Re: [Qemu-devel] [PATCH 29/37] ehci: kick async schedule on wakeup

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 06/07/2012 11:31 AM, Gerd Hoffmann wrote:
> Kick async schedule when we get a wakeup
> notification from a usb device.
>
> Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
> ---
>   hw/usb/hcd-ehci.c |    2 ++
>   1 files changed, 2 insertions(+), 0 deletions(-)
>
> diff --git a/hw/usb/hcd-ehci.c b/hw/usb/hcd-ehci.c
> index 8b2dfed..f8ed80d 100644
> --- a/hw/usb/hcd-ehci.c
> +++ b/hw/usb/hcd-ehci.c
> @@ -852,6 +852,8 @@ static void ehci_wakeup(USBPort *port)
>           USBPort *companion = s->companion_ports[port->index];
>           if (companion->ops->wakeup) {
>               companion->ops->wakeup(companion);
> +        } else {
> +            qemu_bh_schedule(s->async_bh);
>           }
>       }
>   }
>

This is wrong, this puts the added else inside the
"if (portsc & PORTSC_POWNER) {" block, iow it will only
trigger when the port is redirected to the companion controller,
it should be the else of the "if (portsc & PORTSC_POWNER)" so that
the async schedule gets kicked on wakeup when the device is connected
to the ehci (rather then to an companion uhci).

Notice how the if where the else now belongs to is unconditionally
dereferencing companion in the form of companion->ops, it can do
this because the "if (portsc & PORTSC_POWNER)" check ensures there is
a companion port for this device, the second level if is to see if
the companion has wakeup support.

Regards,

Hans