From: Vladimir Oltean <vladimir.oltean@nxp.com>
Date: Mon, 6 Jan 2020 03:34:11 +0200
Subject: net: phylink: add support for polling MAC PCS

Git-commit: 1511ed0a0167f523a84b4e727372a5d2ce1b6c2f
Patch-mainline: v5.6-rc1
References: jsc#SLE-9263

Some MAC PCS blocks are unable to provide interrupts when their status
changes. As we already have support in phylink for polling status, use
this to provide a hook for MACs to enable polling mode.

The patch idea was picked up from Russell King's suggestion on the macb
phylink patch thread here [0] but the implementation was changed.
Instead of introducing a new phylink_start_poll() function, which would
make the implementation cumbersome for common PHYLINK implementations
for multiple types of devices, like DSA, just add a boolean property to
the phylink_config structure, which is just as backwards-compatible.

https://lkml.org/lkml/2019/12/16/603

Suggested-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Mian Yousaf Kaukab <yousaf.kaukab@suse.com>
---
 Documentation/networking/sfp-phylink.rst |    3 ++-
 drivers/net/phy/phylink.c                |    3 ++-
 include/linux/phylink.h                  |    2 ++
 3 files changed, 6 insertions(+), 2 deletions(-)

--- a/Documentation/networking/sfp-phylink.rst
+++ b/Documentation/networking/sfp-phylink.rst
@@ -250,7 +250,8 @@ this documentation.
 	phylink_mac_change(priv->phylink, link_is_up);
 
     where ``link_is_up`` is true if the link is currently up or false
-    otherwise.
+    otherwise. If a MAC is unable to provide these interrupts, then
+    it should set ``priv->phylink_config.pcs_poll = true;`` in step 9.
 
 11. Verify that the driver does not call::
 
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1001,7 +1001,8 @@ void phylink_start(struct phylink *pl)
 		if (irq <= 0)
 			mod_timer(&pl->link_poll, jiffies + HZ);
 	}
-	if (pl->link_an_mode == MLO_AN_FIXED && pl->get_fixed_state)
+	if ((pl->link_an_mode == MLO_AN_FIXED && pl->get_fixed_state) ||
+	    pl->config->pcs_poll)
 		mod_timer(&pl->link_poll, jiffies + HZ);
 	if (pl->phydev)
 		phy_start(pl->phydev);
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -63,10 +63,12 @@ enum phylink_op_type {
  * struct phylink_config - PHYLINK configuration structure
  * @dev: a pointer to a struct device associated with the MAC
  * @type: operation type of PHYLINK instance
+ * @pcs_poll: MAC PCS cannot provide link change interrupt
  */
 struct phylink_config {
 	struct device *dev;
 	enum phylink_op_type type;
+	bool pcs_poll;
 };
 
 /**