linux-kernel - [PATCH 4.9 028/105] net: phy: Do not perform software reset for Generic PHY

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Date:   Fri,  4 Aug 2017 16:14:56 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Felix Fietkau <nbd@....name>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Amit Pundir <amit.pundir@...aro.org>
Subject: [PATCH 4.9 028/105] net: phy: Do not perform software reset for Generic PHY

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Florian Fainelli <f.fainelli@...il.com>

commit 0878fff1f42c18e448ab5b8b4f6a3eb32365b5b6 upstream.

The Generic PHY driver is a catch-all PHY driver and it should preserve
whatever prior initialization has been done by boot loader or firmware
agents. For specific PHY device configuration it is expected that a
specialized PHY driver would take over that role.

Resetting the generic PHY was a bad idea that has lead to several
complaints and downstream workarounds e.g: in OpenWrt/LEDE so restore
the behavior prior to 87aa9f9c61ad ("net: phy: consolidate PHY
reset in phy_init_hw()").

Reported-by: Felix Fietkau <nbd@....name>
Fixes: 87aa9f9c61ad ("net: phy: consolidate PHY reset in phy_init_hw()")
Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Amit Pundir <amit.pundir@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/net/phy/phy_device.c |    2 +-
 include/linux/phy.h          |    4 ++++
 2 files changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -1792,7 +1792,7 @@ static struct phy_driver genphy_driver[]
 	.phy_id		= 0xffffffff,
 	.phy_id_mask	= 0xffffffff,
 	.name		= "Generic PHY",
-	.soft_reset	= genphy_soft_reset,
+	.soft_reset	= genphy_no_soft_reset,
 	.config_init	= genphy_config_init,
 	.features	= PHY_GBIT_FEATURES | SUPPORTED_MII |
 			  SUPPORTED_AUI | SUPPORTED_FIBRE |
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -799,6 +799,10 @@ int genphy_read_status(struct phy_device
 int genphy_suspend(struct phy_device *phydev);
 int genphy_resume(struct phy_device *phydev);
 int genphy_soft_reset(struct phy_device *phydev);
+static inline int genphy_no_soft_reset(struct phy_device *phydev)
+{
+	return 0;
+}
 void phy_driver_unregister(struct phy_driver *drv);
 void phy_drivers_unregister(struct phy_driver *drv, int n);
 int phy_driver_register(struct phy_driver *new_driver, struct module *owner);