[PATCH RFC net-next 8/9] net: stmmac: only call stmmac_pcs_ctrl_ane() for integrated SGMII PCS

The internal PCS registers only exist if the core is synthesized with
SGMII, TBI or RTBI support. They have no relevance for RGMII.

However, priv->hw->pcs contains a STMMAC_PCS_RGMII flag, which is set
if a PCS has been synthesized but we are operating in RGMII mode. As
the register has no effect for RGMII, there is no point calling
stmmac_pcs_ctrl_ane() in this case. Add a comment describing this
and make it conditional on STMMAC_PCS_SGMII.

Signed-off-by: Russell King (Oracle) <redacted>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
index dff3bba83969..fb5a51d16897 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c

@@ -3519,7 +3519,11 @@ static int stmmac_hw_setup(struct net_device *dev)
 		}
 	}
 
-	if (priv->hw->pcs)
+	/* The PCS control register is only relevant for SGMII, TBI and RTBI
+	 * modes. We no longer support TBI or RTBI, so only configure this
+	 * register when operating in SGMII mode with the integrated PCS.
+	 */
+	if (priv->hw->pcs & STMMAC_PCS_SGMII)
 		stmmac_pcs_ctrl_ane(priv, 1, priv->hw->reverse_sgmii_enable);
 
 	/* set TX and RX rings length */

-- 
2.47.3