[PATCH 4.16 065/272] dp83640: Ensure against premature access to PHY registers after reset

Greg Kroah-Hartman
2018-05-28T11:06:54Z

From: Esben Haabendal <eha@deif.com>

[ Upstream commit 76327a35caabd1a932e83d6a42b967aa08584e5d ]

The datasheet specifies a 3uS pause after performing a software
reset. The default implementation of genphy_soft_reset() does not
provide this, so implement soft_reset with the needed pause.

Signed-off-by: Esben Haabendal <eha@deif.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/phy/dp83640.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)

--- a/drivers/net/phy/dp83640.c
+++ b/drivers/net/phy/dp83640.c
@@ -1207,6 +1207,23 @@ static void dp83640_remove(struct phy_de
kfree(dp83640);
}

+static int dp83640_soft_reset(struct phy_device *phydev)
+{
+ int ret;
+
+ ret = genphy_soft_reset(phydev);
+ if (ret < 0)
+ return ret;
+
+ /* From DP83640 datasheet: "Software driver code must wait 3 us
+ * following a software reset before allowing further serial MII
+ * operations with the DP83640."
+ */
+ udelay(10); /* Taking udelay inaccuracy into account */
+
+ return 0;
+}
+
static int dp83640_config_init(struct phy_device *phydev)
{
struct dp83640_private *dp83640 = phydev->priv;
@@ -1501,6 +1518,7 @@ static struct phy_driver dp83640_driver
.flags = PHY_HAS_INTERRUPT,
.probe = dp83640_probe,
.remove = dp83640_remove,
+ .soft_reset = dp83640_soft_reset,
.config_init = dp83640_config_init,
.ack_interrupt = dp83640_ack_interrupt,
.config_intr = dp83640_config_intr,