linux-kernel - Re: [RFC] What are the goals for the architecture of an in-kernel IR system?

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Date:	Fri, 9 Apr 2010 09:02:09 -0400
From:	Jon Smirl <jonsmirl@...il.com>
To:	Jarod Wilson <jarod@...hat.com>
Cc:	Andy Walls <awalls@...ix.net>, James Hogan <james@...anarts.com>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Pavel Machek <pavel@....cz>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	Krzysztof Halasa <khc@...waw.pl>,
	hermann pitton <hermann-pitton@...or.de>,
	Christoph Bartelmus <lirc@...telmus.de>, j@...nau.net,
	jarod@...sonet.com, kraxel@...hat.com, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	superm1@...ntu.com
Subject: Re: [RFC] What are the goals for the architecture of an in-kernel IR 
	system?

On Fri, Apr 9, 2010 at 8:58 AM, Jarod Wilson <jarod@...hat.com> wrote:
> On Fri, Apr 09, 2010 at 06:50:26AM -0400, Andy Walls wrote:
>> On Fri, 2010-04-09 at 08:21 +0100, James Hogan wrote:
>> > Hi,
>> >
>> > On Thursday 25 March 2010 14:42:33 Mauro Carvalho Chehab wrote:
>> > > Comments?
>> >
>> > I haven't seen this mentioned yet, but are there any plans for a sysfs
>> > interface to set up waking from suspend/standby on a particular IR scancode
>> > (for hardware decoders that support masking of comparing of the IR data), kind
>> > of analagous to the rtc framework's wakealarm sysfs file?
>>
>> This requires support at the hardware level.  (You can't have CPU code
>> running to decode IR pulses when your CPU is "asleep".)
>>
>> I know of two video chips supported under linux that provide such a
>> function.
>>
>> Wake-up from IR for these chips will rely on the kernel PCIe or USB
>> infrastructure supporting PCIe or USB Power Managment Events from
>> hardware.  It will take a huge amount of work and time to get the
>> respective linux video drivers to properly support suspend/resume
>> properly.
>>
>> If you're waiting for me to get that working, I'll advise you to plan on
>> getting off the couch and pushing the power switch for some time to
>> come. ;)
>>
>>
>>
>>
>> The MCE-USB, I *speculate*, can perform wakes.  It's driver would need
>> to support that, if it can.
>
> Yep, it can perform wakes, and the current lirc_mceusb does support it,
> though it requires some screwing around with echoing something into
> somewhere in sysfs (for the usb controller its attached to) to enable it,

You probably need to tell the USB system to leave the MSMCE's power
turned on during suspend. Maybe the MSMCE driver can tell the USB
subsystem to leave it powered across suspend when the driver loads.

> from what I recall... Making it Just Work would be a good idea.
>
> --
> Jarod Wilson
> jarod@...hat.com
>
>



-- 
Jon Smirl
jonsmirl@...il.com
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