[PATCH 1/2] net: ti: am65-cpsw-nuss: Workaround for buggy PHY/Board

[Roger Quadros]

Beagleplay has a buggy Ethernet PHY implementation for the Gigabit
PHY in the sense that it is non responsive over MDIO immediately
after power-up/reset.

We need to either try multiple times or wait sufficiently long enough
(couple of 10s of ms?) before the PHY begins to respond correctly.

One theory is that the PHY is configured to operate on MDIO address 0
which it treats as a special broadcast address.

Datasheet states:
"PHYAD (config pins) sets the PHY address for the device.
The RTL8211F(I)/RTL8211FD(I) supports PHY addresses from 0x01 to 0x07.
Note 1: An MDIO command with PHY address=0 is a broadcast from the MAC;
each PHY device should respond."

This issue is not seen with the other PHY (different make) on the board
which is configured for address 0x1.

As a woraround we try to probe the PHY multiple times instead of giving
up on the first attempt.

Signed-off-by: Roger Quadros <rogerq at kernel.org>
---
 drivers/net/ti/am65-cpsw-nuss.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/net/ti/am65-cpsw-nuss.c b/drivers/net/ti/am65-cpsw-nuss.c
index 51a8167d14..4f8a2f9b93 100644
--- a/drivers/net/ti/am65-cpsw-nuss.c
+++ b/drivers/net/ti/am65-cpsw-nuss.c
@@ -27,6 +27,7 @@
 #include <syscon.h>
 #include <linux/bitops.h>
 #include <linux/soc/ti/ti-udma.h>
+#include <linux/delay.h>
 
 #include "cpsw_mdio.h"
 
@@ -678,14 +679,22 @@ static int am65_cpsw_phy_init(struct udevice *dev)
 	struct am65_cpsw_priv *priv = dev_get_priv(dev);
 	struct am65_cpsw_common *cpsw_common = priv->cpsw_common;
 	struct eth_pdata *pdata = dev_get_plat(dev);
-	struct phy_device *phydev;
 	u32 supported = PHY_GBIT_FEATURES;
+	struct phy_device *phydev;
+	int tries;
 	int ret;
 
-	phydev = phy_connect(cpsw_common->bus,
-			     priv->phy_addr,
-			     priv->dev,
-			     pdata->phy_interface);
+	/* Some boards (e.g. beagleplay) don't work on first go */
+	for (tries = 1; tries <= 5; tries++) {
+		phydev = phy_connect(cpsw_common->bus,
+				     priv->phy_addr,
+				     priv->dev,
+				     pdata->phy_interface);
+		if (phydev)
+			break;
+
+		mdelay(10);
+	}
 
 	if (!phydev) {
 		dev_err(dev, "phy_connect() failed\n");
-- 
2.34.1