realtek: eth: prepare counters for fragments

Until now the driver packs each received packet into one ring buffer.
In the future jumbo packets will be split into multiple fragments.
Prepare the ring counters for this:

- Add the more flag to SoC packet header. This denotes if a packet
  has more data after the current fragment.
- Ring counters must be handled per packet and not per fragment.
  Increase work_done after each packet and not after each fragment.

Link: https://github.com/openwrt/openwrt/pull/24245
Signed-off-by: Markus Stockhausen <markus.stockhausen@gmx.de>

diff --git a/target/linux/realtek/files-6.18/drivers/net/ethernet/rtl838x_eth.c b/target/linux/realtek/files-6.18/drivers/net/ethernet/rtl838x_eth.c
index b955219c92874a9953cb134f04f5744f335f78ef..d9eb474ecbbc2ea3c2edf736df8ebbbb83856ec9 100644 (file)
--- a/target/linux/realtek/files-6.18/drivers/net/ethernet/rtl838x_eth.c
+++ b/target/linux/realtek/files-6.18/drivers/net/ethernet/rtl838x_eth.c
@@ -42,6 +42,7 @@
 #define RX_TRUNCATE_EN_83XX            BIT(4)
 #define TX_PAD_EN_838X                 BIT(5)
 
+#define SKB_MTU                                1600
 #define SKB_FRAG_SIZE                  1600
 #define SKB_PAD                                MAX(32, L1_CACHE_BYTES)
 #define SKB_HEADROOM_FAST              (SKB_PAD + NET_IP_ALIGN)
@@ -57,7 +58,8 @@ struct rteth_packet {
        dma_addr_t              dma;
        u16                     reserved;
        u16                     size;
-       u16                     offset;
+       u16                     more:1;
+       u16                     offset:15;
        u16                     len;
        u16                     cpu_tag[10];
        /* software mangement and data part */
@@ -466,16 +468,23 @@ static void rteth_839x_hw_reset(struct rteth_ctrl *ctrl)
 
 static void rteth_93xx_hw_reset(struct rteth_ctrl *ctrl)
 {
+       /*
+        * The counter registers track the number of packets that are allowed to be appended to
+        * the ring buffer. On RTL93xx a ring overflow must be avoided at all cost. Defensively
+        * calculate the space by anticipating that only fully filled packets are received.
+        */
+       int max_frame_size = SKB_MTU + ETH_HLEN + ETH_FCS_LEN + VLAN_HLEN + 4;
+       int frags_per_pkt = DIV_ROUND_UP(max_frame_size, SKB_FRAG_SIZE);
+       int cnt = min(RTETH_RX_RING_SIZE / frags_per_pkt, 0x3ff);
+
        rteth_nic_reset(ctrl, 0x6);
 
        /* Setup Head of Line */
        for (int ring = 0; ring < RTETH_RX_RINGS; ring++) {
-               int cnt = min(RTETH_RX_RING_SIZE, 0x3ff);
                int shift = (ring % 3) * 10;
                int reg = (ring / 3) * 4;
                u32 v;
 
-               /* set ring size */
                regmap_update_bits(ctrl->map, ctrl->r->dma_if_rx_ring_size + reg,
                                   0x3ff << shift, cnt << shift);
                /* clear counters by simply writing the current register values back */
@@ -544,9 +553,9 @@ static void rteth_hw_ring_setup(struct rteth_ctrl *ctrl)
 
 static void rteth_838x_hw_en_rxtx(struct rteth_ctrl *ctrl)
 {
-       /* Truncate RX buffer to DEFAULT_MTU bytes, pad TX */
+       /* Truncate RX buffer to SKB_MTU bytes, pad TX */
        regmap_write(ctrl->map, ctrl->r->dma_if_ctrl,
-                    (DEFAULT_MTU << 16) | RX_TRUNCATE_EN_83XX | TX_PAD_EN_838X);
+                    (SKB_MTU << 16) | RX_TRUNCATE_EN_83XX | TX_PAD_EN_838X);
 
        rteth_enable_all_rx_irqs(ctrl);
 
@@ -570,7 +579,7 @@ static void rteth_838x_hw_en_rxtx(struct rteth_ctrl *ctrl)
 static void rteth_839x_hw_en_rxtx(struct rteth_ctrl *ctrl)
 {
        /* Setup CPU-Port: RX Buffer */
-       regmap_write(ctrl->map, ctrl->r->dma_if_ctrl, (DEFAULT_MTU << 5) | RX_TRUNCATE_EN_83XX);
+       regmap_write(ctrl->map, ctrl->r->dma_if_ctrl, (SKB_MTU << 5) | RX_TRUNCATE_EN_83XX);
 
        rteth_enable_all_rx_irqs(ctrl);
 
