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SubjectRe: [PATCH 2/2] net: dsa: microchip: Provide Module 4 KSZ9477 errata (DS80000754C)
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On 8/24/2023 8:48 AM, Lukasz Majewski wrote:
> The KSZ9477 errata points out the link up/down problem when EEE is enabled
> in the device to which the KSZ9477 tries to auto negotiate.
>
> The suggested workaround is to clear advertisement EEE registers
> (accessed as per port MMD one).
>
> Signed-off-by: Lukasz Majewski <lukma@denx.de>
> ---
> drivers/net/dsa/microchip/ksz9477.c | 40 ++++++++++++++++++++++++++++-
> 1 file changed, 39 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/dsa/microchip/ksz9477.c b/drivers/net/dsa/microchip/ksz9477.c
> index cb6aa7c668a8..563f497ba656 100644
> --- a/drivers/net/dsa/microchip/ksz9477.c
> +++ b/drivers/net/dsa/microchip/ksz9477.c
> @@ -1128,6 +1128,44 @@ int ksz9477_enable_stp_addr(struct ksz_device *dev)
> return 0;
> }
>
> +static int ksz9477_errata(struct dsa_switch *ds)
> +{
> + struct ksz_device *dev = ds->priv;
> + u16 val;
> + int p;
> +
> + /* KSZ9477 Errata DS80000754C
> + *
> + * Module 4: Energy Efficient Ethernet (EEE) feature select must be
> + * manually disabled
> + * The EEE feature is enabled by default, but it is not fully
> + * operational. It must be manually disabled through register
> + * controls. If not disabled, the PHY ports can auto-negotiate
> + * to enable EEE, and this feature can cause link drops when linked
> + * to another device supporting EEE.
> + *
> + * Only PHY ports (dsa user) [0-4] need to have the EEE advertisement
> + * bits cleared.
> + */
> +
> + for (p = 0; p < ds->num_ports; p++) {
> + if (!dsa_is_user_port(ds, p))
> + continue;
> +
> + ksz9477_port_mmd_read(dev, p, MMD_DEVICE_ID_EEE_ADV,
> + MMD_EEE_ADV, &val, 1);
> +
> + pr_err("%s: PORT: %d val: 0x%x pc: %d\n", __func__, p, val,
> + ds->num_ports);

Left over debugging?

> +
> + val &= ~(EEE_ADV_100MBIT | EEE_ADV_1GBIT);
> + ksz9477_port_mmd_write(dev, p, MMD_DEVICE_ID_EEE_ADV,
> + MMD_EEE_ADV, &val, 1);
> + }
> +
> + return 0;

You don't propagate any error, so make this return void?
--
Florian

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