On Sat, Jul 16, 2022 at 06:37:22PM -0400, Sean Anderson wrote:

On 7/16/22 4:17 PM, Andrew Lunn wrote:

quoted

On Fri, Jul 15, 2022 at 05:59:17PM -0400, Sean Anderson wrote:

quoted

If the phy is configured to use pause-based rate adaptation, ensure that
the link is full duplex with pause frame reception enabled. Note that these
settings may be overridden by ethtool.

Signed-off-by: Sean Anderson <redacted>
---

Changes in v3:
- New

  drivers/net/phy/phylink.c | 4 ++++
  1 file changed, 4 insertions(+)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 7fa21941878e..7f65413aa778 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c

@@ -1445,6 +1445,10 @@ static void phylink_phy_change(struct phy_device *phydev, bool up)
  	pl->phy_state.speed = phy_interface_speed(phydev->interface,
  						  phydev->speed);
  	pl->phy_state.duplex = phydev->duplex;
+	if (phydev->rate_adaptation == RATE_ADAPT_PAUSE) {
+		pl->phy_state.duplex = DUPLEX_FULL;
+		rx_pause = true;
+	}

I would not do this. If the requirements for rate adaptation are not
fulfilled, you should turn off rate adaptation.

A MAC which knows rate adaptation is going on can help out, by not
advertising 10Half, 100Half etc. Autoneg will then fail for modes
where rate adaptation does not work.

OK, so maybe it is better to phylink_warn here. Something along the
lines of "phy using pause-based rate adaptation, but duplex is %s".

quoted

The MAC should also be declaring what sort of pause it supports, so
disable rate adaptation if it does not have async pause.

That's what we do in the previous patch.

The problem is that rx_pause and tx_pause are resolved based on our
advertisement and the link partner's advertisement. However, the link
partner may not support pause frames at all. In that case, we will get
rx_pause and tx_pause as false. However, we still want to enable rx_pause,
because we know that the phy will be emitting pause frames. And of course
the user can always force disable pause frames anyway through ethtool.

If you want the MAC to enable rx_pause, that ought to be handled
separately in the mac_link_up() method, IMHO.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

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