net: systemport: Avoid RBUF stuck in Wake-on-LAN mode

BugLink: https://bugs.launchpad.net/bugs/1864775

[ Upstream commit 263a425a ]

After a number of suspend and resume cycles, it is possible for the RBUF
to be stuck in Wake-on-LAN mode, despite the MPD enable bit being
cleared which instructed the RBUF to exit that mode.

Avoid creating that problematic condition by clearing the RX_EN and
TX_EN bits in the UniMAC prior to disable the Magic Packet Detector
logic which is guaranteed to make the RBUF exit Wake-on-LAN mode.

Fixes: 83e82f4c ("net: systemport: add Wake-on-LAN support")
Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/net/ethernet/broadcom/bcmsysport.c

@@ -1997,6 +1997,9 @@ static int bcm_sysport_resume(struct device *d)
 
 	umac_reset(priv);
 
+	/* Disable the UniMAC RX/TX */
+	umac_enable_set(priv, CMD_RX_EN | CMD_TX_EN, 0);
+
 	/* We may have been suspended and never received a WOL event that
 	 * would turn off MPD detection, take care of that now
 	 */