[PATCH RFC net-next] net: pcs: pcs-mtk-lynxi fix mtk_pcs_lynxi_get_state() for 2500base-x

[Russell King (Oracle)]

On Tue, Jan 02, 2024 at 08:44:08AM +0100, Eric Woudstra wrote:
> From: Daniel Golle <daniel at makrotopia.org>
> 
> Need to fix mtk_pcs_lynxi_get_state() in order for the pcs to function
> correctly when the interface is set to 2500base-x, even when
> PHYLINK_PCS_NEG_INBAND_DISABLED is set.

Please describe your setup more fully. What is the link partner on this
2500base-X link?

In PHYLINK_PCS_NEG_INBAND_DISABLED mode, this means that phylink is
operating in inband mode, but Autoneg is clear in the advertisement
mask, meaning Autoneg is disabled and we are using a "fixed" setting.
state->speed and state->duplex should already be initialised.

> When the pcs is set to 2500base-x, the register values are not compatible
> with phylink_mii_c22_pcs_decode_state(). It results in parameters such as
> speed unknown and such. Then the mac/pcs are setup incorrectly and do not
> function.

Since Autoneg is clear, phylink_mii_c22_pcs_decode_state() won't
change state->speed and state->duplex, which should already be
correctly set.

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