Re: [RFC PATCH v3 net-next 2/6] net: phylink: introduce a generic method for querying PHY in-band autoneg capability

On Wed, Sep 22, 2021 at 09:48:28PM +0000, Vladimir Oltean wrote:

On Thu, Sep 23, 2021 at 12:31:16AM +0300, Vladimir Oltean wrote:

quoted

On Wed, Sep 22, 2021 at 10:22:19PM +0100, Russell King (Oracle) wrote:

quoted

On Wed, Sep 22, 2021 at 09:14:42PM +0300, Vladimir Oltean wrote:

quoted

+static unsigned int phylink_fixup_inband_aneg(struct phylink *pl,
+					      struct phy_device *phy,
+					      unsigned int mode)
+{
+	int ret;
+
+	ret = phy_validate_inband_aneg(phy, pl->link_interface);
+	if (ret == PHY_INBAND_ANEG_UNKNOWN) {
+		phylink_dbg(pl,
+			    "PHY driver does not report in-band autoneg capability, assuming %s\n",
+			    phylink_autoneg_inband(mode) ? "true" : "false");
+
+		return mode;
+	}
+
+	if (phylink_autoneg_inband(mode) && !(ret & PHY_INBAND_ANEG_ON)) {
+		phylink_err(pl,
+			    "Requested in-band autoneg but driver does not support this, disabling it.\n");

If we add support to the BCM84881 driver to work with
phy_validate_inband_aneg(), then this will always return
PHY_INBAND_ANEG_OFF and never PHY_INBAND_ANEG_ON. Consequently,
this will always produce this "error". It is not an error in the
SFP case, but it is if firmware is misconfigured.

So, this needs better handling - we should not be issuing an error-
level kernel message for something that is "normal".

Is this better?

		phylink_printk(phy_on_sfp(phy) ? KERN_DEBUG : KERN_ERR, pl,
			       "Requested in-band autoneg but driver does not support this, disabling it.\n");

Ah, not sure whether that was a trick question or not, but
phylink_fixup_inband_aneg function does not get called for the SFP code
path, I even noted this in the commit message but forgot:

No it wasn't a trick question. I thought you were calling
phylink_fixup_inband_aneg() from phylink_sfp_config(), but I see now
that you don't. That's what happens when you try and rush to review.

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