Re: [PATCH net-next v5] net: phy: Add driver for Motorcomm Quad 2.5GbE phy

On 7/25/26 06:18, Andrew Lunn wrote:

On Fri, Jul 24, 2026 at 03:18:47PM +0200, Andrew Lunn wrote:
1;4000;47c> > Ans: It is different from the m88e1111 PHY, which may support UTP, fiber, 

quoted

quoted

     or combo mode. However, the PHY8824 is only used with UTPs, and 
     its structure is as follows, which includes UTP0, UTP1,UTP2,UTP3 and USXGMII.

     RJ45 <----> UTP0 <------>
     RJ45 <----> UTP1 <------>   USXGMII  <----->  USXGMII(the side of MAC)
     RJ45 <----> UTP2 <------>
     RJ45 <----> UTP3 <------>

     It is similar to phy8821 driver in motorcomm.c, with the difference 
     being that one has one UTP port and phy8824 has four UTP ports.
     YT8824_RSSR_FIBER_SPACE is used to access USXGMII reg space, Perhaps it 
     would be more accurate to call it YT8824_RSSR_USXGMII_SPACE or 
     YT8824_RSSR_SERDES_SPACE.

O.K, that completely changes my understanding of this device. Yes,
YT8824_RSSR_FIBER_SPACE should change name. And i would include this
diagram in the driver, and indicate how YT8824_RSSR_*_SPACE map to
this.

For the locking, look thought all the code which is touching the
USXGMII side and see if it can be moved into probe().

So thinking about locking:

+static int yt8824_config_aneg(struct phy_device *phydev)
+{
+	int phy_ctrl = 0;
+	int ret = 0;
+
+	ret = phy8824_page_write_lock(phydev, YT8824_RSSR_UTP_SPACE);
+	if (ret < 0)
+		return ret;
+
+	if (linkmode_test_bit(ETHTOOL_LINK_MODE_2500baseT_Full_BIT,
+			      phydev->advertising))
+		phy_ctrl = MDIO_AN_10GBT_CTRL_ADV2_5G;
+
+	ret = phy_modify_mmd_changed(phydev, MDIO_MMD_AN,
+				     MDIO_AN_10GBT_CTRL,
+				     MDIO_AN_10GBT_CTRL_ADV2_5G,
+				     phy_ctrl);
+	if (ret)
+		return ret;
+
+	return genphy_config_aneg(phydev);
+

This is only touching the UTP side of things. What a PHY advertises
should not affect the USXGMII side. Why does it need
YT8824_RSSR_UTP_SPACE? What would happen if YT8824_RSSR_USXGMII_SPACE
has selected?

Ans: i have updated PATCH v6 in 
https://patchwork.kernel.org/project/netdevbpf/patch/20260723102112.1155723-1-kyle.switch@motor-comm.com/.
     The log of this patch failure is as "Patch does not apply to net-next-0". 
     The patch v7 will be rebased and updated. Could you provide some comments based on patch v6 included
     refactor the usage of USXGMII, add helper in phy-c45? The definition of YT8824_RSSR_FIBER_SPACE was 
     modified in patch v7.
     
  

    Andrew