On Fri, Feb 21, 2014 at 10:45 AM, Mathias Nyman
<mathias.nyman@xxxxxxxxxxxxxxx> wrote:
>>> @@ -4753,6 +4753,8 @@ int xhci_gen_setup(struct usb_hcd *hcd,
>>> xhci_get_quirks_t get_quirks)
>>> * companion controller.
>>> */
>>> hcd->has_tt = 1;
>>> + /* prevent USB2 runtime pm until USB3 parts are
>>> initialized */
>>> + pm_runtime_get_noresume(hcd->self.controller);
>>> } else {
>>> /* xHCI private pointer was set in xhci_pci_probe for
>>> the second
>>> * registered roothub.
>>> @@ -4765,6 +4767,9 @@ int xhci_gen_setup(struct usb_hcd *hcd,
>>> xhci_get_quirks_t get_quirks)
>>> if (xhci->hci_version < 0x100)
>>> hcd->self.no_sg_constraint = 1;
>>>
>>> + /* USB3 initialized far enough to allow runtime pm
>>> suspend */
>>> + pm_runtime_put_noidle(hcd->self.controller);
>>> +
>>
>>
>> Why the noresume and noidle versions? Shouldn't these be the _sync
>> versions?
>>
>
> As I understood it the _sync versions may actually run pm_runtime_resume /
> pm_runtime_idle. Which is not what I'm looking for here.
>
> Noresume and noidle will just increase / decrease the usage count and that
> way prevent usb2 roothub register from calling xhci_suspend.
>
> This is how I gather it works:
>
> Round 1: add usb2 hcd
>
> usb_add_hcd() // primary usb2 hcd
> hcd->self.root_hub = usb_alloc_dev()
> hcd->driver->reset(hcd) -> xhci_gen_setup()
> if(primary_hcd) // true
> pm_runtime_get_noresume(hcd->self.controller) // +1 usage
> register_root_hub(hcd) -> usb_new_device(usb_dev)
> pm_runtime_set_active(&udev->dev);
> pm_runtime_get_noresume(&udev->dev);
> pm_runtime_use_autosuspend(&udev->dev);
> pm_runtime_enable(&udev->dev);
> ...
> pm_runtime_put_sync_autosuspend(&udev->dev); this would trigger
> xhci_suspend if all usages were 0. (for both roothub and controller)
> which oopses as usb3 stuff is not yet initialized
>
> Round 2: add usb 3 hcd
>
> usb_add_hcd() // secondary usb3 hcd
> hcd->self.root_hub = usb_alloc_dev()
> hcd->driver->reset(hcd) -> xhci_gen_setup()
> if(primary_hcd) // false
> ..
> else
> pm_runtime_put_noidle(hcd->self.controller) // -1 usage, *
> register_root_hub(hcd) -> usb_new_device(usb_dev)
> pm_runtime_set_active(&udev->dev);
> pm_runtime_get_noresume(&udev->dev);
> pm_runtime_use_autosuspend(&udev->dev);
> pm_runtime_enable(&udev->dev);
> ...
> pm_runtime_put_sync_autosuspend(&udev->dev); // ok to trigger would
> trigger xhci_suspend if all usages were 0.
>
> *) unnecessary to trigger any suspend as we're just about to register the
> usb3 roothub. but we need to decrement the usage counter.
Right, but I assume you'd want to hold the reference until after the
hub is registered, otherwise there's still a chance we suspend right
before register. So I'm saying hold the reference until the
registration process takes its own.
--
To unsubscribe from this list: send the line "unsubscribe linux-usb" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
