* that's better aligned for the user.
         */
        hd->buffer_headroom = sizeof(u32);      /* For cport id */
-       hd->buffer_size_max = ES1_GBUF_MSG_SIZE_MAX;
+       hd->buffer_size_max = ES1_GBUF_MSG_SIZE_MAX - hd->buffer_headroom;
        BUILD_BUG_ON(hd->buffer_headroom > GB_BUFFER_HEADROOM_MAX);
 }
 
                pr_err("request to send inbound data buffer\n");
                return ERR_PTR(-EINVAL);
        }
-       if (cport_id > (u16)U8_MAX) {
+       if (cport_id > U8_MAX) {
                pr_err("cport_id (%hd) is out of range for ES1\n", cport_id);
                return ERR_PTR(-EINVAL);
        }
         * the rest of the stream is "real" data
         */
        data = urb->transfer_buffer;
-       cport_id = (u16)data[0];
+       cport_id = data[0];
        data = &data[1];
 
        /* Pass this data to the greybus core */
        free_urb(es1, urb);
 }
 
-static void apb1_log_get(struct es1_ap_dev *es1)
+#define APB1_LOG_MSG_SIZE      64
+static void apb1_log_get(struct es1_ap_dev *es1, char *buf)
 {
-       char buf[65];
        int retval;
 
        /* SVC messages go down our control pipe */
        do {
-               memset(buf, 0, 65);
                retval = usb_control_msg(es1->usb_dev,
                                        usb_rcvctrlpipe(es1->usb_dev,
                                                        es1->control_endpoint),
                                        USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_INTERFACE,
                                        0x00, 0x00,
                                        buf,
-                                       64,
+                                       APB1_LOG_MSG_SIZE,
                                        ES1_TIMEOUT);
                if (retval > 0)
                        kfifo_in(&apb1_log_fifo, buf, retval);
 
 static int apb1_log_poll(void *data)
 {
+       struct es1_ap_dev *es1 = data;
+       char *buf;
+
+       buf = kmalloc(APB1_LOG_MSG_SIZE, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
        while (!kthread_should_stop()) {
                msleep(1000);
-               apb1_log_get((struct es1_ap_dev *)data);
+               apb1_log_get(es1, buf);
        }
+
+       kfree(buf);
+
        return 0;
 }