[PATCH v6 2/6] net: stmmac: sun8i: force select external PHY when no internal one

[megous at megous.com]

From: Icenowy Zheng <icenowy at aosc.io>

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

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,
connected via RMII interface at GPIO bank A).

Force the PHY selection bit to 0 when the SOC doesn't have an internal PHY,
to address the problem of a wrong default value.

Signed-off-by: Icenowy Zheng <icenowy at aosc.io>
Signed-off-by: Ondrej Jirman <megous at megous.com>
---
 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 3258dec84d55..0484c289f328 100644
--- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
+++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c
@@ -907,6 +907,11 @@ 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