On Tue, Jun 23, 2020 at 11:49:28AM +0000, Ioana Ciornei wrote:

quoted

This should be added to phylink_mii_c45_pcs_get_state().  There is nothing that
is Lynx PCS specific here.

The USXGMII standard only describes the auto-negotiation word, not the MMD
where this can be found (MMD_VEND2 in this case).
I would not add a generic phylink herper that reads the MMD and also
decodes it.
Maybe a helper that just decodes the USXGMII word read from the
Lynx module - phylink_decode_usxgmii_word(state, lpa) ?

Yes, you're right - as they come from the vendor 2 MMD, there's no
standard.  So yes, just a helper to decode the USXGMII word please.

quoted

quoted

+static void lynx_pcs_get_state_2500basex(struct mdio_device *pcs,
+					 struct phylink_link_state *state) {
+	struct mii_bus *bus = pcs->bus;
+	int addr = pcs->addr;
+	int bmsr, lpa;
+
+	bmsr = mdiobus_read(bus, addr, MII_BMSR);
+	lpa = mdiobus_read(bus, addr, MII_LPA);
+	if (bmsr < 0 || lpa < 0) {
+		state->link = false;
+		return;
+	}
+
+	state->link = !!(bmsr & BMSR_LSTATUS);
+	state->an_complete = !!(bmsr & BMSR_ANEGCOMPLETE);
+	if (!state->link)
+		return;
+
+	state->speed = SPEED_2500;
+	state->pause |= MLO_PAUSE_TX | MLO_PAUSE_RX;

How do you know the other side is using pause frames, or is capable of dealing
with them?

Isn't this done by also looking into the PHY's pause frame bits and
enabling pause frames in the MAC only when both the PCS and the PHY
have flow enabled?

You are assuming that there is a PHY to read that information from.

There may not be a PHY - I have 2500base-X fibre links here, there is
no PHY to read that from, there is only the PCS - but this runs with
the configuration word present, so is not supported by this code (at
least at the moment.)

If there is a PHY, these bits will not be used anyway, so there's no
point setting them.

Yep, will remove. I've gone through the documentation and the register
should be initialized to 0x0001 when in SGMII mode
(as done by phylink_mii_c22_pcs_config()).

Yep, that was actually written referring to the LX2160A documentation.

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