[PATCH 3.18 32/46] net: stmmac: enable EEE in MII, GMII or RGMII only

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jerome Brunet <jbrunet@baylibre.com>


[ Upstream commit 879626e3a52630316d817cbda7cec9a5446d1d82 ]

Note in the databook - Section 4.4 - EEE :
" The EEE feature is not supported when the MAC is configured to use the
TBI, RTBI, SMII, RMII or SGMII single PHY interface. Even if the MAC
supports multiple PHY interfaces, you should activate the EEE mode only
when the MAC is operating with GMII, MII, or RGMII interface."

Applying this restriction solves a stability issue observed on Amlogic
gxl platforms operating with RMII interface and the internal PHY.

Fixes: 83bf79b6bb64 ("stmmac: disable at run-time the EEE if not supported")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Tested-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c |    6 ++++++
 include/linux/phy.h                               |   11 +++++++++++
 2 files changed, 17 insertions(+)

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -277,8 +277,14 @@ bool stmmac_eee_init(struct stmmac_priv
 {
 	char *phy_bus_name = priv->plat->phy_bus_name;
 	unsigned long flags;
+	int interface = priv->plat->interface;
 	bool ret = false;
 
+	if ((interface != PHY_INTERFACE_MODE_MII) &&
+	    (interface != PHY_INTERFACE_MODE_GMII) &&
+	    !phy_interface_mode_is_rgmii(interface))
+		goto out;
+
 	/* Using PCS we cannot dial with the phy registers at this stage
 	 * so we do not support extra feature like EEE.
 	 */
--- a/include/linux/phy.h
+++ b/include/linux/phy.h
@@ -678,6 +678,17 @@ static inline int phy_write_mmd(struct p
 }
 
 /**
+ * phy_interface_mode_is_rgmii - Convenience function for testing if a
+ * PHY interface mode is RGMII (all variants)
+ * @mode: the phy_interface_t enum
+ */
+static inline bool phy_interface_mode_is_rgmii(phy_interface_t mode)
+{
+	return mode >= PHY_INTERFACE_MODE_RGMII &&
+		mode <= PHY_INTERFACE_MODE_RGMII_TXID;
+};
+
+/**
  * phy_write_mmd_indirect - writes data to the MMD registers
  * @phydev: The PHY device
  * @prtad: MMD Address