linux-kernel - Re: [RFC v2] Another approach to IR

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Date:	Wed, 2 Dec 2009 15:57:38 -0500
From:	Jarod Wilson <jarod@...sonet.com>
To:	Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc:	Jarod Wilson <jarod@...hat.com>, Jon Smirl <jonsmirl@...il.com>,
	Mauro Carvalho Chehab <mchehab@...hat.com>,
	Devin Heitmueller <dheitmueller@...nellabs.com>,
	Maxim Levitsky <maximlevitsky@...il.com>, awalls@...ix.net,
	j@...nau.net, khc@...waw.pl, linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
	lirc-list@...ts.sourceforge.net, superm1@...ntu.com,
	Christoph Bartelmus <lirc@...telmus.de>
Subject: Re: [RFC v2] Another approach to IR

On Dec 2, 2009, at 3:48 PM, Dmitry Torokhov wrote:
...
>>>>>> Personally, I've always considered the driver/interface to be the  
>>>>>> receiver, not the remote. The lirc drivers operate at the receiver  
>>>>>> level, anyway, and the distinction between different remotes is made by  
>>>>>> the lirc daemon.
>>>>> 
>>>>> The fact that lirc does it this way does not necessarily mean it is the
>>>>> most corerct way.
>>>> 
>>>> No, I know that, I'm just saying that's how I've always looked at it, and that's how lirc does it right now, not that it must be that way.
>>>> 
>>>>> Do you expect all bluetooth input devices be presented
>>>>> as a single blob just because they happen to talk to the sane receiver
>>>>> in yoru laptop? Do you expect your USB mouse and keyboard be merged
>>>>> together just because they end up being serviced by the same host
>>>>> controller? If not why remotes should be any different?
>>>> 
>>>> A bluetooth remote has a specific device ID that the receiver has to
>>>> pair with. Your usb mouse and keyboard each have specific device IDs.
>>>> A usb IR *receiver* has a specific device ID, the remotes do not. So
>>>> there's the major difference from your examples.
>>>> 
>>> 
>>> Not exactly... I can have 2 identical USB keyboadrs form the same
>>> manufacturer and they will still be treated separately. BT has session
>>> ID to help distinguish between devices.
>> 
>> Semantics. :)
>> 
>> My main point is that each of these devices has device ID that can be determined without having to first do some protocol analysis and table lookups to figure out which "device" some random IR input is actually coming from.
>> 
> 
> Heh, right back at ya ;) The fact that you need to do some more work
> to separate 2 physical devices does not mean it should not be done.

No, but it means added complexity inside the kernel. I'm questioning whether the added complexity is worth it, when I doubt the vast majority of users would take advantage of it, and it can already be done in userspace. Although... Damn. The userspace approach would only work if the device were passing raw IR to userspace, so in the in-kernel decoding case, yeah, I guess you'd need separate input devices for each remote to use them independently. Meh. Doubt I'd ever use it, but I guess I'll concede that it makes some sense to do the extra work.

-- 
Jarod Wilson
jarod@...sonet.com



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