linux-kernel - Re: [PATCH] HID: usbhid: get/put around clearing needs_remote

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Message-ID: <Pine.LNX.4.44L0.1411251022141.976-100000@iolanthe.rowland.org>
Date:	Tue, 25 Nov 2014 10:24:25 -0500 (EST)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Benson Leung <bleung@...omium.org>
cc:	johan@...nel.org, Jiri Kosina <jkosina@...e.cz>,
	<linux-usb@...r.kernel.org>,
	"linux-input@...r.kernel.org" <linux-input@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Sameer Nanda <snanda@...omium.org>
Subject: Re: [PATCH] HID: usbhid: get/put around clearing needs_remote_wakeup

On Mon, 24 Nov 2014, Benson Leung wrote:

> Hi Alan,
> 
> 
> On Sat, Nov 22, 2014 at 7:55 AM, Alan Stern <stern@...land.harvard.edu> wrote:
> > There is no USB wrapper for pm_runtime_idle calls, but one could be
> > added.  Still, in the meantime can you check to see what happens if you
> > add
> >
> >         pm_runtime_idle(&usbhid->intf->dev);
> >
> > in usbhid_close() just after needs_remote_wakeup is set to 0?  You can
> > do the same thing in usbhid_stop() if you want.
> 
> I tried using this in lieu of usb_autopm_get/put_interface:
> 
>     usbhid->intf->needs_remote_wakeup = 0;
>     pm_runtime_idle(&usbhid->intf->dev);
>     pm_runtime_idle(usbhid->intf->dev.parent);
> 
> It did not work. I see the autosuspend_check() that was kicked off as
> a result of hid_hw_power, which falls into the "remote wakeup needed
> for autosuspend" branch, but I don't see another autosuspend_check()
> that picks up the updated value of  needs_remote_wakeup.

Well, why not?

In order to work on the kernel effectively, you need the right 
mind-set.  Don't just tell people when something goes wrong -- figure 
out why the problem occurred and propose a way to fix it.

Alan Stern

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