From a635aa04e0a17ec46d6cf1162261bb2895e73a5c Mon Sep 17 00:00:00 2001
From: Ian Gulliver <github@flamingcow.io>
Date: Sat, 11 Apr 2026 21:51:22 +0900
Subject: [PATCH] Level-triggered w6300 interrupt, drain until empty, rearm
 after drain

---
 firmware/lib/net.cpp     |  6 ++----
 firmware/w6300/w6300.cpp | 11 +++++++++--
 firmware/w6300/w6300.h   |  1 +
 3 files changed, 12 insertions(+), 6 deletions(-)

diff --git a/firmware/lib/net.cpp b/firmware/lib/net.cpp
index 87784d9..8c645c4 100644
--- a/firmware/lib/net.cpp
+++ b/firmware/lib/net.cpp
@@ -137,13 +137,11 @@ void net_poll(std::span<uint8_t> tx) {
     w6300::irq_pending = false;
     w6300::clear_interrupt(w6300::ik_int_all);
     static uint8_t rx_buf[1518];
-    uint16_t available = w6300::get_socket_recv_buf(raw_socket);
-    uint16_t consumed = 0;
-    while (consumed < available) {
+    while (w6300::get_socket_recv_buf(raw_socket) > 0) {
         auto result = w6300::recv(raw_socket, std::span{rx_buf});
         if (!result) break;
-        consumed += *result + 2;
         span_writer tx_writer(tx);
         process_frame({rx_buf, *result}, tx_writer);
     }
+    w6300::rearm_gpio_irq();
 }
diff --git a/firmware/w6300/w6300.cpp b/firmware/w6300/w6300.cpp
index 365e38b..e11c9c4 100644
--- a/firmware/w6300/w6300.cpp
+++ b/firmware/w6300/w6300.cpp
@@ -77,8 +77,11 @@ void pio_init() {
     gpio_init(PIN_INT);
     gpio_set_dir(PIN_INT, GPIO_IN);
     gpio_pull_up(PIN_INT);
-    gpio_set_irq_enabled_with_callback(PIN_INT, GPIO_IRQ_EDGE_FALL, true,
-        [](uint, uint32_t){ irq_pending = true; });
+    gpio_set_irq_enabled_with_callback(PIN_INT, GPIO_IRQ_LEVEL_LOW, true,
+        [](uint gpio, uint32_t){
+            irq_pending = true;
+            gpio_set_irq_enabled(gpio, GPIO_IRQ_LEVEL_LOW, false);
+        });
 
     pio_hw_t *pios[2] = {pio0, pio1};
     uint pio_index = 1;
@@ -500,6 +503,10 @@ void clear_interrupt(intr_kind intr) {
     set_slirclr((uint8_t)((uint32_t)intr >> 16));
 }
 
+void rearm_gpio_irq() {
+    gpio_set_irq_enabled(PIN_INT, GPIO_IRQ_LEVEL_LOW, true);
+}
+
 void set_interrupt_mask(intr_kind intr) {
     set_imr((uint8_t)intr);
     set_simr((uint8_t)((uint16_t)intr >> 8));
diff --git a/firmware/w6300/w6300.h b/firmware/w6300/w6300.h
index 00c4037..ccd70e2 100644
--- a/firmware/w6300/w6300.h
+++ b/firmware/w6300/w6300.h
@@ -41,6 +41,7 @@ extern volatile bool irq_pending;
 
 void clear_interrupt(intr_kind intr);
 void set_interrupt_mask(intr_kind intr);
+void rearm_gpio_irq();
 
 std::expected<socket_id, sock_error> open_socket(socket_id sn, protocol proto, sock_flag flag);
 std::expected<uint16_t, sock_error> send(socket_id sn, std::span<const uint8_t> buf);