linux-kernel - Re: [PATCH v3 2/2] [media] uvcvideo: Remain runtime-suspended at sleeps

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Message-ID: <CAAObsKCP4dTvOPB=XrZexauHmdC99JYkc6cYKoaT-vZjnLaynw@mail.gmail.com>
Date:	Mon, 20 Apr 2015 09:11:36 +0200
From:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
To:	Alan Stern <stern@...land.harvard.edu>
Cc:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Laurent Pinchart <laurent.pinchart@...asonboard.com>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Mauro Carvalho Chehab <mchehab@....samsung.com>,
	linux-media@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v3 2/2] [media] uvcvideo: Remain runtime-suspended at sleeps

On 17 April 2015 at 19:32, Alan Stern <stern@...land.harvard.edu> wrote:
> On Fri, 17 Apr 2015, Tomeu Vizoso wrote:
>
>> When the system goes to sleep and afterwards resumes, a significant
>> amount of time is spent suspending and resuming devices that were
>> already runtime-suspended.
>>
>> By setting the power.force_direct_complete flag, the PM core will ignore
>> the state of descendant devices and the device will be let in
>> runtime-suspend.
>>
>> Signed-off-by: Tomeu Vizoso <tomeu.vizoso@...labora.com>
>> ---
>>  drivers/media/usb/uvc/uvc_driver.c | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
>> index 5970dd6..ae75a70 100644
>> --- a/drivers/media/usb/uvc/uvc_driver.c
>> +++ b/drivers/media/usb/uvc/uvc_driver.c
>> @@ -1945,6 +1945,8 @@ static int uvc_probe(struct usb_interface *intf,
>>                       "supported.\n", ret);
>>       }
>>
>> +     intf->dev.parent->power.force_direct_complete = true;
>
> This seems wrong.  The uvc driver is bound to intf, not to intf's
> parent.  So it would be okay for the driver to set
> intf->dev.power.force_direct_complete, but it's wrong to set
> intf->dev.parent->power.force_direct_complete.

Agreed.

Thanks,

Tomeu

> Alan Stern
>
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