arch/risc-v/src/mpfs/mpfs_ethernet.c: Add RX timeout workaround for broken PHYs

If the interface is UP, and no packets are received in 30s, re-initialize the interface by calling the
already implemented mpfs_txtimeout_expiry.

This is a workaround for a bug where IF might be UP and working but packets can only
be transmitted. Receive side just doesn't work at all. The bug manifests at least in
older LAN8742A (rev A and B), for which also a silicon errata exists.

The original issue can be re-produced easily by disconnecting and reconnecting the ethernet cable while
the IF is up.

Signed-off-by: Jukka Laitinen <[email protected]>

Author: jlaitine

arch/risc-v/src/mpfs/Kconfig

@@ -833,6 +833,14 @@ config MPFS_PHYINIT
 	---help---
 		call mpfs_phy_boardinitialize() on init
 
+config MPFS_PHY_RX_TIMEOUT_WA
+	int "RX restart timeout workaround"
+	default 0
+	---help---
+		This is a workaround for LAN8742A rev A and B silicon errata.
+		Reset ETH interface in case no RX packets have been received
+		in configured time. Set to 0 to disable.
+
 config MPFS_ETH0_PHY_KSZ9477
 	bool "Use ksz9477 switch as an SGMII PHY for ETH0"
 	default n

arch/risc-v/src/mpfs/mpfs_ethernet.c

@@ -168,6 +168,15 @@
 
 #define MPFS_TXTIMEOUT   (60 * CLK_TCK)
 
+/* RX timeout: Workaround for LAN8742A rev A and B silicon errata
+ * "Cable diagnostics incorrectly returns Open cable connection for
+ *  terminated cable"
+ */
+
+#if CONFIG_MPFS_PHY_RX_TIMEOUT_WA != 0
+#define MPFS_RXTIMEOUT   (CONFIG_MPFS_PHY_RX_TIMEOUT_WA * CLK_TCK)
+#endif
+
 /* PHY reset tim in loop counts */
 
 #define PHY_RESET_WAIT_COUNT (10)
@@ -265,6 +274,9 @@ struct mpfs_ethmac_s
   uint8_t       phyaddr;                         /* PHY address */
 #endif
   struct wdog_s txtimeout;                       /* TX timeout timer */
+#ifdef MPFS_RXTIMEOUT
+  struct wdog_s rxtimeout;                       /* RX timeout timer */
+#endif
   struct work_s irqwork;                         /* For deferring interrupt work to the work queue */
   struct work_s pollwork;                        /* For deferring poll work to the work queue */
   struct work_s timeoutwork;                     /* For managing timeouts */
@@ -387,6 +399,7 @@ static int  mpfs_ethconfig(struct mpfs_ethmac_s *priv);
 static void mpfs_ethreset(struct mpfs_ethmac_s *priv);
 
 static void mpfs_interrupt_work(void *arg);
+static void mpfs_txtimeout_expiry(wdparm_t arg);
 
 /****************************************************************************
  * Private Functions
@@ -468,6 +481,16 @@ static int mpfs_interrupt_0(int irq, void *context, void *arg)
       wd_cancel(&priv->txtimeout);
     }
 
+#ifdef MPFS_RXTIMEOUT
+  if ((isr & INT_RX) != 0)
+    {
+      /* If a RX transfer just completed, restart the timeout */
+
+      wd_start(&priv->rxtimeout, MPFS_RXTIMEOUT,
+               mpfs_txtimeout_expiry, (wdparm_t)priv);
+    }
+#endif
+
   /* Schedule to perform the interrupt processing on the worker thread. */
 
   work_queue(ETHWORK, &priv->irqwork, mpfs_interrupt_work, priv, 0);
@@ -1556,6 +1579,15 @@ static int mpfs_ifup(struct net_driver_s *dev)
   up_enable_irq(priv->mac_q_int[2]);
   up_enable_irq(priv->mac_q_int[3]);
 
+#ifdef MPFS_RXTIMEOUT
+  /* Set up the RX timeout. If we don't receive anything in time, try
+   * to re-initialize
+   */
+
+  wd_start(&priv->rxtimeout, MPFS_RXTIMEOUT,
+           mpfs_txtimeout_expiry, (wdparm_t)priv);
+#endif
+
   return OK;
 }
 
@@ -1599,6 +1631,12 @@ static int mpfs_ifdown(struct net_driver_s *dev)
 
   wd_cancel(&priv->txtimeout);
 
+#ifdef MPFS_RXTIMEOUT
+  /* Cancel the RX timeout timers */
+
+  wd_cancel(&priv->rxtimeout);
+#endif
+
   /* Put the MAC in its reset, non-operational state.  This should be
    * a known configuration that will guarantee the mpfs_ifup() always
    * successfully brings the interface back up.