[PATCH 1/2] net: phylink: add a function to resume phy alone to fix resume issue with WoL enabled

Clark Wang
2022-12-21T08:03:04Z

Issue we met:
On some platforms, mac cannot work after resumed from the suspend with WoL
enabled.

The cause of the issue:
1. phylink_resolve() is in a workqueue which will not be executed immediately.
This is the call sequence:
phylink_resolve()->phylink_link_up()->pl->mac_ops->mac_link_up()
For stmmac driver, mac_link_up() will set the correct speed/duplex...
values which are from link_state.
2. In stmmac_resume(), it will call stmmac_hw_setup() after called the
phylink_resume(), because mac need phy rx_clk to do the reset.
stmmac_core_init() is called in function stmmac_hw_setup(), which will
reset the mac and set the speed/duplex... to default value.
Conclusion: Because phylink_resolve() cannot determine when it is called, it
cannot be guaranteed to be called after stmmac_core_init().
Once stmmac_core_init() is called after phylink_resolve(),
the mac will be misconfigured and cannot be used.

In order to avoid this problem, add a function called phylink_phy_resume()
to resume phy separately. This eliminates the need to call phylink_resume()
before stmmac_hw_setup().

Add another judgement before called phy_start() in phylink_start(). This way
phy_start() will not be called multiple times when resumes. At the same time,
it may not affect other drivers that do not use phylink_phy_resume().

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
---
drivers/net/phy/phylink.c | 21 ++++++++++++++++++++-
include/linux/phylink.h | 1 +
2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/net/phy/phylink.c b/drivers/net/phy/phylink.c
index 09cc65c0da93..5bab59142579 100644
--- a/drivers/net/phy/phylink.c
+++ b/drivers/net/phy/phylink.c
@@ -1939,7 +1939,7 @@ void phylink_start(struct phylink *pl)
}
if (poll)
mod_timer(&pl->link_poll, jiffies + HZ);
- if (pl->phydev)
+ if (pl->phydev && pl->phydev->state < PHY_UP)
phy_start(pl->phydev);
if (pl->sfp_bus)
sfp_upstream_start(pl->sfp_bus);
@@ -2020,6 +2020,25 @@ void phylink_suspend(struct phylink *pl, bool mac_wol)
}
EXPORT_SYMBOL_GPL(phylink_suspend);

+/**
+ * phylink_phy_resume() - resume phy alone
+ * @pl: a pointer to a &struct phylink returned from phylink_create()
+ *
+ * In the MAC driver using phylink, if the MAC needs the clock of the phy
+ * when it resumes, can call this function to resume the phy separately.
+ * Then proceed to MAC resume operations.
+ */
+void phylink_phy_resume(struct phylink *pl)
+{
+ ASSERT_RTNL();
+
+ if (!test_bit(PHYLINK_DISABLE_MAC_WOL, &pl->phylink_disable_state)
+ && pl->phydev)
+ phy_start(pl->phydev);
+
+}
+EXPORT_SYMBOL_GPL(phylink_phy_resume);
+
/**
* phylink_resume() - handle a network device resume event
* @pl: a pointer to a &struct phylink returned from phylink_create()
diff --git a/include/linux/phylink.h b/include/linux/phylink.h
index c492c26202b5..6edfab5f754c 100644
--- a/include/linux/phylink.h
+++ b/include/linux/phylink.h
@@ -589,6 +589,7 @@ void phylink_stop(struct phylink *);

void phylink_suspend(struct phylink *pl, bool mac_wol);
void phylink_resume(struct phylink *pl);
+void phylink_phy_resume(struct phylink *pl);

void phylink_ethtool_get_wol(struct phylink *, struct ethtool_wolinfo *);
int phylink_ethtool_set_wol(struct phylink *, struct ethtool_wolinfo *);
--
2.34.1