Re: [PATCH][resend] rc: gpio-ir-recv: allow flush space on idle

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Thanks again Sean,

On 09/14/2015 07:54 AM, Sean Young wrote:
> On Mon, Sep 14, 2015 at 07:34:10AM -0700, Eric Nelson wrote:
>> Thanks Shawn,
>>
>> On 09/14/2015 03:00 AM, Sean Young wrote:
>>> On Fri, Sep 11, 2015 at 07:00:24AM -0700, Eric Nelson wrote:
>>>> Many decoders require a trailing space (period without IR illumination)
>>>> to be delivered before completing a decode.
>>>>
>>>> Since the gpio-ir-recv driver only delivers events on gpio transitions,
>>>> a single IR symbol (caused by a quick touch on an IR remote) will not
>>>> be properly decoded without the use of a timer to flush the tail end
>>>> state of the IR receiver.
>>>
>>> This is a problem other IR drivers suffer from too. It might be better
>>> to send a IR timeout event like st_rc_send_lirc_timeout() in st_rc.c,
>>> with the duration set to what the timeout was. That is what irraw 
>>> timeouts are for; much better than fake transitions.
>>>
>>
>> If I'm understanding this correctly, this would require modification
>> of each decoder to handle what seems to be a special case regarding
>> the GPIO IR driver (which needs an edge to trigger an interrupt).
> 
> No, this is not a special case. Many drivers do have extra code to generate
> some sort of end-of-signal message: redrat3; igorplugusb; st_rc. They don't
> handle it consistently but this should be fixed.
> 
> Secondly, the decoders already handle it. A timeout event matches 
> is_timing_event(), so it's processed by the decoders. The duration should 
> be set correctly.
> 

I think I did misunderstand you.

You're suggesting that I re-work the patch to gpio-ir-recv.c to
produce a timeout instead of an edge. Is that right?

>> Isn't it better to have the device interface handle this in one place?
> 
>>>> This patch adds an optional device tree node "flush-ms" which, if
>>>> present, will use a jiffie-based timer to complete the last pulse
>>>> stream and allow decode.
>>>
>>> A common value for this is 100ms, I'm not sure what use it has to have
>>> it configurable. It's nice to have it exposed in rc_dev->timeout.
>>>
>>
>> I'm enough of a n00b regarding the details of the various decoders
>> not to know that...
>>
>> I looked through the couple of decoders my customer was using (NEC and
>> RC6) and came up with a value of 100ms though...
>>
>> Implementing this through DT and having the default as 0 (disabled)
>> provides an interim solution if the choice is made to change each of
>> the decoders, since I would expect that to take a while and a bunch of
>> remote control devices for testing.
> 
> Many other drivers use 100ms just fine and I don't remember ever seeing
> any bug reports on that.
> 

So you'd like to see this as a constant?

Please advise,


Eric

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