On Mon, 27 Dec 2010, Sarah Sharp wrote:
> When there's an xHCI host power loss after a suspend from memory, the USB
> core attempts to reset and verify the USB devices that are attached to the
> system. The xHCI driver has to reallocate those devices, since the
> hardware lost all knowledge of them during the power loss.
>
> When a hub is plugged in, and the host loses power, the xHCI hardware
> structures are not updated to say the device is a hub. This is usually
> done in hub_configure() when the USB hub is detected. That function is
> skipped during a reset and verify by the USB core, since the core restores
> the old configuration and alternate settings, and the hub driver has no
> idea this happened. This bug makes the xHCI host controller reject the
> enumeration of low speed devices under the resumed hub.
>
> Therefore, make the USB core re-setup the internal xHCI hub device
> information by calling update_hub_device() when hub_activate() is called
> for a hub reset resume. After a host power loss, all devices under the
> roothub get a reset-resume or a disconnect.
>
> Signed-off-by: Sarah Sharp <sarah.a.sharp@xxxxxxxxxxxxxxx>
> ---
>
> Alan,
>
> Is calling hub_port_logical_disconnect() if the xHCI driver can't
> configure the hub structures correctly the right thing to do? At that
> point, any low speed device plugged into the hub probably isn't going to
> work, and I suspect any new children hubs won't work either.
You'd lose all the devices already plugged into the hub. I suggest
logging a dev_err message and continuing in a "degraded" mode.
> @@ -715,6 +717,23 @@ static void hub_activate(struct usb_hub *hub, enum hub_activation_type type)
> usb_autopm_get_interface_no_resume(
> to_usb_interface(hub->intfdev));
> return; /* Continues at init2: below */
> + } else if (type == HUB_RESET_RESUME) {
> + /* The internal host controller state for the hub device
> + * may be gone after a host power loss on system resume.
> + * Update the device's info so the HW knows it's a hub.
> + */
> + hcd = bus_to_hcd(hdev->bus);
> + if (hcd->driver->update_hub_device) {
> + ret = hcd->driver->update_hub_device(hcd, hdev,
> + &hub->tt, GFP_KERNEL);
Isn't this supposed to be GFP_NOIO?
Alan Stern
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