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

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Message-ID: <20100409125832.GA22814@redhat.com>
Date:	Fri, 9 Apr 2010 08:58:32 -0400
From:	Jarod Wilson <jarod@...hat.com>
To:	Andy Walls <awalls@...ix.net>
Cc:	James Hogan <james@...anarts.com>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Jon Smirl <jonsmirl@...il.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 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,
from what I recall... Making it Just Work would be a good idea.

-- 
Jarod Wilson
jarod@...hat.com

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