fix(dwc2): fail missed isochronous frames

A frame-overrun interrupt means the selected periodic service interval has already been missed. Retrying an isochronous transfer after that point cannot deliver the original packet and can leave the class waiting indefinitely for a terminal result.

Enable frame-overrun interrupts for slave periodic channels. Complete isochronous IN and OUT overruns as XFER_RESULT_FAILED in both slave and DMA modes, accounting for bytes already written on OUT. Preserve the existing retry behavior for non-isochronous DMA transfers.

This reports the missed packet honestly through the normal HCD completion path: no fabricated success and no class-level abort workaround.

1 files changed, 28 insertions, 2 deletions

diff --git a/src/portable/synopsys/dwc2/hcd_dwc2.c b/src/portable/synopsys/dwc2/hcd_dwc2.c
index d10f28f6a..55a15b326 100644
--- a/src/portable/synopsys/dwc2/hcd_dwc2.c
+++ b/src/portable/synopsys/dwc2/hcd_dwc2.c
@@ -666,6 +666,9 @@ static bool channel_xfer_start(dwc2_regs_t* dwc2, uint8_t ch_id) {
     }
   } else {
     uint32_t hcintmsk = HCINT_NAK | HCINT_XACT_ERR | HCINT_STALL | HCINT_XFER_COMPLETE | HCINT_DATATOGGLE_ERR;
+    if (is_period) {
+      hcintmsk |= HCINT_FARME_OVERRUN;
+    }
     if (hcchar_bm->ep_dir == TUSB_DIR_IN) {
       hcintmsk |= HCINT_BABBLE_ERR | HCINT_DATATOGGLE_ERR | HCINT_ACK;
     } else {
@@ -1015,6 +1018,11 @@ static bool handle_channel_in_slave(dwc2_regs_t* dwc2, uint8_t ch_id, uint32_t h
     } else {
       channel_disable(dwc2, channel);
     }
+  } else if (hcint & HCINT_FARME_OVERRUN) {
+    if (edpt->hcchar_bm.ep_type == HCCHAR_EPTYPE_ISOCHRONOUS) {
+      xfer->result = XFER_RESULT_FAILED;
+    }
+    channel_disable(dwc2, channel);
   } else if (hcint & (HCINT_XACT_ERR | HCINT_BABBLE_ERR | HCINT_STALL)) {
     if (hcint & HCINT_STALL) {
       xfer->result = XFER_RESULT_STALLED;
@@ -1108,6 +1116,12 @@ static bool handle_channel_out_slave(dwc2_regs_t* dwc2, uint8_t ch_id, uint32_t
   } else if (hcint & HCINT_STALL) {
     xfer->result = XFER_RESULT_STALLED;
     channel_disable(dwc2, channel);
+  } else if (hcint & HCINT_FARME_OVERRUN) {
+    channel_xfer_out_wrapup(dwc2, ch_id);
+    if (edpt->hcchar_bm.ep_type == HCCHAR_EPTYPE_ISOCHRONOUS) {
+      xfer->result = XFER_RESULT_FAILED;
+    }
+    channel_disable(dwc2, channel);
   } else if (hcint & HCINT_NYET) {
     xfer->err_count = 0;
     if (hcsplt.split_en == 1u) {
@@ -1273,8 +1287,12 @@ static bool handle_channel_in_dma(dwc2_regs_t* dwc2, uint8_t ch_id, uint32_t hci
         channel_xfer_in_retry(dwc2, ch_id, hcint);
       }
     } else if (hcint & HCINT_FARME_OVERRUN) {
-      // retry start-split in next binterval
-      channel_xfer_in_retry(dwc2, ch_id, hcint);
+      if (hcchar.ep_type == HCCHAR_EPTYPE_ISOCHRONOUS) {
+        xfer->result = XFER_RESULT_FAILED;
+        is_done      = true;
+      } else {
+        channel_xfer_in_retry(dwc2, ch_id, hcint);
+      }
     }
 
     if (xfer->closing == 1) {
@@ -1341,6 +1359,14 @@ static bool handle_channel_out_dma(dwc2_regs_t* dwc2, uint8_t ch_id, uint32_t hc
          }
        }
      }
+    } else if (hcint & HCINT_FARME_OVERRUN) {
+      channel_xfer_out_wrapup(dwc2, ch_id);
+      if (edpt->hcchar_bm.ep_type == HCCHAR_EPTYPE_ISOCHRONOUS) {
+        xfer->result = XFER_RESULT_FAILED;
+        is_done      = true;
+      } else {
+        channel_xfer_start(dwc2, ch_id);
+      }
     } else if (hcint & HCINT_NYET) {
       if (hcsplt.split_en && hcsplt.split_compl) {
         // split not yet mean hub has no data, retry complete split