Fix buf_id read for ISO transfer.

1 files changed, 1 insertions, 2 deletions

diff --git a/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c b/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c
index ed9036d19..0cdc3eef9 100644
--- a/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c
+++ b/src/portable/st/stm32_fsdev/dcd_stm32_fsdev.c
@@ -275,7 +275,6 @@ static void handle_bus_reset(uint8_t rhport) {
 // Handle CTR interrupt for the TX/IN direction
 static void handle_ctr_tx(uint32_t ep_id) {
   uint32_t ep_reg = ep_read(ep_id) | USB_EP_CTR_TX | USB_EP_CTR_RX;
-  ep_reg &= USB_EPREG_MASK;
 
   uint8_t const ep_num = ep_reg & USB_EPADDR_FIELD;
   xfer_ctl_t *xfer = xfer_ctl_ptr(ep_num, TUSB_DIR_IN);
@@ -694,7 +693,6 @@ bool dcd_edpt_iso_activate(uint8_t rhport, tusb_desc_endpoint_t const *desc_ep)
 static void dcd_transmit_packet(xfer_ctl_t *xfer, uint16_t ep_ix) {
   uint16_t len = tu_min16(xfer->total_len - xfer->queued_len, xfer->max_packet_size);
   uint32_t ep_reg = ep_read(ep_ix) | USB_EP_CTR_TX | USB_EP_CTR_RX; // reserve CTR
-  ep_reg &= USB_EPREG_MASK | EP_STAT_MASK(TUSB_DIR_IN); // only change TX Status, reserve other toggle bits
 
   bool const is_iso = ep_is_iso(ep_reg);
 
@@ -719,6 +717,7 @@ static void dcd_transmit_packet(xfer_ctl_t *xfer, uint16_t ep_ix) {
   if (is_iso) {
     xfer->iso_in_sending = true;
   }
+  ep_reg &= USB_EPREG_MASK | EP_STAT_MASK(TUSB_DIR_IN); // only change TX Status, reserve other toggle bits
   ep_write(ep_ix, ep_reg, true);
 }