6 files changed, 62 insertions, 5 deletions
diff --git a/drivers/net/ethernet/qualcomm/Makefile b/drivers/net/ethernet/qualcomm/Makefile
index 1847350f48a7..9250976dd884 100644
--- a/drivers/net/ethernet/qualcomm/Makefile
+++ b/drivers/net/ethernet/qualcomm/Makefile
@@ -1,3 +1,4 @@
+# SPDX-License-Identifier: GPL-2.0
 #
 # Makefile for the Qualcomm network device drivers.
 #
diff --git a/drivers/net/ethernet/qualcomm/emac/emac-ethtool.c b/drivers/net/ethernet/qualcomm/emac/emac-ethtool.c
index bbe24639aa5a..c8c6231b87f3 100644
--- a/drivers/net/ethernet/qualcomm/emac/emac-ethtool.c
+++ b/drivers/net/ethernet/qualcomm/emac/emac-ethtool.c
@@ -88,6 +88,8 @@ static void emac_set_msglevel(struct net_device *netdev, u32 data)
 static int emac_get_sset_count(struct net_device *netdev, int sset)
 {
 	switch (sset) {
+	case ETH_SS_PRIV_FLAGS:
+		return 1;
 	case ETH_SS_STATS:
 		return EMAC_STATS_LEN;
 	default:
@@ -100,6 +102,10 @@ static void emac_get_strings(struct net_device *netdev, u32 stringset, u8 *data)
 	unsigned int i;
 
 	switch (stringset) {
+	case ETH_SS_PRIV_FLAGS:
+		strcpy(data, "single-pause-mode");
+		break;
+
 	case ETH_SS_STATS:
 		for (i = 0; i < EMAC_STATS_LEN; i++) {
 			strlcpy(data, emac_ethtool_stat_strings[i],
@@ -230,6 +236,27 @@ static int emac_get_regs_len(struct net_device *netdev)
 	return EMAC_MAX_REG_SIZE * sizeof(u32);
 }
 
+#define EMAC_PRIV_ENABLE_SINGLE_PAUSE	BIT(0)
+
+static int emac_set_priv_flags(struct net_device *netdev, u32 flags)
+{
+	struct emac_adapter *adpt = netdev_priv(netdev);
+
+	adpt->single_pause_mode = !!(flags & EMAC_PRIV_ENABLE_SINGLE_PAUSE);
+
+	if (netif_running(netdev))
+		return emac_reinit_locked(adpt);
+
+	return 0;
+}
+
+static u32 emac_get_priv_flags(struct net_device *netdev)
+{
+	struct emac_adapter *adpt = netdev_priv(netdev);
+
+	return adpt->single_pause_mode ? EMAC_PRIV_ENABLE_SINGLE_PAUSE : 0;
+}
+
 static const struct ethtool_ops emac_ethtool_ops = {
 	.get_link_ksettings = phy_ethtool_get_link_ksettings,
 	.set_link_ksettings = phy_ethtool_set_link_ksettings,
@@ -253,6 +280,9 @@ static const struct ethtool_ops emac_ethtool_ops = {
 
 	.get_regs_len    = emac_get_regs_len,
 	.get_regs        = emac_get_regs,
+
+	.set_priv_flags = emac_set_priv_flags,
+	.get_priv_flags = emac_get_priv_flags,
 };
 
 void emac_set_ethtool_ops(struct net_device *netdev)
diff --git a/drivers/net/ethernet/qualcomm/emac/emac-mac.c b/drivers/net/ethernet/qualcomm/emac/emac-mac.c
index bcd4708b3745..3ed9033e56db 100644
--- a/drivers/net/ethernet/qualcomm/emac/emac-mac.c
+++ b/drivers/net/ethernet/qualcomm/emac/emac-mac.c
@@ -551,6 +551,28 @@ static void emac_mac_start(struct emac_adapter *adpt)
 	mac &= ~(HUGEN | VLAN_STRIP | TPAUSE | SIMR | HUGE | MULTI_ALL |
 		 DEBUG_MODE | SINGLE_PAUSE_MODE);
 
