On Mon, 27 Jan 2014, Peter Chen wrote:
> If the high-speed device does not enter full-speed idle after
> wakeup on disconnect logic has effected, there will be an
> unexpected disconnect wakeup interrupt due to the bus is still SE0.
I think you mean "If the high-speed device does not enter full-speed
idle _before_ wakeup on disconnect logic has taken effect..."
It sounds like this is a bug in your EHCI hardware. The
wake-on-disconnect logic should never take effect until after the port
goes into full-speed idle.
> Signed-off-by: Peter Chen <peter.chen@xxxxxxxxxxxxx>
> ---
>
> Changes for v2:
> Using usleep_range instead of mdelay
>
> drivers/usb/host/ehci-hub.c | 12 ++++++++++++
> 1 files changed, 12 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/usb/host/ehci-hub.c b/drivers/usb/host/ehci-hub.c
> index 47b858f..976294c 100644
> --- a/drivers/usb/host/ehci-hub.c
> +++ b/drivers/usb/host/ehci-hub.c
> @@ -301,6 +301,18 @@ static int ehci_bus_suspend (struct usb_hcd *hcd)
>
> if (t1 != t2) {
> ehci_writel(ehci, t2, reg);
> + if ((t2 & PORT_WKDISC_E)
> + && (ehci_port_speed(ehci, t2) ==
> + USB_PORT_STAT_HIGH_SPEED)) {
> + /*
> + * If the high-speed device has not switched
> + * to full-speed idle before WKDISC_E has
> + * effected, there will be a WKDISC event.
> + */
> + spin_unlock_irq(&ehci->lock);
> + usleep_range(3500, 4000);
> + spin_lock_irq(&ehci->lock);
> + }
This doesn't look like it will do what you want. t2 already has the
PORT_WKDISC_E bit set, so once the
ehci_writel(ehci, t2, reg);
has executed, it is already too late. Instead, you should write (t2 &
~PORT_WKDISC_E), then wait a few ms, and then write t2.
Since this bug seems to affect only a few EHCI controllers, we should
have a quirk flag for it. There's no need to make everybody wait 3.5-4
ms just for the sake of a few pieces of buggy hardware.
Alan Stern
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