[PATCH 3/3] net: phy: dp83867: sync dp83867_phy_rest

[Stefan Kerkmann <s.kerkmann@pengutronix.de>]

This is a port of the `dp83867_phy_reset` function at the state of linux
commit a129b41fe0a8b4da828c46b10f5244ca07a3fec3 ("Revert "net: phy:
dp83867: perform soft reset and retain established link"). Which
performs a reset before starting the initial configuration.

It is a refactoring of commit 095cd32961aab64cfe72941ce43d99876852e12b
("net: phy: dp83867: reset PHY on probe") which already ported parts of
the function, but diverted from the upstream implementation.

Signed-off-by: Stefan Kerkmann <s.kerkmann@pengutronix.de>
---
 drivers/net/phy/dp83867.c | 28 ++++++++++++++++++++++------
 1 file changed, 22 insertions(+), 6 deletions(-)

diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
index aefc651489..3c9a8e6355 100644
--- a/drivers/net/phy/dp83867.c
+++ b/drivers/net/phy/dp83867.c
@@ -362,8 +362,6 @@ static int dp83867_of_init(struct phy_device *phydev)
 	return 0;
 }
 
-static int dp83867_phy_reset(struct phy_device *phydev); /* see below */
-
 static int dp83867_probe(struct phy_device *phydev)
 {
 	struct dp83867_private *dp83867;
@@ -372,8 +370,6 @@ static int dp83867_probe(struct phy_device *phydev)
 
 	phydev->priv = dp83867;
 
-	dp83867_phy_reset(phydev);
-
 	return dp83867_of_init(phydev);
 }
 
@@ -571,14 +567,33 @@ static int dp83867_phy_reset(struct phy_device *phydev)
 {
 	int err;
 
+	err = phy_write(phydev, DP83867_CTRL, DP83867_SW_RESET);
+	if (err < 0)
+		return err;
+
+	udelay(20);
+
+	err = phy_modify(phydev, MII_DP83867_PHYCTRL,
+			 DP83867_PHYCR_FORCE_LINK_GOOD, 0);
+	if (err < 0)
+		return err;
+
+	/* Configure the DSP Feedforward Equalizer Configuration register to
+	 * improve short cable (< 1 meter) performance. This will not affect
+	 * long cable performance.
+	 */
+	err = phy_write_mmd(phydev, DP83867_DEVADDR, DP83867_DSP_FFE_CFG,
+			    0x0e81);
+	if (err < 0)
+		return err;
+
 	err = phy_write(phydev, DP83867_CTRL, DP83867_SW_RESTART);
 	if (err < 0)
 		return err;
 
 	udelay(20);
 
-	return phy_modify(phydev, MII_DP83867_PHYCTRL,
-			 DP83867_PHYCR_FORCE_LINK_GOOD, 0);
+	return 0;
 }
 
 static struct phy_driver dp83867_driver[] = {
@@ -590,6 +605,7 @@ static struct phy_driver dp83867_driver[] = {
 
 		.probe          = dp83867_probe,
 		.config_init	= dp83867_config_init,
+		.soft_reset	= dp83867_phy_reset,
 
 		.read_status	= dp83867_read_status,
 	},

-- 
2.39.2