usb: fix port reset

commit 891fb2cd4592b6fe76106a69e0ca40efbf82726a removed the implicit
detach before (re-)attaching in usb_attach().  Some usb host controllers
used that behavior though to do a port reset by a detach+attach
sequence.

This patch establishes old behavior by adding a new usb_reset() function
for port resets and putting it into use, thereby also unifying port
reset behavior of all host controllers.  The patch also adds asserts to
usb_attach() and usb_detach() to make sure the calls are symmetrical.

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

1 files changed, 12 insertions, 0 deletions

diff --git a/hw/usb.c b/hw/usb.c
index fa90204c5..2216efe07 100644
--- a/hw/usb.c
+++ b/hw/usb.c
@@ -33,6 +33,7 @@ void usb_attach(USBPort *port)
 
     assert(dev != NULL);
     assert(dev->attached);
+    assert(dev->state == USB_STATE_NOTATTACHED);
     port->ops->attach(port);
     usb_send_msg(dev, USB_MSG_ATTACH);
 }
@@ -42,10 +43,21 @@ void usb_detach(USBPort *port)
     USBDevice *dev = port->dev;
 
     assert(dev != NULL);
+    assert(dev->state != USB_STATE_NOTATTACHED);
     port->ops->detach(port);
     usb_send_msg(dev, USB_MSG_DETACH);
 }
 
+void usb_reset(USBPort *port)
+{
+    USBDevice *dev = port->dev;
+
+    assert(dev != NULL);
+    usb_detach(port);
+    usb_attach(port);
+    usb_send_msg(dev, USB_MSG_RESET);
+}
+
 void usb_wakeup(USBDevice *dev)
 {
     if (dev->remote_wakeup && dev->port && dev->port->ops->wakeup) {