On Tue, Aug 29, 2023 at 05:29:13PM +0200, Lukasz Majewski wrote:

Hi Oleksij,

quoted

On other hand, since this functionality is not listed as supported by
the KSZ9477 datasheet (No word about IEEE 802.3az Energy Efficient
Ethernet (EEE)) compared to KSZ8565R datasheet (where EEE support is
listed) and it is confirmed to work not stable enough, then it should
be disabled properly.

I've described this problem in more details here:
https://lore.kernel.org/lkml/20230829132429.529283be@wsk/ (local)

-------->8---------
The issue is that ksz9477_config_init() (drivers/net/phy/micrel.c) is
executed AFTER generic phy_probe():
https://elixir.bootlin.com/linux/latest/source/drivers/net/phy/phy_device.c#L3256
in which the EEE advertisement registers are read.

Hence, those registers needs to be cleared earlier - as I do in
ksz9477_setup() in drivers/net/dsa/microchip/ksz9477.

Here the precedence matters ...
----------8<-------------

quoted

The phydev->supported_eee should be cleared.
See ksz9477_get_features().

Removing the linkmod_and() from ksz9477_get_features():
https://elixir.bootlin.com/linux/latest/source/drivers/net/phy/micrel.c#L1408

doesn't help.

Yes, removing linkmod_and() will not should not help. I said, "The
phydev->supported_eee should be cleared."

For example like this:

--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c

@@ -1400,6 +1400,7 @@ static int ksz9131_config_aneg(struct phy_device *phydev)
 
 static int ksz9477_get_features(struct phy_device *phydev)
 {
+       __ETHTOOL_DECLARE_LINK_MODE_MASK(zero) = { 0, };
        int ret;
 
        ret = genphy_read_abilities(phydev);

@@ -1413,7 +1414,7 @@ static int ksz9477_get_features(struct phy_device *phydev)
         * KSZ8563R should have 100BaseTX/Full only.
         */
        linkmode_and(phydev->supported_eee, phydev->supported,
-                    PHY_EEE_CAP1_FEATURES);
+                    zero);
 
        return 0;
 }

You will need to clear it only on KSZ9477 variants with this bug.
This change is tested and it works on my KSZ9477-EVB.

Regards,
Oleksij
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