@@ -593,8 +602,8 @@ static void rteth_839x_hw_en_rxtx(struct rteth_ctrl *ctrl)
 
 static void rteth_930x_hw_en_rxtx(struct rteth_ctrl *ctrl)
 {
-       /* Setup CPU-Port: RX Buffer truncated at DEFAULT_MTU Bytes */
-       regmap_write(ctrl->map, ctrl->r->dma_if_ctrl, (DEFAULT_MTU << 16) | RX_TRUNCATE_EN_93XX);
+       /* Setup CPU-Port: RX Buffer truncated at SKB_MTU Bytes */
+       regmap_write(ctrl->map, ctrl->r->dma_if_ctrl, (SKB_MTU << 16) | RX_TRUNCATE_EN_93XX);
 
        rteth_enable_all_rx_irqs(ctrl);
 
@@ -610,8 +619,8 @@ static void rteth_930x_hw_en_rxtx(struct rteth_ctrl *ctrl)
 
 static void rteth_931x_hw_en_rxtx(struct rteth_ctrl *ctrl)
 {
-       /* Setup CPU-Port: RX Buffer truncated at DEFAULT_MTU Bytes */
-       regmap_write(ctrl->map, ctrl->r->dma_if_ctrl, (DEFAULT_MTU << 16) | RX_TRUNCATE_EN_93XX);
+       /* Setup CPU-Port: RX Buffer truncated at SKB_MTU Bytes */
+       regmap_write(ctrl->map, ctrl->r->dma_if_ctrl, (SKB_MTU << 16) | RX_TRUNCATE_EN_93XX);
 
        rteth_enable_all_rx_irqs(ctrl);
 
@@ -1118,6 +1127,7 @@ static int rteth_hw_receive(struct net_device *dev, int ring, int budget)
        dma_addr_t packet_dma;
        struct sk_buff *skb;
        struct dsa_tag tag;
+       bool is_tail;
 
        while (work_done < budget) {
                slot = ctrl->rx_data[ring].slot;
@@ -1129,6 +1139,9 @@ static int rteth_hw_receive(struct net_device *dev, int ring, int budget)
 
                packet = &ctrl->rx_data[ring].packet[slot];
                len = packet->len - ETH_FCS_LEN;
+               is_tail = !packet->more;
+               if (is_tail)
+                       work_done++;
 
                if (unlikely(len > SKB_FRAG_SIZE)) {
                        netdev_err(dev, "invalid packet with %d bytes received\n", len);
@@ -1189,7 +1202,6 @@ recycle:
                dma_wmb();
                ctrl->rx_data[ring].ring[slot] = packet_dma | RING_OWN_HW;
                ctrl->rx_data[ring].slot = (slot + 1) % RTETH_RX_RING_SIZE;
-               work_done++;
        }
 
        spin_lock(&ctrl->rx_lock);
@@ -1702,7 +1714,7 @@ static int rteth_probe(struct platform_device *pdev)
 
        dev->ethtool_ops = &rteth_ethtool_ops;
        dev->min_mtu = ETH_ZLEN;
-       dev->max_mtu = DEFAULT_MTU;
+       dev->max_mtu = SKB_MTU;
        dev->features = NETIF_F_RXCSUM;
        dev->hw_features = NETIF_F_RXCSUM;
        dev->netdev_ops = ctrl->r->netdev_ops;

diff --git a/target/linux/realtek/files-6.18/drivers/net/ethernet/rtl838x_eth.h b/target/linux/realtek/files-6.18/drivers/net/ethernet/rtl838x_eth.h
index 9d6837e915bfc8dbc7fd1a7cb70c33802e0971f3..052dcf21efdbfdf580d76af0fd5269fd05ba829c 100644 (file)
--- a/target/linux/realtek/files-6.18/drivers/net/ethernet/rtl838x_eth.h
+++ b/target/linux/realtek/files-6.18/drivers/net/ethernet/rtl838x_eth.h
@@ -181,9 +181,6 @@
 
 #define RTL93XX_CPU_TAG1_IGNORE_STP_MASK       GENMASK(2, 2)
 
-/* Default MTU with jumbo frames support */
-#define DEFAULT_MTU 9000
-
 struct p_hdr;
 struct dsa_tag;
 struct rteth_ctrl;