Merge pull request adafruit#10293 from tannewt/shrink_host_enum_buffer

tannewt · web-flow · commit 36bc41c5eaa9 · 2025-04-25T14:47:09.000-07:00
Reduce USB static buffers for ESP32-S2
diff --git a/ports/espressif/Makefile b/ports/espressif/Makefile
@@ -360,10 +360,19 @@ CFLAGS += \
 	-DCFG_TUD_TASK_QUEUE_SZ=32
 endif
 ifeq ($(CIRCUITPY_USB_DEVICE),1)
+ifeq ($(IDF_TARGET),esp32s2)
+# Make more room in internal RAM on the S2.
+CFLAGS += \
+	-DCFG_TUD_CDC_RX_BUFSIZE=128 \
+	-DCFG_TUD_CDC_TX_BUFSIZE=128 \
+	-DCFG_TUD_MSC_BUFSIZE=1024
+else
 CFLAGS += \
 	-DCFG_TUD_CDC_RX_BUFSIZE=1024 \
 	-DCFG_TUD_CDC_TX_BUFSIZE=1024 \
-	-DCFG_TUD_MSC_BUFSIZE=4096 \
+	-DCFG_TUD_MSC_BUFSIZE=4096
+endif
+CFLAGS += \
 	-DCFG_TUD_MIDI_RX_BUFSIZE=128 \
 	-DCFG_TUD_MIDI_TX_BUFSIZE=128 \
 	-DCFG_TUD_VENDOR_RX_BUFSIZE=128 \
diff --git a/supervisor/shared/usb/tusb_config.h b/supervisor/shared/usb/tusb_config.h
@@ -172,8 +172,10 @@ extern "C" {
 #endif
 
 // Size of buffer to hold descriptors and other data used for enumeration
+// CircuitPython itself is 284 bytes of configuration descriptor when both CDC endpoints are
+// enabled, plus 4 bytes for alignment.
 #ifndef CFG_TUH_ENUMERATION_BUFSIZE
-#define CFG_TUH_ENUMERATION_BUFSIZE 512
+#define CFG_TUH_ENUMERATION_BUFSIZE (284 + 4)
 #endif
 
 #if CIRCUITPY_USB_KEYBOARD_WORKFLOW
