fix(tcp): MUX模式网口失联 — 对端关闭时用tcp_abort替代tcp_close避免TIME_WAIT耗尽pcb池

根因: tcp_close()将对端关闭的pcb推入TIME_WAIT(120s), 占用MEMP_TCP_PCB池(仅4个),
多连接同时断开后pcb池耗尽, tcp_new()返回NULL, 新连接无法建立直到120s超时释放。

核心修复:
- tcp_server/client: 对端关闭(p=NULL)时tcp_abort替代tcp_close, pcb立即释放
- ch390_runtime: PKT_ERR恢复强制OR上RCR_RXEN(与WCH官方一致)
- ch390_runtime: TX连续超时3次自动emergency reset
- ch390_runtime: 每5秒health_check读VID验证芯片存活
- main: App_StartLinksIfNeeded失败时不标记g_links_started, 允许重试
- main: MUX逐帧RTT printf改为#if DEBUG门控, 减少主循环延迟
- uart_trans: MUX帧解析改为先搜0x7E再消费header, 非法帧只丢1字节

Drivers/CH390/ch390_runtime.c

@@ -38,6 +38,14 @@ static uint8_t ch390_runtime_drain_rx(struct netif *netif, uint8_t max_frames)
 static volatile uint8_t g_ch390_irq_pending;
 static uint8_t g_ch390_ready;
 static ch390_diag_t g_diag;
+static uint8_t g_tx_consecutive_timeout;
+static uint8_t g_chip_reset_count;
+
+#define TX_TIMEOUT_THRESHOLD  3u
+#define CHIP_RESET_MAX        3u
+
+#define TX_TIMEOUT_THRESHOLD  3u
+#define CHIP_RESET_MAX        3u
 
 static uint8_t ch390_runtime_probe_identity(void)
 {
@@ -99,7 +107,7 @@ struct pbuf *ch390_runtime_input_frame(struct netif *netif)
         ch390_write_reg(CH390_MPTRCR, 0x01u);
         ch390_write_reg(CH390_MRRH, 0x0Cu);
         ch390_delay_us(1000u);
-        ch390_write_reg(CH390_RCR, rcr);
+        ch390_write_reg(CH390_RCR, (uint8_t)(rcr | RCR_RXEN));
         ethernetif->rx_len = 0u;
         LINK_STATS_INC(link.drop);
         g_diag.rx_packets_drop++;
@@ -344,10 +352,16 @@ err_t ch390_runtime_output(struct netif *netif, struct pbuf *p)
 #endif
             LINK_STATS_INC(link.drop);
             g_diag.tx_packets_timeout++;
+            g_tx_consecutive_timeout++;
+            if (g_tx_consecutive_timeout >= TX_TIMEOUT_THRESHOLD) {
+                ch390_runtime_emergency_reset();
+            }
             return ERR_TIMEOUT;
         }
     }
 
+    g_tx_consecutive_timeout = 0u;
+
     for (q = p; q != NULL; q = q->next) {
         ch390_write_mem((uint8_t *)q->payload, q->len);
     }
@@ -377,3 +391,55 @@ bool ch390_runtime_is_ready(void)
 {
     return g_ch390_ready != 0u;
 }
+
+bool ch390_runtime_emergency_reset(void)
+{
+    SEGGER_RTT_printf(0, "ETH emergency reset (tx_timeout=%u resets=%u/%u)\r\n",
+                      g_tx_consecutive_timeout, g_chip_reset_count, CHIP_RESET_MAX);
+
+    if (g_chip_reset_count >= CHIP_RESET_MAX) {
+        SEGGER_RTT_WriteString(0, "ETH: max resets reached, giving up\r\n");
+        g_ch390_ready = 0u;
+        return false;
+    }
+
+    g_chip_reset_count++;
+    g_tx_consecutive_timeout = 0u;
+
+    ch390_software_reset();
+    ch390_delay_us(5000u);
+    ch390_default_config();
+
+    ch390_runtime_refresh_diag();
+    g_ch390_ready = g_diag.id_valid;
+
+    if (g_ch390_ready == 0u) {
+        SEGGER_RTT_WriteString(0, "ETH emergency reset: chip not responding\r\n");
+        return false;
+    }
+
+    SEGGER_RTT_WriteString(0, "ETH emergency reset: OK\r\n");
+    return true;
+}
+
+void ch390_runtime_health_check(struct netif *netif)
+{
+    if (!g_ch390_ready) {
+        return;
+    }
+
+    /* Verify chip is still responding by reading vendor ID */
+    uint16_t vid = ch390_get_vendor_id();
+    if (vid == 0x0000u || vid == 0xFFFFu) {
+        SEGGER_RTT_printf(0, "ETH health: invalid VID=0x%04X, attempting reset\r\n", vid);
+        netif_set_link_down(netif);
+        if (ch390_runtime_emergency_reset()) {
+            ch390_runtime_check_link(netif);
+        }
+    }
+}
+
+uint8_t ch390_runtime_get_reset_count(void)
+{
+    return g_chip_reset_count;
+}

Drivers/CH390/ch390_runtime.h

@@ -58,5 +58,8 @@ void ch390_runtime_check_link(struct netif *netif);
 err_t ch390_runtime_output(struct netif *netif, struct pbuf *p);
 void ch390_runtime_get_diag(ch390_diag_t *diag);
 bool ch390_runtime_is_ready(void);
+bool ch390_runtime_emergency_reset(void);
+void ch390_runtime_health_check(struct netif *netif);
+uint8_t ch390_runtime_get_reset_count(void);
 
 #endif