Re: [PATCH net-next 1/3] ethtool: (uapi) Add ETHTOOL_PHY_LOOPBACK to PHY tunables

On 11/28/2016 06:14 AM, Andrew Lunn wrote:

On Mon, Nov 28, 2016 at 02:24:30PM +0100, Allan W. Nielsen wrote:

quoted

From: Raju Lakkaraju <redacted>

3 types of PHY loopback are supported.
i.e. Near-End Loopback, Far-End Loopback and External Loopback.

Hi Allan

Is this integrated with ethtool --test? You only want the PHY to go
into loopback mode when running ethtool --test external_lb or maybe
ethtool --test offline.

What i think should happen is that this tunable sets the mode the PHY
will go into when loopback is enabled. It does not however enable
loopback. It is running ethtool --test which actually enables the
loopback, probably by setting BMCR_LOOPBACK. Once the test is
finished, the bit is cleared and the PHY goes back into normal
operation.

Agreed with Andrew, there needs to be a tight coupling between the
existing ethtool test infrastructure, and how to perform PHY loopback
testing.

It makes sense for the PHY drivers to be able to implement specific
loopback/test mode, but we need to clarify how these get called from
ethtool --test for instance, and if the Ethernet MAC driver needs to do
something specific as well.
-- 
Florian