netdev - [PATCH] phy: added a PHY_BUSY state into phy_state

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Date:   Sun,  7 Jul 2019 18:32:12 -0400
From:   "kwangdo.yi" <kwangdo.yi@...il.com>
To:     netdev@...r.kernel.org
Cc:     "kwangdo.yi" <kwangdo.yi@...il.com>
Subject: [PATCH] phy: added a PHY_BUSY state into phy_state_machine

When mdio driver polling the phy state in the phy_state_machine,
sometimes it results in -ETIMEDOUT and link is down. But the phy
is still alive and just didn't meet the polling deadline. 
Closing the phy link in this case seems too radical. Failing to 
meet the deadline happens very rarely. When stress test runs for 
tens of hours with multiple target boards (Xilinx Zynq7000 with
marvell 88E1512 PHY, Xilinx custom emac IP), it happens. This 
patch gives another chance to the phy_state_machine when polling 
timeout happens. Only two consecutive failing the deadline is 
treated as the real phy halt and close the connection.

Signed-off-by: kwangdo.yi <kwangdo.yi@...il.com>
---
 drivers/net/phy/phy.c | 6 ++++++
 include/linux/phy.h   | 1 +
 2 files changed, 7 insertions(+)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index e888542..9e8138b 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -919,7 +919,13 @@ void phy_state_machine(struct work_struct *work)
 		break;
 	case PHY_NOLINK:
 	case PHY_RUNNING:
+	case PHY_BUSY:
 		err = phy_check_link_status(phydev);
+		if (err == -ETIMEDOUT && old_state == PHY_RUNNING) {
+			phy->state = PHY_BUSY;
+			err = 0;
+
+		}
 		break;
 	case PHY_FORCING:
 		err = genphy_update_link(phydev);
diff --git a/include/linux/phy.h b/include/linux/phy.h
index 6424586..4a49401 100644
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -313,6 +313,7 @@ enum phy_state {
 	PHY_RUNNING,
 	PHY_NOLINK,
 	PHY_FORCING,
+	PHY_BUSY,
 };

 /**
-- 
2.7.4