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

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Message-ID: <CANLzEksV2kO6vXZJPbbs+oypb0LAetHZQAuB5RUjWVtsvMOrgw@mail.gmail.com>
Date:	Tue, 25 Nov 2014 07:29:16 -0800
From:	Benson Leung <bleung@...omium.org>
To:	Alan Stern <stern@...land.harvard.edu>
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 Tue, Nov 25, 2014 at 7:24 AM, Alan Stern <stern@...land.harvard.edu> wrote:
> 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.

Sure. I'll dig into this deeper today. I got to this late yesterday
and I ran out of time before I could find out what was not behaving
correctly.


>
> Alan Stern
>



-- 
Benson Leung
Software Engineer, Chrom* OS
bleung@...omium.org
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