[usb_host][usb_uart] Add configurable max packet size (#14584)

esphome/components/usb_host/__init__.py

@@ -10,6 +10,7 @@ from esphome.components.esp32 import (
 )
 import esphome.config_validation as cv
 from esphome.const import CONF_DEVICES, CONF_ID
+from esphome.core import CORE
 from esphome.cpp_types import Component
 from esphome.types import ConfigType
 
@@ -19,14 +20,15 @@ DEPENDENCIES = ["esp32"]
 usb_host_ns = cg.esphome_ns.namespace("usb_host")
 USBHost = usb_host_ns.class_("USBHost", Component)
 USBClient = usb_host_ns.class_("USBClient", Component)
-
+DOMAIN = "usb_host"
 CONF_VID = "vid"
 CONF_PID = "pid"
 CONF_ENABLE_HUBS = "enable_hubs"
 CONF_MAX_TRANSFER_REQUESTS = "max_transfer_requests"
+CONF_MAX_PACKET_SIZE = "max_packet_size"
 
 
-def usb_device_schema(cls=USBClient, vid: int = None, pid: [int] = None) -> cv.Schema:
+def usb_device_schema(cls=USBClient, vid: int = None, pid: int = None) -> cv.Schema:
     schema = cv.COMPONENT_SCHEMA.extend(
         {
             cv.GenerateID(): cv.declare_id(cls),
@@ -43,6 +45,17 @@ def usb_device_schema(cls=USBClient, vid: int = None, pid: [int] = None) -> cv.S
     return schema
 
 
+def _set_max_packet_size(config: dict) -> dict:
+    CORE.data.setdefault(DOMAIN, {})[CONF_MAX_PACKET_SIZE] = config[
+        CONF_MAX_PACKET_SIZE
+    ]
+    return config
+
+
+def get_max_packet_size() -> int:
+    return CORE.data.get(DOMAIN, {}).get(CONF_MAX_PACKET_SIZE, 64)
+
+
 CONFIG_SCHEMA = cv.All(
     cv.COMPONENT_SCHEMA.extend(
         {
@@ -51,10 +64,14 @@ CONFIG_SCHEMA = cv.All(
             cv.Optional(CONF_MAX_TRANSFER_REQUESTS, default=16): cv.int_range(
                 min=1, max=32
             ),
+            cv.Optional(CONF_MAX_PACKET_SIZE, default=64): cv.one_of(
+                64, 128, 256, 512, 1024, int=True
+            ),
             cv.Optional(CONF_DEVICES): cv.ensure_list(usb_device_schema()),
         }
     ),
     only_on_variant(supported=[VARIANT_ESP32P4, VARIANT_ESP32S2, VARIANT_ESP32S3]),
+    _set_max_packet_size,
 )
 
 
@@ -72,8 +89,8 @@ async def to_code(config: ConfigType) -> None:
     if config.get(CONF_ENABLE_HUBS):
         add_idf_sdkconfig_option("CONFIG_USB_HOST_HUBS_SUPPORTED", True)
 
-    max_requests = config[CONF_MAX_TRANSFER_REQUESTS]
-    cg.add_define("USB_HOST_MAX_REQUESTS", max_requests)
+    cg.add_define("USB_HOST_MAX_REQUESTS", config[CONF_MAX_TRANSFER_REQUESTS])
+    cg.add_define("USB_HOST_MAX_PACKET_SIZE", config[CONF_MAX_PACKET_SIZE])
 
     var = cg.new_Pvariable(config[CONF_ID])
     await cg.register_component(var, config)

esphome/components/usb_host/usb_host.h

@@ -66,6 +66,8 @@ static_assert(MAX_REQUESTS >= 1 && MAX_REQUESTS <= 32, "MAX_REQUESTS must be bet
 using trq_bitmask_t = std::conditional<(MAX_REQUESTS <= 16), uint16_t, uint32_t>::type;
 static constexpr trq_bitmask_t ALL_REQUESTS_IN_USE = MAX_REQUESTS == 32 ? ~0 : (1 << MAX_REQUESTS) - 1;
 
+static constexpr size_t USB_MAX_PACKET_SIZE =
+    USB_HOST_MAX_PACKET_SIZE;                        // Max USB packet size (64 for FS, 512 for P4 HS)
 static constexpr size_t USB_EVENT_QUEUE_SIZE = 32;   // Size of event queue between USB task and main loop
 static constexpr size_t USB_TASK_STACK_SIZE = 4096;  // Stack size for USB task (same as ESP-IDF USB examples)
 static constexpr UBaseType_t USB_TASK_PRIORITY = 5;  // Higher priority than main loop (tskIDLE_PRIORITY + 5)

esphome/components/usb_host/usb_host_client.cpp

@@ -217,7 +217,7 @@ void USBClient::setup() {
   // Pre-allocate USB transfer buffers for all slots at startup
   // This avoids any dynamic allocation during runtime
   for (auto &request : this->requests_) {
-    usb_host_transfer_alloc(64, 0, &request.transfer);
+    usb_host_transfer_alloc(USB_MAX_PACKET_SIZE, 0, &request.transfer);
     request.client = this;  // Set once, never changes
   }
 

