Patch "net: phylink: use a dedicated helper to parse usgmii control word" has been added to the 6.3-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    net: phylink: use a dedicated helper to parse usgmii control word

to the 6.3-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-phylink-use-a-dedicated-helper-to-parse-usgmii-c.patch
and it can be found in the queue-6.3 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 6f7b5f1ca8a2745f2645cefd483f00b0c47b6c14
Author: Maxime Chevallier <maxime.chevallier@xxxxxxxxxxx>
Date:   Fri Jun 9 10:03:05 2023 +0200

    net: phylink: use a dedicated helper to parse usgmii control word
    
    [ Upstream commit 923454c0368b8092e9d05c020f50abca577e7290 ]
    
    Q-USGMII is a derivative of USGMII, that uses a specific formatting for
    the control word. The layout is close to the USXGMII control word, but
    doesn't support speeds over 1Gbps. Use a dedicated decoding logic for
    the USGMII control word, re-using USXGMII definitions but only considering
    10/100/1000Mbps speeds
    
    Fixes: 5e61fe157a27 ("net: phy: Introduce QUSGMII PHY mode")
    Signed-off-by: Maxime Chevallier <maxime.chevallier@xxxxxxxxxxx>
    Reviewed-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx>
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 65ff118f22314..0598debb93dea 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -3297,6 +3297,41 @@ void phylink_decode_usxgmii_word(struct phylink_link_state *state,
 }
 EXPORT_SYMBOL_GPL(phylink_decode_usxgmii_word);
 
+/**
+ * phylink_decode_usgmii_word() - decode the USGMII word from a MAC PCS
+ * @state: a pointer to a struct phylink_link_state.
+ * @lpa: a 16 bit value which stores the USGMII auto-negotiation word
+ *
+ * Helper for MAC PCS supporting the USGMII protocol and the auto-negotiation
+ * code word.  Decode the USGMII code word and populate the corresponding fields
+ * (speed, duplex) into the phylink_link_state structure. The structure for this
+ * word is the same as the USXGMII word, except it only supports speeds up to
+ * 1Gbps.
+ */
+static void phylink_decode_usgmii_word(struct phylink_link_state *state,
+				       uint16_t lpa)
+{
+	switch (lpa & MDIO_USXGMII_SPD_MASK) {
+	case MDIO_USXGMII_10:
+		state->speed = SPEED_10;
+		break;
+	case MDIO_USXGMII_100:
+		state->speed = SPEED_100;
+		break;
+	case MDIO_USXGMII_1000:
+		state->speed = SPEED_1000;
+		break;
+	default:
+		state->link = false;
+		return;
+	}
+
+	if (lpa & MDIO_USXGMII_FULL_DUPLEX)
+		state->duplex = DUPLEX_FULL;
+	else
+		state->duplex = DUPLEX_HALF;
+}
+
 /**
  * phylink_mii_c22_pcs_decode_state() - Decode MAC PCS state from MII registers
  * @state: a pointer to a &struct phylink_link_state.
@@ -3333,9 +3368,11 @@ void phylink_mii_c22_pcs_decode_state(struct phylink_link_state *state,
 
 	case PHY_INTERFACE_MODE_SGMII:
 	case PHY_INTERFACE_MODE_QSGMII:
-	case PHY_INTERFACE_MODE_QUSGMII:
 		phylink_decode_sgmii_word(state, lpa);
 		break;
+	case PHY_INTERFACE_MODE_QUSGMII:
+		phylink_decode_usgmii_word(state, lpa);
+		break;
 
 	default:
 		state->link = false;