On Thu, 27 Sep 2012, Ming Lei wrote:
> From: Ming Lei <tom.leiming@xxxxxxxxx>
>
> The hub status endpoint has a long 'bInterval', which is 255ms
> for FS/LS device and 256ms for HS device according to USB 2.0 spec,
> so the device connection change may be reported later more than 255ms
> via status pipe.
>
> The connection change in hub may have been happened already on the
> downstream ports, but no status URB completes when it is killed
> in hub_suspend(auto), so the connection change may be missed by some
> buggy hub devices, which won't generate remote wakeup signal after
> their remote wakeup is enabled and they are put into suspend state.
>
> The problem can be observed at least on the below Genesys Logic, Inc.
> hub devices:
>
> 0x05e3,0x0606
> 0x05e3,0x0608
>
> In theory, there is no way to fix the problem completely, but we
> can make it less likely to occur by this patch.
>
> This patch introduces one quirk of HUB_QUIRK_CHECK_PORTS_AUTOSUSPEND
> to check ports' change during hub_suspend(auto) for the buggy
> devices. If ports' change is found, terminate the auto suspend and
> return to working state.
>
> So for the buggy hubs, if the connection change happend before
> the ports' check, it can be handled correctly. If it happens between
> the ports' check and enabling remote wakeup/entering suspend, it
> will be missed. Considered the interval is quite short, it is very
> less likely to happen during the window.
One remark and one tiny problem...
> @@ -3176,6 +3198,17 @@ static int hub_suspend(struct usb_interface *intf, pm_message_t msg)
> return -EBUSY;
> }
> }
> +
> + if (hdev->do_remote_wakeup && hub->quirk_check_port_auto_suspend) {
> + /* check if there are changes pending on hub ports */
> + if (check_ports_changed(hub)) {
> + if (!PMSG_IS_AUTO(msg) &&
> + device_may_wakeup(&hdev->dev))
You don't need to check device_may_wakeup(); the core has already taken
care of it. If device_may_wakeup() returns 0 then do_remote_wakeup
will be 0 also.
> + pm_wakeup_event(&hdev->dev, 2000);
> + return -EBUSY;
> + }
> + }
The !PMSG_IS_AUTO case should not return -EBUSY, because
usb_suspend_both() will ignore the return value. It should proceed
with the rest of the suspend.
Alan Stern
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