usb: host: ohci-platform: Implement ohci_platform_shutdown

[Tony Lindgren <tony@atomide.com>]

* Alan Stern <stern@rowland.harvard.edu> [190322 20:03]:
> On Fri, 22 Mar 2019, Tony Lindgren wrote:
> 
> > * Alan Stern <stern@rowland.harvard.edu> [190322 18:37]:
> > > How about putting these runtime PM additions into
> > > usb_hcd_platform_shutdown instead, so they will apply to all platform
> > > controller drivers?
> > 
> > OK let's do that then.
> > 
> > > Also, are you certain you want the pm_runtime_put_sync at the end?  If 
> > > the system is shutting down anyway, why waste time doing an extra 
> > > runtime suspend?
> > 
> > Well mostly to keep the calls paired. But maybe there are
> > also kexec reboot cases where we'd want to have things
> > properly disabled for PM before kexec.
> 
> I'm not sure that makes sense.  You can't actually disable anything for 
> runtime PM from within a driver; all you can do is tell the runtime PM 
> core that _you're_ not using the device any more.  But if some other 
> part of the system is still using it, it will remain at full power.

Right, it's just a usecount and whatever happens after that is
ouf of the driver control. And in the shutdown case PM runtime
does not have much of a chance to do anything here :)

Not much point checking the pm_runtime_get_sync() for errors
either then.. We can just add a comment there.

If the patch below looks OK to you I'll post with an updated
description.

Regards,

Tony

8< -------------------

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -3017,6 +3017,9 @@ usb_hcd_platform_shutdown(struct platform_device *dev)
 {
 	struct usb_hcd *hcd = platform_get_drvdata(dev);
 
+	/* No need for pm_runtime_put(), we're shutting down */
+	pm_runtime_get_sync(&dev->dev);
+
 	if (hcd->driver->shutdown)
 		hcd->driver->shutdown(hcd);
 }