Re: [PATCH 04/15] V4L/DVB: ir-core: Add logic to decode IR protocols at the IR core

From: Mauro Carvalho Chehab <mchehab@redhat.com>
To: Andy Walls <awalls@md.metrocast.net>
Cc: linux-input@vger.kernel.org,
	Linux Media Mailing List <linux-media@vger.kernel.org>
Subject: Re: [PATCH 04/15] V4L/DVB: ir-core: Add logic to decode IR protocols at the IR core
Date: Fri, 02 Apr 2010 22:11:29 -0300	[thread overview]
Message-ID: <4BB695C1.3080208@redhat.com> (raw)
In-Reply-To: <1270256387.3027.84.camel@palomino.walls.org>

Andy Walls wrote:
> On Fri, 2010-04-02 at 19:39 -0400, Andy Walls wrote:
>> On Thu, 2010-04-01 at 14:56 -0300, Mauro Carvalho Chehab wrote:
> 
>>> +enum raw_event_type {
>>> +	IR_SPACE	= (1 << 0),
>>> +	IR_PULSE	= (1 << 1),
>>> +	IR_START_EVENT	= (1 << 2),
>>> +	IR_STOP_EVENT	= (1 << 3),
>>> +};
>>> +
>> Why are these events encoded as bit flags?  Shouldn't they all be
>> orthogonal?
>   ^^^^^^^^^^
> Argh, wrong word.

Why is it wrong? It seems appropriate to me.
> 
> Shouldn't they all be mutually exclusive?

space x pulse are mutually exclusive, and start x stop are also
mutually exclusive, but you may have several possible combinations
for an event. The hole set of possibilities are:

IR_SPACE
IR_PULSE
IR_SPACE | IR_START_EVENT
IR_SPACE | IR_STOP_EVENT
IR_PULSE | IR_START_EVENT
IR_PULSE | IR_STOP_EVENT

With bit flags, it is possible to cover all the above combinations.

In a matter of fact, the driver is currently not using the stop events.

-- 

Cheers,
Mauro