linux-kernel - [PATCH 4.19 36/89] net: phy: fix MDIO bus PM PHY resuming

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Message-Id: <20200317103304.148695975@linuxfoundation.org>
Date:   Tue, 17 Mar 2020 11:54:45 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Geert Uytterhoeven <geert@...ux-m68k.org>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.19 36/89] net: phy: fix MDIO bus PM PHY resuming

From: Heiner Kallweit <hkallweit1@...il.com>

[ Upstream commit 611d779af7cad2b87487ff58e4931a90c20b113c ]

So far we have the unfortunate situation that mdio_bus_phy_may_suspend()
is called in suspend AND resume path, assuming that function result is
the same. After the original change this is no longer the case,
resulting in broken resume as reported by Geert.

To fix this call mdio_bus_phy_may_suspend() in the suspend path only,
and let the phy_device store the info whether it was suspended by
MDIO bus PM.

Fixes: 503ba7c69610 ("net: phy: Avoid multiple suspends")
Reported-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Tested-by: Geert Uytterhoeven <geert@...ux-m68k.org>
Signed-off-by: Heiner Kallweit <hkallweit1@...il.com>
Reviewed-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/net/phy/phy_device.c |    6 +++++-
 include/linux/phy.h          |    2 ++
 2 files changed, 7 insertions(+), 1 deletion(-)

--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -130,6 +130,8 @@ static int mdio_bus_phy_suspend(struct d
 	if (!mdio_bus_phy_may_suspend(phydev))
 		return 0;
 
+	phydev->suspended_by_mdio_bus = 1;
+
 	return phy_suspend(phydev);
 }
 
@@ -138,9 +140,11 @@ static int mdio_bus_phy_resume(struct de
 	struct phy_device *phydev = to_phy_device(dev);
 	int ret;
 
-	if (!mdio_bus_phy_may_suspend(phydev))
+	if (!phydev->suspended_by_mdio_bus)
 		goto no_resume;
 
+	phydev->suspended_by_mdio_bus = 0;
+
 	ret = phy_resume(phydev);
 	if (ret < 0)
 		return ret;
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -373,6 +373,7 @@ struct phy_c45_device_ids {
  * is_pseudo_fixed_link: Set to true if this phy is an Ethernet switch, etc.
  * has_fixups: Set to true if this phy has fixups/quirks.
  * suspended: Set to true if this phy has been suspended successfully.
+ * suspended_by_mdio_bus: Set to true if this phy was suspended by MDIO bus.
  * sysfs_links: Internal boolean tracking sysfs symbolic links setup/removal.
  * loopback_enabled: Set true if this phy has been loopbacked successfully.
  * state: state of the PHY for management purposes
@@ -411,6 +412,7 @@ struct phy_device {
 	unsigned is_pseudo_fixed_link:1;
 	unsigned has_fixups:1;
 	unsigned suspended:1;
+	unsigned suspended_by_mdio_bus:1;
 	unsigned sysfs_links:1;
 	unsigned loopback_enabled:1;