uhci: use bottom half

Schedule bottom half on completion of async packets instead of calling
uhci_process_frame directly.  This way we run uhci_process_frame only
once in case multiple packets finish in a row.  Also check whenever
there is bandwidth left before scheduling uhci_process_frame.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

hw/usb/hcd-uhci.c

@@ -131,6 +131,7 @@ struct UHCIState {
     uint8_t status2; /* bit 0 and 1 are used to generate UHCI_STS_USBINT */
     int64_t expire_time;
     QEMUTimer *frame_timer;
+    QEMUBH *bh;
     uint32_t frame_bytes;
     UHCIPort ports[NB_PORTS];
 
@@ -370,6 +371,7 @@ static void uhci_reset(void *opaque)
     }
 
     uhci_async_cancel_all(s);
+    qemu_bh_cancel(s->bh);
     uhci_update_irq(s);
 }
 
@@ -906,7 +908,9 @@ static void uhci_async_complete(USBPort *port, USBPacket *packet)
         uhci_async_free(async);
     } else {
         async->done = 1;
-        uhci_process_frame(s);
+        if (s->frame_bytes < 1280) {
+            qemu_bh_schedule(s->bh);
+        }
     }
 }
 
@@ -1113,6 +1117,12 @@ out:
     s->pending_int_mask |= int_mask;
 }
 
+static void uhci_bh(void *opaque)
+{
+    UHCIState *s = opaque;
+    uhci_process_frame(s);
+}
+
 static void uhci_frame_timer(void *opaque)
 {
     UHCIState *s = opaque;
@@ -1120,6 +1130,7 @@ static void uhci_frame_timer(void *opaque)
     /* prepare the timer for the next frame */
     s->expire_time += (get_ticks_per_sec() / FRAME_TIMER_FREQ);
     s->frame_bytes = 0;
+    qemu_bh_cancel(s->bh);
 
     if (!(s->cmd & UHCI_CMD_RS)) {
         /* Full stop */
@@ -1206,6 +1217,7 @@ static int usb_uhci_common_initfn(PCIDevice *dev)
                               USB_SPEED_MASK_LOW | USB_SPEED_MASK_FULL);
         }
     }
+    s->bh = qemu_bh_new(uhci_bh, s);
     s->frame_timer = qemu_new_timer_ns(vm_clock, uhci_frame_timer, s);
     s->num_ports_vmstate = NB_PORTS;
     QTAILQ_INIT(&s->queues);