Hi Matthias,
On Fri, Apr 22, 2022 at 11:44:36AM -0700, Matthias Kaehlcke wrote:
> On Fri, Apr 22, 2022 at 01:57:17PM +0200, Rafael J. Wysocki wrote:
> > On Tue, Apr 19, 2022 at 9:11 PM Sandeep Maheswaram
> > <quic_c_sanm@xxxxxxxxxxx> wrote:
> > >
> > > From: Matthias Kaehlcke <mka@xxxxxxxxxxxx>
> > >
> > > Add device_children_wakeup_capable() which checks whether the device itself
> > > or one if its descendants is wakeup capable.
> >
> > device_wakeup_path() exists for a very similar purpose.
> >
> > Is it not usable for whatever you need the new function introduced here?
>
> I wasn't aware of it's function, there are no doc comments and the
> name isn't really self explanatory.
>
> In a quick test device_wakeup_path() returned inconsistent values for the
> root hub, sometimes true, others false when a wakeup capable USB device was
> connected.
We will also test the same to double confirm the behavior of
device_wakeup_path(). I am assuming that you checked device_wakeup_path()
only during system suspend path.
Here is what I understood by looking at __device_suspend(). Please share
your thoughts on this.
power.wakeup_path is set to true for the parent *after* a wakeup capable
device is suspended. This means when the root hub(s) is suspended, it is
propagated to xhci-plat and when xhci-plat is suspended, it is propagated
to dwc3. bottom up propgation during system suspend.
I believe we can directly check something like this in the dwc3 driver
instead of having another wrapper like device_children_wakeup_capable().
diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
index 1170b80..a783257 100644
--- a/drivers/usb/dwc3/core.c
+++ b/drivers/usb/dwc3/core.c
@@ -1878,8 +1878,14 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
break;
case DWC3_GCTL_PRTCAP_HOST:
if (!PMSG_IS_AUTO(msg)) {
+ /*
+ * Don't kill the host when dwc3 is wakeup capable and
+ * its children needs wakeup.
+ */
+ if (device_may_wakeup(dwc->dev) && device_wakeup_path(dwc->dev))
+ handle_it();
+ } else {
dwc3_core_exit(dwc);
- break;
}
/* Let controller to suspend HSPHY before PHY driver suspends */
Thanks,
Pavan