esphome/components/usb_uart/__init__.py

@@ -1,7 +1,11 @@
 import esphome.codegen as cg
 from esphome.components.const import CONF_DATA_BITS, CONF_PARITY, CONF_STOP_BITS
 from esphome.components.uart import CONF_DEBUG_PREFIX, CONF_FLUSH_TIMEOUT, UARTComponent
-from esphome.components.usb_host import register_usb_client, usb_device_schema
+from esphome.components.usb_host import (
+    get_max_packet_size,
+    register_usb_client,
+    usb_device_schema,
+)
 import esphome.config_validation as cv
 from esphome.const import (
     CONF_BAUD_RATE,
@@ -118,14 +122,14 @@ CONFIG_SCHEMA = cv.ensure_list(
 async def to_code(config):
     # The output chunk pool/queue are compile-time-sized templates shared by all
     # USBUartChannel instances, so use the largest buffer_size across every channel
-    # of every device.  Each chunk is 64 bytes (USB FS MPS); add one extra slot
-    # because LockFreeQueue<T,N> is a ring buffer that wastes one entry.
+    # of every device. Add one extra slot because LockFreeQueue<T,N> is a ring
+    # buffer that wastes one entry.
     max_buffer_size = max(
         channel[CONF_BUFFER_SIZE]
         for device in config
         for channel in device[CONF_CHANNELS]
     )
-    output_chunk_count = max_buffer_size // 64 + 1
+    output_chunk_count = max(max_buffer_size // get_max_packet_size(), 2) + 1
     cg.add_define("USB_UART_OUTPUT_CHUNK_COUNT", output_chunk_count)
 
     for device in config:

esphome/components/usb_uart/usb_uart.cpp

@@ -157,7 +157,7 @@ void USBUartChannel::write_array(const uint8_t *data, size_t len) {
       ESP_LOGE(TAG, "Output pool full - lost %zu bytes", len);
       break;
     }
-    size_t chunk_len = std::min(len, UsbOutputChunk::MAX_CHUNK_SIZE);
+    uint16_t chunk_len = std::min(len, UsbOutputChunk::MAX_CHUNK_SIZE);
     memcpy(chunk->data, data, chunk_len);
     chunk->length = static_cast<uint8_t>(chunk_len);
     // Push always succeeds: pool is sized to queue capacity (SIZE-1), so if
@@ -222,7 +222,7 @@ void USBUartComponent::loop() {
 
 #ifdef USE_UART_DEBUGGER
     if (channel->debug_) {
-      char buf[4 + format_hex_pretty_size(UsbDataChunk::MAX_CHUNK_SIZE)];  // "<<< " + hex
+      char buf[4 + format_hex_pretty_size(usb_host::USB_MAX_PACKET_SIZE)];  // "<<< " + hex
       memcpy(buf, "<<< ", 4);
       format_hex_pretty_to(buf + 4, sizeof(buf) - 4, chunk->data, chunk->length, ',');
       ESP_LOGD(TAG, "%s%s", channel->debug_prefix_.c_str(), buf);
@@ -377,7 +377,7 @@ void USBUartComponent::start_output(USBUartChannel *channel) {
     this->start_output(channel);
   };
 
-  const uint8_t len = chunk->length;
+  const auto len = chunk->length;
   if (!this->transfer_out(ep->bEndpointAddress, callback, chunk->data, len)) {
     // Transfer submission failed — return chunk and release flag so callers can retry.
     channel->output_pool_.release(chunk);
@@ -394,10 +394,10 @@ void USBUartComponent::start_output(USBUartChannel *channel) {
 static void fix_mps(const usb_ep_desc_t *ep) {
   if (ep != nullptr) {
     auto *ep_mutable = const_cast<usb_ep_desc_t *>(ep);
-    if (ep->wMaxPacketSize > 64) {
-      ESP_LOGW(TAG, "Corrected MPS of EP 0x%02X from %u to 64", static_cast<uint8_t>(ep->bEndpointAddress & 0xFF),
-               ep->wMaxPacketSize);
-      ep_mutable->wMaxPacketSize = 64;
+    if (ep->wMaxPacketSize > usb_host::USB_MAX_PACKET_SIZE) {
+      ESP_LOGW(TAG, "Corrected MPS of EP 0x%02X from %u to %u", static_cast<uint8_t>(ep->bEndpointAddress & 0xFF),
+               ep->wMaxPacketSize, usb_host::USB_MAX_PACKET_SIZE);
+      ep_mutable->wMaxPacketSize = usb_host::USB_MAX_PACKET_SIZE;
     }
   }
 }

esphome/components/usb_uart/usb_uart.h

@@ -106,20 +106,19 @@ class RingBuffer {
 
 // Structure for queuing received USB data chunks
 struct UsbDataChunk {
-  static constexpr size_t MAX_CHUNK_SIZE = 64;  // USB packet size
-  uint8_t data[MAX_CHUNK_SIZE];
-  uint8_t length;  // Max 64 bytes, so uint8_t is sufficient
+  uint8_t data[usb_host::USB_MAX_PACKET_SIZE];
+  uint16_t length;
   USBUartChannel *channel;
 
   // Required for EventPool - no cleanup needed for POD types
   void release() {}
 };
 
-// Structure for queuing outgoing USB data chunks (one per USB FS packet)
+// Structure for queuing outgoing USB data chunks (one per USB packet)
 struct UsbOutputChunk {
-  static constexpr size_t MAX_CHUNK_SIZE = 64;  // USB FS MPS
+  static constexpr size_t MAX_CHUNK_SIZE = usb_host::USB_MAX_PACKET_SIZE;
   uint8_t data[MAX_CHUNK_SIZE];
-  uint8_t length;
+  uint16_t length;
 
   // Required for EventPool - no cleanup needed for POD types
   void release() {}