From a6df41d895bb19eecbd16cab9471c82681785d11 Mon Sep 17 00:00:00 2001
From: HiFiPhile <admin@hifiphile.com>
Date: Fri, 21 Nov 2025 15:44:07 +0100
Subject: [PATCH] dcd/dwc2: add IN fifo configure

Signed-off-by: HiFiPhile <admin@hifiphile.com>
---
 src/device/usbd.h                     | 14 ++++++++++++++
 src/portable/synopsys/dwc2/dcd_dwc2.c | 21 +++++++++++++++++----
 2 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/src/device/usbd.h b/src/device/usbd.h
index b40ef6277..781688a8a 100644
--- a/src/device/usbd.h
+++ b/src/device/usbd.h
@@ -33,6 +33,20 @@
 extern "C" {
 #endif
 
+// ConfigID for tuh_configure()
+enum {
+  TUD_CFGID_INVALID = 0,
+  TUD_CFGID_DWC2 = 100,
+};
+
+typedef struct {
+  uint16_t bm_double_buffered; // bitmap of IN endpoints to be double buffered, only effective for bulk endpoints
+} tud_configure_dwc2_t;
+
+typedef union {
+  tud_configure_dwc2_t dwc2;
+} tud_configure_param_t;
+
 //--------------------------------------------------------------------+
 // Application API
 //--------------------------------------------------------------------+
diff --git a/src/portable/synopsys/dwc2/dcd_dwc2.c b/src/portable/synopsys/dwc2/dcd_dwc2.c
index e99cd29c6..477341791 100644
--- a/src/portable/synopsys/dwc2/dcd_dwc2.c
+++ b/src/portable/synopsys/dwc2/dcd_dwc2.c
@@ -39,6 +39,7 @@
 #define DWC2_DEBUG    2
 
 #include "device/dcd.h"
+#include "device/usbd.h"
 #include "device/usbd_pvt.h"
 #include "dwc2_common.h"
 
@@ -76,6 +77,10 @@ CFG_TUD_MEM_SECTION static struct {
   TUD_EPBUF_DEF(setup_packet, 8);
 } _dcd_usbbuf;
 
+static tud_configure_dwc2_t _tud_cfg = {
+  .bm_double_buffered = 0
+};
+
 TU_ATTR_ALWAYS_INLINE static inline uint8_t dwc2_ep_count(const dwc2_regs_t* dwc2) {
   #if TU_CHECK_MCU(OPT_MCU_GD32VF103)
   (void) dwc2;
@@ -212,8 +217,8 @@ static bool dfifo_alloc(uint8_t rhport, uint8_t ep_addr, uint16_t packet_size) {
       _dcd_data.allocated_epin_count++;
     }
 
-    // If The TXFELVL is configured as half empty, the fifo must be twice the max_size.
-    if ((dwc2->gahbcfg & GAHBCFG_TX_FIFO_EPMTY_LVL) == 0) {
+    // Enable double buffering if configured
+    if (((_tud_cfg.bm_double_buffered & (1 << epnum)) != 0) && (epnum > 0)) {
       fifo_size *= 2;
     }
 
@@ -446,6 +451,16 @@ static void edpt_schedule_packets(uint8_t rhport, const uint8_t epnum, const uin
 //--------------------------------------------------------------------
 // Controller API
 //--------------------------------------------------------------------
+// optional dcd configuration, called by tud_configure()
+bool dcd_configure(uint8_t rhport, uint32_t cfg_id, const void* cfg_param) {
+  (void) rhport;
+  TU_VERIFY(cfg_id == TUD_CFGID_DWC2 && cfg_param != NULL);
+
+  const tud_configure_param_t* const cfg = (const tud_configure_param_t*) cfg_param;
+  _tud_cfg = cfg->dwc2;
+  return true;
+}
+
 bool dcd_init(uint8_t rhport, const tusb_rhport_init_t* rh_init) {
   (void) rh_init;
   dwc2_regs_t* dwc2 = DWC2_REG(rhport);
@@ -492,9 +507,7 @@ bool dcd_init(uint8_t rhport, const tusb_rhport_init_t* rh_init) {
   // Enable required interrupts
   dwc2->gintmsk |= GINTMSK_OTGINT | GINTMSK_USBRST | GINTMSK_ENUMDNEM | GINTMSK_WUIM;
 
-  // TX FIFO empty level for interrupt is complete empty
   uint32_t gahbcfg = dwc2->gahbcfg;
-  gahbcfg |= GAHBCFG_TX_FIFO_EPMTY_LVL;
   gahbcfg |= GAHBCFG_GINT; // Enable global interrupt
   dwc2->gahbcfg = gahbcfg;