usb: device_next: limit CDC ACM OUT transfer size to the current MPS

When the controller is connected to a full speed bus, regardless of whether the controller supports high speed or not, the transfer size for the bulk OUT endpoint should be equal to the MPS in the current configuration. Signed-off-by: Johann Fischer <[email protected]>
zephyrproject-rtos · Oct 2, 2024 · 3304357 · 3304357
1 parent 98ba81c
commit 3304357
Showing 1 changed file with 3 additions and 0 deletions.
diff --git a/subsys/usb/device_next/class/usbd_cdc_acm.c b/subsys/usb/device_next/class/usbd_cdc_acm.c
@@ -596,6 +596,9 @@ static void cdc_acm_rx_fifo_handler(struct k_work *work)
 		return;
 	}
 
+	/* Shrink the buffer size if operating on a full speed bus */
+	buf->size = MIN(cdc_acm_get_bulk_mps(c_data), buf->size);
+
 	ret = usbd_ep_enqueue(c_data, buf);
 	if (ret) {
 		LOG_ERR("Failed to enqueue net_buf for 0x%02x", ep);