+	/* Enable single-pause-frame mode if requested.
+	 *
+	 * If enabled, the EMAC will send a single pause frame when the RX
+	 * queue is full.  This normally leads to packet loss because
+	 * the pause frame disables the remote MAC only for 33ms (the quanta),
+	 * and then the remote MAC continues sending packets even though
+	 * the RX queue is still full.
+	 *
+	 * If disabled, the EMAC sends a pause frame every 31ms until the RX
+	 * queue is no longer full.  Normally, this is the preferred
+	 * method of operation.  However, when the system is hung (e.g.
+	 * cores are halted), the EMAC interrupt handler is never called
+	 * and so the RX queue fills up quickly and stays full.  The resuling
+	 * non-stop "flood" of pause frames sometimes has the effect of
+	 * disabling nearby switches.  In some cases, other nearby switches
+	 * are also affected, shutting down the entire network.
+	 *
+	 * The user can enable or disable single-pause-frame mode
+	 * via ethtool.
+	 */
+	mac |= adpt->single_pause_mode ? SINGLE_PAUSE_MODE : 0;
+
 	writel_relaxed(csr1, adpt->csr + EMAC_EMAC_WRAPPER_CSR1);
 
 	writel_relaxed(mac, adpt->base + EMAC_MAC_CTRL);
@@ -876,7 +898,8 @@ static void emac_mac_rx_descs_refill(struct emac_adapter *adpt,
 
 		curr_rxbuf->dma_addr =
 			dma_map_single(adpt->netdev->dev.parent, skb->data,
-				       curr_rxbuf->length, DMA_FROM_DEVICE);
+				       adpt->rxbuf_size, DMA_FROM_DEVICE);
+
 		ret = dma_mapping_error(adpt->netdev->dev.parent,
 					curr_rxbuf->dma_addr);
 		if (ret) {
diff --git a/drivers/net/ethernet/qualcomm/emac/emac.c b/drivers/net/ethernet/qualcomm/emac/emac.c
index 60850bfa3d32..759543512117 100644
--- a/drivers/net/ethernet/qualcomm/emac/emac.c
+++ b/drivers/net/ethernet/qualcomm/emac/emac.c
@@ -443,6 +443,9 @@ static void emac_init_adapter(struct emac_adapter *adpt)
 
 	/* default to automatic flow control */
 	adpt->automatic = true;
+
+	/* Disable single-pause-frame mode by default */
+	adpt->single_pause_mode = false;
 }
 
 /* Get the clock */
diff --git a/drivers/net/ethernet/qualcomm/emac/emac.h b/drivers/net/ethernet/qualcomm/emac/emac.h
index 8ee4ec6aef2e..d7c9f44209d4 100644
--- a/drivers/net/ethernet/qualcomm/emac/emac.h
+++ b/drivers/net/ethernet/qualcomm/emac/emac.h
@@ -363,6 +363,9 @@ struct emac_adapter {
 	bool				tx_flow_control;
 	bool				rx_flow_control;
 
+	/* True == use single-pause-frame mode. */
+	bool				single_pause_mode;
+
 	/* Ring parameter */
 	u8				tpd_burst;
 	u8				rfd_burst;
diff --git a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
index 98f22551eb45..1e33aea59f50 100644
--- a/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
+++ b/drivers/net/ethernet/qualcomm/rmnet/rmnet_config.c
@@ -51,10 +51,7 @@ struct rmnet_walk_data {
 
 static int rmnet_is_real_dev_registered(const struct net_device *real_dev)
 {
-	rx_handler_func_t *rx_handler;
-
-	rx_handler = rcu_dereference(real_dev->rx_handler);
-	return (rx_handler == rmnet_rx_handler);
+	return rcu_access_pointer(real_dev->rx_handler) == rmnet_rx_handler;
 }
 
 /* Needs rtnl lock */