[PATCH 06/12] net: stmmac: sun8i: force select external PHY when no internal one

[megous@megous.com]

From: Icenowy Zheng <icenowy@aosc.io>

The PHY selection bit also exists on SoCs without an internal PHY; if
it's set to 1 (internal PHY) then the MAC will not make use of any PHY.

This problem appears when adapting for H6, which has no real internal
PHY (the "internal PHY" on H6 is not on-die, but on a co-packaged AC200
chip, via RMII interface at GPIO bank A), but the PHY selection bit is
set.

Force the PHY selection bit to 0 when no external PHY to select this
problem.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
---
 drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
index e3e3dc44b33b..bd340e77b2ea 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
@@ -908,6 +908,11 @@ static int sun8i_dwmac_set_syscon(struct stmmac_priv *priv)
 		 * address. No need to mask it again.
 		 */
 		reg |= 1 << H3_EPHY_ADDR_SHIFT;
+	} else {
+		/* For SoCs without internal PHY the PHY selection bit should be
+		 * set to 0 (external PHY).
+		 */
+		reg &= ~(H3_EPHY_SELECT);
 	}
 
 	if (!of_property_read_u32(node, "allwinner,tx-delay-ps", &val)) {
-- 
2.21.0