[U-Boot] [PATCH] drivers: net: phy: Ignore PHY ID 0 during PHY probing

[Alexandru Marginean]

Current code fails to probe some C45 PHYs that also respond to C22 reads.
This is the case for PHYs like Aquantia AQR112, Marvell 88X2242 (as
previously posted on the u-boot list).
If the PHY ID reads all 0s just ignore it and try the next devad.

Signed-off-by: Alex Marginean <alexm.osslist at gmail.com>
---
 drivers/net/phy/phy.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index c1c1af9abd..7ccbc4d9da 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -727,6 +727,15 @@ static struct phy_device *create_phy_by_mask(struct mii_dev *bus,
 	while (phy_mask) {
 		int addr = ffs(phy_mask) - 1;
 		int r = get_phy_id(bus, addr, devad, &phy_id);
+
+		/* If the PHY ID is flat 0 we ignore it.  There are C45 PHYs
+		 * that return all 0s for C22 reads (like Aquantia AQR112) and
+		 * there are C22 PHYs that return all 0s for C45 reads (like
+		 * Atheros AR8035).
+		 */
+		if (phy_id == 0)
+			return NULL;
+
 		/* If the PHY ID is mostly f's, we didn't find anything */
 		if (r == 0 && (phy_id & 0x1fffffff) != 0x1fffffff) {
 			is_c45 = (devad == MDIO_DEVAD_NONE) ? false : true;
-- 
2.17.1