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usb: Don't allow USB_RET_ASYNC for interrupt packets

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It is tempting to use USB_RET_ASYNC for interrupt packets, rather then the
current NAK + polling approach, but this causes issues for migration, as
an async completed packet will not getting written back to guest memory until
the next poll time, and if a migration happens in between it will get lost!

Make an exception for host devices, because:
1) host-linux actually uses async completion for interrupt endpoints
2) host devices don't migrate anyways

Ideally we would convert host-linux.c to handle (input) interrupt endpoints in
a buffered manner like it does for isoc endpoints, keeping multiple urbs
submitted to ensure the devices timing requirements are met, as well as making
its interrupt ep handling the same as other usb-devices.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
This commit is contained in:
Hans de Goede 2012-11-17 12:47:15 +01:00 committed by Gerd Hoffmann
parent 8beba93043
commit be41efde3c
4 changed files with 7 additions and 0 deletions
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1
hw/usb.h
View File

@ -197,6 +197,7 @@ struct USBEndpoint {
enum USBDeviceFlags {
USB_DEV_FLAG_FULL_PATH,
USB_DEV_FLAG_IS_HOST,
};
/* definition of a USB device */

4
hw/usb/core.c
View File

@ -406,7 +406,11 @@ void usb_handle_packet(USBDevice *dev, USBPacket *p)
if (QTAILQ_EMPTY(&p->ep->queue) || p->ep->pipeline) {
usb_process_one(p);
if (p->status == USB_RET_ASYNC) {
/* hcd drivers cannot handle async for isoc */
assert(p->ep->type != USB_ENDPOINT_XFER_ISOC);
/* using async for interrupt packets breaks migration */
assert(p->ep->type != USB_ENDPOINT_XFER_INT ||
(dev->flags & USB_DEV_FLAG_IS_HOST));
usb_packet_set_state(p, USB_PACKET_ASYNC);
QTAILQ_INSERT_TAIL(&p->ep->queue, p, queue);
} else if (p->status == USB_RET_ADD_TO_QUEUE) {

1
hw/usb/host-bsd.c
View File

@ -292,6 +292,7 @@ static void usb_host_handle_destroy(USBDevice *opaque)
static int usb_host_initfn(USBDevice *dev)
{
dev->flags |= (1 << USB_DEV_FLAG_IS_HOST);
return 0;
}

1
hw/usb/host-linux.c
View File

@ -1476,6 +1476,7 @@ static int usb_host_initfn(USBDevice *dev)
{
USBHostDevice *s = DO_UPCAST(USBHostDevice, dev, dev);
dev->flags |= (1 << USB_DEV_FLAG_IS_HOST);
dev->auto_attach = 0;
s->fd = -1;
s->hub_fd = -1;