Re: Query regarding Phy loopback support

[Hariprasad Kelam]

On 2025-09-16 at 22:13:20, Andrew Lunn (andrew@xxxxxxx) wrote:
> On Tue, Sep 16, 2025 at 04:48:56PM +0530, Hariprasad Kelam wrote:
> > We're looking for a standard way to configure PHY loopback on a network 
> > interface using common Linux tools like ethtool, ip, or devlink.
> > 
> > Currently, ethtool -k eth0 loopback on enables a generic loopback, but it 
> > doesn't specify if it's an internal, external, or PHY loopback. 
> > Need suggestions to implement this feature in a standard way.
> 
> What actually do you mean by PHY loopback?

The Octeon silicon series supports both MAC (RPM) and PHY (GSERM) loopback 
modes for testing.

We are seeking a solution to support the following loopback types:

MAC Level

Far-end loopback: Ingress data is routed back to egress data (MAC-to-MAC).

Near-end external loopback: Egress traffic is routed back to ingress traffic at the PCS layer.

PHY Level

Near-end digital loopback

Near-end analog loopback

Far-end digital loopback

Far-end analog loopback

We need suggestions on how to enable and manage these specific modes.

Thanks,
Hariprasad k