linux-kernel - [PATCH net-next v1 4/4] net: usb: asix: suspend internal PHY if external is used

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Date:   Thu, 10 Mar 2022 12:44:34 +0100
From:   Oleksij Rempel <o.rempel@...gutronix.de>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, Andrew Lunn <andrew@...n.ch>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>
Cc:     Oleksij Rempel <o.rempel@...gutronix.de>, kernel@...gutronix.de,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        netdev@...r.kernel.org, paskripkin@...il.com
Subject: [PATCH net-next v1 4/4] net: usb: asix: suspend internal PHY if external is used

In case external PHY is used, we need to take care of internal PHY.
Since there are no methods to disable this PHY from the MAC side, we
need to suspend it.
This we reduce electrical noise (PHY is continuing to send FLPs) and power
consumption by 0,22W.

Signed-off-by: Oleksij Rempel <o.rempel@...gutronix.de>
---
 drivers/net/usb/asix.h         |  3 +++
 drivers/net/usb/asix_devices.c | 16 +++++++++++++++-
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/asix.h b/drivers/net/usb/asix.h
index 072760d76a72..8a087205355d 100644
--- a/drivers/net/usb/asix.h
+++ b/drivers/net/usb/asix.h
@@ -158,6 +158,8 @@
 #define AX_EEPROM_MAGIC		0xdeadbeef
 #define AX_EEPROM_LEN		0x200
 
+#define AX_INTERNAL_PHY_ADDR	0x10
+
 /* This structure cannot exceed sizeof(unsigned long [5]) AKA 20 bytes */
 struct asix_data {
 	u8 multi_filter[AX_MCAST_FILTER_SIZE];
@@ -183,6 +185,7 @@ struct asix_common_private {
 	struct asix_rx_fixup_info rx_fixup_info;
 	struct mii_bus *mdio;
 	struct phy_device *phydev;
+	struct phy_device *phydev_int;
 	u16 phy_addr;
 	bool embd_phy;
 	u8 chipcode;
diff --git a/drivers/net/usb/asix_devices.c b/drivers/net/usb/asix_devices.c
index fb617eb551bb..2c63fbe32ca2 100644
--- a/drivers/net/usb/asix_devices.c
+++ b/drivers/net/usb/asix_devices.c
@@ -679,6 +679,20 @@ static int ax88772_init_phy(struct usbnet *dev)
 
 	phy_attached_info(priv->phydev);
 
+	if (priv->embd_phy)
+		return 0;
+
+	/* In case main PHY is not the embedded PHY, we need to take care of
+	 * embedded PHY as well. */
+	priv->phydev_int = mdiobus_get_phy(priv->mdio, AX_INTERNAL_PHY_ADDR);
+	if (!priv->phydev_int) {
+		netdev_err(dev->net, "Could not find internal PHY\n");
+		return -ENODEV;
+	}
+
+	priv->phydev_int->mac_managed_pm = 1;
+	phy_suspend(priv->phydev_int);
+
 	return 0;
 }
 
@@ -734,7 +748,7 @@ static int ax88772_bind(struct usbnet *dev, struct usb_interface *intf)
 		return ret;
 
 	priv->phy_addr = ret;
-	priv->embd_phy = ((priv->phy_addr & 0x1f) == 0x10);
+	priv->embd_phy = ((priv->phy_addr & 0x1f) == AX_INTERNAL_PHY_ADDR);
 
 	ret = asix_read_cmd(dev, AX_CMD_STATMNGSTS_REG, 0, 0, 1,
 			    &priv->chipcode, 0);
-- 
2.30.2