From 7e31149584ef66676a7f833388266e05b63a9c43 Mon Sep 17 00:00:00 2001
From: "J. Nick Koston" <nick@home-assistant.io>
Date: Sat, 25 Oct 2025 15:02:56 -0700
Subject: [PATCH] readable

---
 esphome/components/usb_uart/usb_uart.cpp | 74 +++++++++++++-----------
 esphome/components/usb_uart/usb_uart.h   |  1 +
 2 files changed, 42 insertions(+), 33 deletions(-)

diff --git a/esphome/components/usb_uart/usb_uart.cpp b/esphome/components/usb_uart/usb_uart.cpp
index 661901d0a8..fa9b5a13b7 100644
--- a/esphome/components/usb_uart/usb_uart.cpp
+++ b/esphome/components/usb_uart/usb_uart.cpp
@@ -184,48 +184,56 @@ void USBUartComponent::restart_input_(USBUartChannel *channel) {
   }
 }
 
-void USBUartComponent::do_start_input_(USBUartChannel *channel) {
-  // This function does the actual work of starting input
-  // Caller must ensure input_started_ is already set to true
-  const auto *ep = channel->cdc_dev_.in_ep;
-  // CALLBACK CONTEXT: This lambda is executed in USB task via transfer_callback
-  auto callback = [this, channel](const usb_host::TransferStatus &status) {
-    ESP_LOGV(TAG, "Transfer result: length: %u; status %X", status.data_len, status.error_code);
-    if (!status.success) {
-      ESP_LOGE(TAG, "Control transfer failed, status=%s", esp_err_to_name(status.error_code));
-      // Transfer failed, slot already released
+void USBUartComponent::input_transfer_callback_(USBUartChannel *channel, const usb_host::TransferStatus &status) {
+  // CALLBACK CONTEXT: This function is executed in USB task via transfer_callback
+  ESP_LOGV(TAG, "Transfer result: length: %u; status %X", status.data_len, status.error_code);
+
+  if (!status.success) {
+    ESP_LOGE(TAG, "Control transfer failed, status=%s", esp_err_to_name(status.error_code));
+    // Transfer failed, slot already released
+    // Reset state so normal operations can restart later
+    this->reset_input_state_(channel);
+    return;
+  }
+
+  if (!channel->dummy_receiver_ && status.data_len > 0) {
+    // Allocate a chunk from the pool
+    UsbDataChunk *chunk = this->chunk_pool_.allocate();
+    if (chunk == nullptr) {
+      // No chunks available - queue is full, data dropped, slot already released
+      this->usb_data_queue_.increment_dropped_count();
       // Reset state so normal operations can restart later
       this->reset_input_state_(channel);
       return;
     }
 
-    if (!channel->dummy_receiver_ && status.data_len > 0) {
-      // Allocate a chunk from the pool
-      UsbDataChunk *chunk = this->chunk_pool_.allocate();
-      if (chunk == nullptr) {
-        // No chunks available - queue is full, data dropped, slot already released
-        this->usb_data_queue_.increment_dropped_count();
-        // Reset state so normal operations can restart later
-        this->reset_input_state_(channel);
-        return;
-      }
+    // Copy data to chunk (this is fast, happens in USB task)
+    memcpy(chunk->data, status.data, status.data_len);
+    chunk->length = status.data_len;
+    chunk->channel = channel;
 
-      // Copy data to chunk (this is fast, happens in USB task)
-      memcpy(chunk->data, status.data, status.data_len);
-      chunk->length = status.data_len;
-      chunk->channel = channel;
+    // Push to lock-free queue for main loop processing
+    // Push always succeeds because pool size == queue size
+    this->usb_data_queue_.push(chunk);
+  }
 
-      // Push to lock-free queue for main loop processing
-      // Push always succeeds because pool size == queue size
-      this->usb_data_queue_.push(chunk);
-    }
+  // On success, reset retry count and restart input immediately from USB task for performance
+  // The lock-free queue will handle backpressure
+  channel->input_retry_count_.store(0);
+  channel->input_started_.store(false);
+  this->start_input(channel);
+}
 
-    // On success, reset retry count and restart input immediately from USB task for performance
-    // The lock-free queue will handle backpressure
-    channel->input_retry_count_.store(0);
-    channel->input_started_.store(false);
-    this->start_input(channel);
+void USBUartComponent::do_start_input_(USBUartChannel *channel) {
+  // This function does the actual work of starting input
+  // Caller must ensure input_started_ is already set to true
+  const auto *ep = channel->cdc_dev_.in_ep;
+
+  // Set up callback using a lambda that captures channel and forwards to the named function
+  auto callback = [this, channel](const usb_host::TransferStatus &status) {
+    this->input_transfer_callback_(channel, status);
   };
+
   // input_started_ already set to true by caller
   auto result = this->transfer_in(ep->bEndpointAddress, callback, ep->wMaxPacketSize);
   if (result == usb_host::TRANSFER_ERROR_NO_SLOTS) {
diff --git a/esphome/components/usb_uart/usb_uart.h b/esphome/components/usb_uart/usb_uart.h
index 330cb119bf..ba7fc3ebe5 100644
--- a/esphome/components/usb_uart/usb_uart.h
+++ b/esphome/components/usb_uart/usb_uart.h
@@ -145,6 +145,7 @@ class USBUartComponent : public usb_host::USBClient {
   void reset_input_state_(USBUartChannel *channel);
   void restart_input_(USBUartChannel *channel);
   void do_start_input_(USBUartChannel *channel);
+  void input_transfer_callback_(USBUartChannel *channel, const usb_host::TransferStatus &status);
   std::vector<USBUartChannel *> channels_{};
 };