It seems reasonable to fine-tune only some of the skew values when using
one of the rgmii-*id PHY modes, and even when all skew values are
specified, using the correct ID PHY mode makes sense for documentation
purposes. Such a configuration also appears in the binding docs in
Documentation/devicetree/bindings/net/micrel-ksz90x1.txt, so the driver
should not warn about it.
Signed-off-by: Matthias Schiffer <matthias.schiffer@ew.tq-group.com>
Link: https://lore.kernel.org/r/20211012103402.21438-1-matthias.schiffer@ew.tq-group.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
                                MII_KSZ9031RN_TX_DATA_PAD_SKEW, 4,
                                tx_data_skews, 4, &update);
 
-               if (update && phydev->interface != PHY_INTERFACE_MODE_RGMII)
+               if (update && !phy_interface_is_rgmii(phydev))
                        phydev_warn(phydev,
-                                   "*-skew-ps values should be used only with phy-mode = \"rgmii\"\n");
+                                   "*-skew-ps values should be used only with RGMII PHY modes\n");
 
                /* Silicon Errata Sheet (DS80000691D or DS80000692D):
                 * When the device links in the 1000BASE-T slave mode only,