netdev - [PATCH v2 2/2] net: phy: micrel: add toggling phy reset if PHY is not attached

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Date:   Wed, 28 Nov 2018 09:02:42 +0000
From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To:     "andrew@...n.ch" <andrew@...n.ch>,
        "f.fainelli@...il.com" <f.fainelli@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-renesas-soc@...r.kernel.org" 
        <linux-renesas-soc@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
Subject: [PATCH v2 2/2] net: phy: micrel: add toggling phy reset if PHY is not
 attached

This patch adds toggling phy reset if PHY is not attached. Otherwise,
some boards (e.g. R-Car H3 Salvator-XS) cannot link up correctly if
we do the following method:

 1) Kernel boots by using initramfs.
 --> No open the nic, so phy_device_register() and phy_probe()
     deasserts the reset.
 2) Kernel enters the suspend.
 --> So, keep the reset signal as deassert.
 --> On R-Car Salvator-XS board, unfortunately, the board power is
     turned off.
 3) Kernel returns from suspend.
 4) ifconfig eth0 up
 --> Then, since edge signal of the reset doesn't happen,
     it cannot link up.
 5) ifconfig eth0 down
 6) ifconfig eth0 up
 --> In this case, it can link up.

Reported-by: Hiromitsu Yamasaki <hiromitsu.yamasaki.ym@...esas.com>
Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
---
 drivers/net/phy/micrel.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index c333847..fcb561b 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -23,6 +23,7 @@
  *			 ksz9477
  */
 
+#include <linux/delay.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/phy.h>
@@ -840,6 +841,13 @@ static int kszphy_resume(struct phy_device *phydev)
 {
 	int ret;
 
+	if (!phydev->attached_dev) {
+		/* If the PHY is not attached, toggle the reset */
+		phy_device_reset(phydev, 1);
+		udelay(1);
+		phy_device_reset(phydev, 0);
+	}
+
 	genphy_resume(phydev);
 
 	ret = kszphy_config_reset(phydev);
-- 
1.9.1