +++ b/freebsd/sys/dev/cadence/if_cgem.c
> @@ -1955,6 +1955,24 @@ cgem_probe(device_t dev)
>  		return (ENXIO);
>  #endif /* __rtems__ */
>  
> +	struct cgem_softc *sc = device_get_softc(dev);
> +	int val, rid = 0;
> +
> +	/* Check for PHY read timeouts which indicate an unterminated MII bus */
> +	sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
> +					     RF_ACTIVE);
> +
> +	val = cgem_miibus_readreg(dev, 0, MII_BMSR);
> +	if (val == -1) {
> +		bus_release_resource(dev, SYS_RES_MEMORY, &rid,
> +				     sc->mem_res);
> +		sc->mem_res = NULL;
> +		return (ENXIO);
> +	}
> +	bus_release_resource(dev, SYS_RES_MEMORY, &rid,
> +			     sc->mem_res);
> +	sc->mem_res = NULL;

Should this change be in an "#else /* __rtems__ */" section until merged upstream?

Otherwise this change is looking good.

Chris

> +
>  	device_set_desc(dev, "Cadence CGEM Gigabit Ethernet Interface");
>  	return (0);
>  }
>