Patch "net: phy: micrel: fix KSZ9477 PHY issues after suspend/resume" has been added to the 6.9-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

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

    net: phy: micrel: fix KSZ9477 PHY issues after suspend/resume

to the 6.9-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-phy-micrel-fix-ksz9477-phy-issues-after-suspend-.patch
and it can be found in the queue-6.9 subdirectory.

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



commit 1d3bd7f1d9c86df0dc8515c4c59831b95acf1661
Author: Tristram Ha <tristram.ha@xxxxxxxxxxxxx>
Date:   Tue May 28 19:20:23 2024 -0700

    net: phy: micrel: fix KSZ9477 PHY issues after suspend/resume
    
    [ Upstream commit 6149db4997f582e958da675092f21c666e3b67b7 ]
    
    When the PHY is powered up after powered down most of the registers are
    reset, so the PHY setup code needs to be done again.  In addition the
    interrupt register will need to be setup again so that link status
    indication works again.
    
    Fixes: 26dd2974c5b5 ("net: phy: micrel: Move KSZ9477 errata fixes to PHY driver")
    Signed-off-by: Tristram Ha <tristram.ha@xxxxxxxxxxxxx>
    Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 13370439a7cae..c2d99344ade41 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -1858,7 +1858,7 @@ static const struct ksz9477_errata_write ksz9477_errata_writes[] = {
 	{0x1c, 0x20, 0xeeee},
 };
 
-static int ksz9477_config_init(struct phy_device *phydev)
+static int ksz9477_phy_errata(struct phy_device *phydev)
 {
 	int err;
 	int i;
@@ -1886,16 +1886,30 @@ static int ksz9477_config_init(struct phy_device *phydev)
 			return err;
 	}
 
+	err = genphy_restart_aneg(phydev);
+	if (err)
+		return err;
+
+	return err;
+}
+
+static int ksz9477_config_init(struct phy_device *phydev)
+{
+	int err;
+
+	/* Only KSZ9897 family of switches needs this fix. */
+	if ((phydev->phy_id & 0xf) == 1) {
+		err = ksz9477_phy_errata(phydev);
+		if (err)
+			return err;
+	}
+
 	/* According to KSZ9477 Errata DS80000754C (Module 4) all EEE modes
 	 * in this switch shall be regarded as broken.
 	 */
 	if (phydev->dev_flags & MICREL_NO_EEE)
 		phydev->eee_broken_modes = -1;
 
-	err = genphy_restart_aneg(phydev);
-	if (err)
-		return err;
-
 	return kszphy_config_init(phydev);
 }
 
@@ -2004,6 +2018,42 @@ static int kszphy_resume(struct phy_device *phydev)
 	return 0;
 }
 
+static int ksz9477_resume(struct phy_device *phydev)
+{
+	int ret;
+
+	/* No need to initialize registers if not powered down. */
+	ret = phy_read(phydev, MII_BMCR);
+	if (ret < 0)
+		return ret;
+	if (!(ret & BMCR_PDOWN))
+		return 0;
+
+	genphy_resume(phydev);
+
+	/* After switching from power-down to normal mode, an internal global
+	 * reset is automatically generated. Wait a minimum of 1 ms before
+	 * read/write access to the PHY registers.
+	 */
+	usleep_range(1000, 2000);
+
+	/* Only KSZ9897 family of switches needs this fix. */
+	if ((phydev->phy_id & 0xf) == 1) {
+		ret = ksz9477_phy_errata(phydev);
+		if (ret)
+			return ret;
+	}
+
+	/* Enable PHY Interrupts */
+	if (phy_interrupt_is_valid(phydev)) {
+		phydev->interrupts = PHY_INTERRUPT_ENABLED;
+		if (phydev->drv->config_intr)
+			phydev->drv->config_intr(phydev);
+	}
+
+	return 0;
+}
+
 static int kszphy_probe(struct phy_device *phydev)
 {
 	const struct kszphy_type *type = phydev->drv->driver_data;
@@ -4980,7 +5030,7 @@ static struct phy_driver ksphy_driver[] = {
 	.config_intr	= kszphy_config_intr,
 	.handle_interrupt = kszphy_handle_interrupt,
 	.suspend	= genphy_suspend,
-	.resume		= genphy_resume,
+	.resume		= ksz9477_resume,
 	.get_features	= ksz9477_get_features,
 } };