From d5a9b84809870a39f991b6e2492ae5424773e7a0 Mon Sep 17 00:00:00 2001
From: HiFiPhile <admin@hifiphile.com>
Date: Fri, 5 Apr 2024 13:15:19 +0200
Subject: [PATCH] Correctly use single buffering for ISO.

---
 src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c | 53 ++++++++++---------
 1 file changed, 28 insertions(+), 25 deletions(-)

diff --git a/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c b/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c
index 6f0742c7c0..08d792bfa5 100644
--- a/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c
+++ b/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c
@@ -518,6 +518,11 @@ static void dcd_ep_ctr_tx_handler(uint32_t wIstr)
   pcd_clear_tx_ep_ctr(USB, EPindex);
 
   xfer_ctl_t * xfer = xfer_ctl_ptr(ep_addr);
+
+  if ((wEPRegVal & USB_EP_TYPE_MASK) == USB_EP_ISOCHRONOUS) {
+    pcd_set_ep_tx_cnt(USB, EPindex, 0);
+  }
+
   if((xfer->total_len != xfer->queued_len)) /* TX not complete */
   {
     dcd_transmit_packet(xfer, EPindex);
@@ -587,12 +592,7 @@ static void dcd_ep_ctr_rx_handler(uint32_t wIstr) {
   else
   {
     uint32_t count;
-    /* Read from correct register when ISOCHRONOUS (double buffered) */
-    if ( (wEPRegVal & USB_EP_DTOG_RX) && ( (wEPRegVal & USB_EP_TYPE_MASK) == USB_EP_ISOCHRONOUS) ) {
-      count = pcd_get_ep_tx_cnt(USB, EPindex);
-    } else {
-      count = pcd_get_ep_rx_cnt(USB, EPindex);
-    }
+    count = pcd_get_ep_rx_cnt(USB, EPindex);
 
     TU_ASSERT(count <= xfer->max_packet_size, /**/);
 
@@ -935,7 +935,7 @@ void dcd_edpt_close_all (uint8_t rhport)
  *
  * This also clears transfers in progress, should there be any.
  */
-void dcd_edpt_close (uint8_t rhport, uint8_t ep_addr)
+void dcd_edpt_close(uint8_t rhport, uint8_t ep_addr)
 {
   (void)rhport;
 
@@ -957,9 +957,11 @@ bool dcd_edpt_iso_alloc(uint8_t rhport, uint8_t ep_addr, uint16_t largest_packet
 {
   (void)rhport;
 
-  TU_ASSERT(largest_packet_size <= 1024);
+  // Long packet is not supported
+  TU_ASSERT(largest_packet_size < 512);
 
   uint8_t const ep_idx = dcd_ep_alloc(ep_addr, TUSB_XFER_ISOCHRONOUS);
+  uint8_t const dir    = tu_edpt_dir(ep_addr);
   const uint16_t buffer_size = pcd_aligned_buffer_size(largest_packet_size);
 
   /* Create a packet memory buffer area. For isochronous endpoints,
@@ -970,8 +972,18 @@ bool dcd_edpt_iso_alloc(uint8_t rhport, uint8_t ep_addr, uint16_t largest_packet
 
   pcd_set_eptype(USB, ep_idx, USB_EP_ISOCHRONOUS);
 
-  pcd_set_ep_tx_address(USB, ep_idx, pma_addr);
-  pcd_set_ep_rx_address(USB, ep_idx, pma_addr);
+  // Disable double buffering
+  pcd_set_ep_kind(USB, ep_idx);
+
+  if(dir == TUSB_DIR_IN)
+  {
+    pcd_set_ep_tx_address(USB, ep_idx, pma_addr);
+  }
+
+  if(dir == TUSB_DIR_OUT)
+  {
+    pcd_set_ep_rx_address(USB, ep_idx, pma_addr);
+  }
 
   return true;
 }
@@ -988,21 +1000,17 @@ bool dcd_edpt_iso_activate(uint8_t rhport,  tusb_desc_endpoint_t const * p_endpo
   if(dir == TUSB_DIR_IN)
   {
     pcd_set_ep_tx_status(USB, ep_idx, USB_EP_TX_DIS);
+    pcd_set_ep_tx_bufsize(USB, ep_idx, buffer_size);
+    pcd_clear_tx_dtog(USB, ep_idx);
   }
   else
   {
     pcd_set_ep_rx_status(USB, ep_idx, USB_EP_RX_DIS);
+    pcd_set_ep_rx_bufsize(USB, ep_idx, buffer_size);
+    pcd_clear_rx_dtog(USB, ep_idx);
   }
 
   pcd_set_ep_address(USB, ep_idx, tu_edpt_number(p_endpoint_desc->bEndpointAddress));
-  // Be normal, for now, instead of only accepting zero-byte packets (on control endpoint)
-  // or being double-buffered (bulk endpoints)
-  pcd_clear_ep_kind(USB,0);
-
-  pcd_set_ep_tx_bufsize(USB, ep_idx, buffer_size);
-  pcd_set_ep_rx_bufsize(USB, ep_idx, buffer_size);
-  pcd_clear_tx_dtog(USB, ep_idx);
-  pcd_clear_rx_dtog(USB, ep_idx);
 
   xfer_ctl_ptr(p_endpoint_desc->bEndpointAddress)->max_packet_size = packet_size;
 
@@ -1033,14 +1041,9 @@ static void dcd_transmit_packet(xfer_ctl_t * xfer, uint16_t ep_ix)
   }
   xfer->queued_len = (uint16_t)(xfer->queued_len + len);
 
-  /* Write into correct register when ISOCHRONOUS (double buffered) */
-  if ( (ep_reg & USB_EP_DTOG_TX) && ( (ep_reg & USB_EP_TYPE_MASK) == USB_EP_ISOCHRONOUS) ) {
-    pcd_set_ep_rx_cnt(USB, ep_ix, len);
-  } else {
-    pcd_set_ep_tx_cnt(USB, ep_ix, len);
-  }
-
+  pcd_set_ep_tx_cnt(USB, ep_ix, len);
   pcd_set_ep_tx_status(USB, ep_ix, USB_EP_TX_VALID);
+
 }
 
 bool dcd_edpt_xfer (uint8_t rhport, uint8_t ep_addr, uint8_t * buffer, uint16_t total_bytes)