[PATCH v2 net] net: phy: meson-gxl: use MMD access dummy stubs for GXL, internal PHY

[Heiner Kallweit]

Jerome provided the information that also the GXL internal PHY doesn't
support MMD register access and EEE. MMD reads return 0xffff, what
results in e.g. completely wrong ethtool --show-eee output.
Therefore use the MMD dummy stubs.

v2:
- Change Fixes tag to the actually offending commit. As 4.9 is EOL
  this fix will apply on all stable versions.

Fixes: d853d145ea3e ("net: phy: add an option to disable EEE advertisement")
Suggested-by: Jerome Brunet <jbrunet at baylibre.com>
Signed-off-by: Heiner Kallweit <hkallweit1 at gmail.com>
---
 drivers/net/phy/meson-gxl.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/phy/meson-gxl.c b/drivers/net/phy/meson-gxl.c
index c49062ad7..fbf5f2416 100644
--- a/drivers/net/phy/meson-gxl.c
+++ b/drivers/net/phy/meson-gxl.c
@@ -261,6 +261,8 @@ static struct phy_driver meson_gxl_phy[] = {
 		.handle_interrupt = meson_gxl_handle_interrupt,
 		.suspend        = genphy_suspend,
 		.resume         = genphy_resume,
+		.read_mmd	= genphy_read_mmd_unsupported,
+		.write_mmd	= genphy_write_mmd_unsupported,
 	}, {
 		PHY_ID_MATCH_EXACT(0x01803301),
 		.name		= "Meson G12A Internal PHY",
-- 
2.39.1