netdev - [PATCH 2/2] net: macb: fix connectivity after resume

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Date:   Mon, 5 Dec 2022 17:33:28 +0200
From:   Claudiu Beznea <claudiu.beznea@...rochip.com>
To:     <nicolas.ferre@...rochip.com>, <davem@...emloft.net>,
        <edumazet@...gle.com>, <kuba@...nel.org>, <pabeni@...hat.com>,
        <linux@...linux.org.uk>, <andrew@...n.ch>, <hkallweit1@...il.com>
CC:     <sergiu.moga@...rochip.com>, <netdev@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>
Subject: [PATCH 2/2] net: macb: fix connectivity after resume

Commit bf0ad1893442 ("net: macb: Specify PHY PM management done by MAC")
signals to PHY layer that the PHY PM management is done by the MAC driver
itself. In case this is done the mdio_bus_phy_suspend() and
mdio_bus_phy_resume() will return just at its beginning letting the MAC
driver to handle the PHY power management.

AT91 devices (e.g. SAMA7G5, SAMA5D2) has a special power saving mode
called backup and self-refresh where most of the SoCs parts are shutdown
on suspend and RAM is switched to self-refresh. The rail powering the
on-board ethernet PHY could also be closed.

For scenarios where backup and self-refresh is used the MACB driver needs
to re-initialize the PHY device itself when resuming. Otherwise there is
poor or missing connectivity (e.g. SAMA7G5-EK uses KSZ9131 in RGMII mode
which needs its DLL settings to satisfy RGMII timings). For this
phylink_init_phydev() has been called on resume path before
phylink_start(). Up to
commit bf0ad1893442 ("net: macb: Specify PHY PM management done by MAC")
this has been handled by mdio_bus_phy_resume().

This has been tested on SAMA7G5-EK (with KSZ9131 and KSZ8081 PHYs), on
SAMA5D2 (with KSZ8081 PHY), on SAM9X60 (with KSZ8081 PHY).

Fixes: bf0ad1893442 ("net: macb: Specify PHY PM management done by MAC")
Signed-off-by: Claudiu Beznea <claudiu.beznea@...rochip.com>
---

This patch depends on patch 1/2 from this series. For proper backporting
to older kernel (in case this series is integrated as is) please add the
Depends-on tag on this patch after patch 1/2 is integrated in networking
tree.

Thank you,
Claudiu Beznea

 drivers/net/ethernet/cadence/macb_main.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 95667b979fab..8baa53706721 100644
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -5238,6 +5238,7 @@ static int __maybe_unused macb_resume(struct device *dev)
 	if (!device_may_wakeup(&bp->dev->dev))
 		phy_init(bp->sgmii_phy);

+	phylink_init_phydev(bp->phylink);
 	phylink_start(bp->phylink);
 	rtnl_unlock();

-- 
2.34.1