[Qemu-devel] [PATCH] usb-hub: set PORT_STAT_C_SUSPEND on host-initiated wake-up

[Ladi Prosek]

PORT_STAT_C_SUSPEND should be set even on host-initiated wake-up,
i.e. on ClearPortFeature(PORT_SUSPEND). Windows is known to not
work properly otherwise.

Side note, since PORT_ENABLE looks similar and might appear to
have the same issue: According to 11.24.2.7.2.2 C_PORT_ENABLE:

  "This bit is set when the PORT_ENABLE bit changes from one to
  zero as a result of a Port Error condition (see Section 11.8.1).
  This bit is not set on any other changes to PORT_ENABLE."

Signed-off-by: Ladi Prosek <address@hidden>
---

One more usb-hub bug found with Windows guests. This one seems
to require input devices behind two levels of hubs to reproduce.
When one of the input devices remote-wakes up, Windows kicks the
other ones from suspend state using ClearPortFeature(PORT_SUSPEND).
Then it expects the change flag to be set by the hub.

 hw/usb/dev-hub.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/hw/usb/dev-hub.c b/hw/usb/dev-hub.c
index 47b7519..e82a6a6 100644
--- a/hw/usb/dev-hub.c
+++ b/hw/usb/dev-hub.c
@@ -402,7 +402,20 @@ static void usb_hub_handle_control(USBDevice *dev, 
USBPacket *p,
                 port->wPortChange &= ~PORT_STAT_C_ENABLE;
                 break;
             case PORT_SUSPEND:
-                port->wPortStatus &= ~PORT_STAT_SUSPEND;
+                if (port->wPortStatus & PORT_STAT_SUSPEND) {
+                    port->wPortStatus &= ~PORT_STAT_SUSPEND;
+
+                    /*
+                     * USB Spec rev2.0 11.24.2.7.2.3 C_PORT_SUSPEND
+                     * "This bit is set on the following transitions:
+                     *  - On transition from the Resuming state to the
+                     *    SendEOP [sic] state"
+                     *
+                     * Note that this includes both remote wake-up and
+                     * explicit ClearPortFeature(PORT_SUSPEND).
+                     */
+                    port->wPortChange |= PORT_STAT_C_SUSPEND;
+                }
                 break;
             case PORT_C_SUSPEND:
                 port->wPortChange &= ~PORT_STAT_C_SUSPEND;
-- 
2.9.3