net: airoha: Do not stop GDM port if it is shared

Theoretically, in the current codebase, two independent net_devices can
be connected to the same GDM port so we need to check the GDM port is not
used by any other running net_device before setting the forward
configuration to FE_PSE_PORT_DROP.
Moreover, always set in GDM_LONG_LEN_MASK field of REG_GDM_LEN_CFG
register the maximum MTU of all running net_devices connected to the same
GDM port.

Tested-by: Xuegang Lu <xuegang.lu@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260603-airoha-eth-multi-serdes-v9-4-5d476bc2f426@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/airoha/airoha_eth.c b/drivers/net/ethernet/airoha/airoha_eth.c
index 6d7556c4bee7cb01e95b5b5dc7ba1fd8eac4dc4f..4509281c3c7bc928d077a06221599c1afa8fc53c 100644 (file)
--- a/drivers/net/ethernet/airoha/airoha_eth.c
+++ b/drivers/net/ethernet/airoha/airoha_eth.c
@@ -1720,8 +1720,8 @@ static int airoha_dev_open(struct net_device *netdev)
        int err, len = ETH_HLEN + netdev->mtu + ETH_FCS_LEN;
        struct airoha_gdm_dev *dev = netdev_priv(netdev);
        struct airoha_gdm_port *port = dev->port;
+       u32 cur_len, pse_port = FE_PSE_PORT_PPE1;
        struct airoha_qdma *qdma = dev->qdma;
-       u32 pse_port = FE_PSE_PORT_PPE1;
 
        netif_tx_start_all_queues(netdev);
        err = airoha_set_vip_for_gdm_port(dev, true);
@@ -1735,10 +1735,20 @@ static int airoha_dev_open(struct net_device *netdev)
                airoha_fe_clear(qdma->eth, REG_GDM_INGRESS_CFG(port->id),
                                GDM_STAG_EN_MASK);
 
-       airoha_fe_rmw(qdma->eth, REG_GDM_LEN_CFG(port->id),
-                     GDM_SHORT_LEN_MASK | GDM_LONG_LEN_MASK,
-                     FIELD_PREP(GDM_SHORT_LEN_MASK, 60) |
-                     FIELD_PREP(GDM_LONG_LEN_MASK, len));
+       cur_len = airoha_fe_get(qdma->eth, REG_GDM_LEN_CFG(port->id),
+                               GDM_LONG_LEN_MASK);
+       if (!port->users || len > cur_len) {
+               /* Opening a sibling net_device with a larger MTU updates the
+                * MTU of already running devices. This is required to allow
+                * multiple net_devices with different MTUs to share the same
+                * GDM port.
+                */
+               airoha_fe_rmw(qdma->eth, REG_GDM_LEN_CFG(port->id),
+                             GDM_SHORT_LEN_MASK | GDM_LONG_LEN_MASK,
+                             FIELD_PREP(GDM_SHORT_LEN_MASK, 60) |
+                             FIELD_PREP(GDM_LONG_LEN_MASK, len));
+       }
+       port->users++;
 
        airoha_qdma_set(qdma, REG_QDMA_GLOBAL_CFG,
                        GLOBAL_CFG_TX_DMA_EN_MASK |
@@ -1754,6 +1764,30 @@ static int airoha_dev_open(struct net_device *netdev)
        return 0;
 }
 
+static void airoha_set_port_mtu(struct airoha_eth *eth,
+                               struct airoha_gdm_port *port)
+{
+       u32 len = 0;
+       int i;
+
+       for (i = 0; i < ARRAY_SIZE(port->devs); i++) {
+               struct airoha_gdm_dev *dev = port->devs[i];
+               struct net_device *netdev;
+
+               if (!dev)
+                       continue;
+
+               netdev = netdev_from_priv(dev);
+               if (netif_running(netdev))
+                       len = max_t(u32, len, netdev->mtu);
+       }
+       len += ETH_HLEN + ETH_FCS_LEN;
+
+       airoha_fe_rmw(eth, REG_GDM_LEN_CFG(port->id),
+                     GDM_LONG_LEN_MASK,
+                     FIELD_PREP(GDM_LONG_LEN_MASK, len));
+}
+
 static int airoha_dev_stop(struct net_device *netdev)
 {
        struct airoha_gdm_dev *dev = netdev_priv(netdev);
@@ -1766,8 +1800,12 @@ static int airoha_dev_stop(struct net_device *netdev)
        for (i = 0; i < netdev->num_tx_queues; i++)
                netdev_tx_reset_subqueue(netdev, i);
 
-       airoha_set_gdm_port_fwd_cfg(qdma->eth, REG_GDM_FWD_CFG(port->id),
-                                   FE_PSE_PORT_DROP);
+       if (--port->users)
+               airoha_set_port_mtu(dev->eth, port);
+       else
+               airoha_set_gdm_port_fwd_cfg(qdma->eth,
+                                           REG_GDM_FWD_CFG(port->id),
+                                           FE_PSE_PORT_DROP);
 
        if (atomic_dec_and_test(&qdma->users)) {
                airoha_qdma_clear(qdma, REG_QDMA_GLOBAL_CFG,
@@ -1922,13 +1960,10 @@ static int airoha_dev_change_mtu(struct net_device *netdev, int mtu)
 {
        struct airoha_gdm_dev *dev = netdev_priv(netdev);
        struct airoha_gdm_port *port = dev->port;
-       u32 len = ETH_HLEN + mtu + ETH_FCS_LEN;
-       struct airoha_eth *eth = dev->eth;
 
-       airoha_fe_rmw(eth, REG_GDM_LEN_CFG(port->id),
-                     GDM_LONG_LEN_MASK,
-                     FIELD_PREP(GDM_LONG_LEN_MASK, len));
        WRITE_ONCE(netdev->mtu, mtu);
+       if (port->users)
+               airoha_set_port_mtu(dev->eth, port);
 
        return 0;
 }

diff --git a/drivers/net/ethernet/airoha/airoha_eth.h b/drivers/net/ethernet/airoha/airoha_eth.h
index 92fd81bb926953ed20c46d4e6dd20d420703a5c1..666e9246e70e6d6af6753d61581ff5c7cc120bff 100644 (file)
--- a/drivers/net/ethernet/airoha/airoha_eth.h
+++ b/drivers/net/ethernet/airoha/airoha_eth.h
@@ -554,6 +554,7 @@ struct airoha_gdm_dev {
 struct airoha_gdm_port {
        struct airoha_gdm_dev *devs[AIROHA_MAX_NUM_GDM_DEVS];
        int id;
+       int users;
 
        struct airoha_hw_stats stats;