NEC 32 bits RC codes - was: Re: [PATCH 1/2] v180 - DM04/QQBOX added support for BS2F7HZ0194 versions

[Mauro Carvalho Chehab <mchehab@redhat.com>]

Em 23-03-2011 05:41, Antti Palosaari escreveu:
> On 03/23/2011 01:00 AM, Mauro Carvalho Chehab wrote:
>> Em 22-03-2011 19:12, Malcolm Priestley escreveu:
>>> On Tue, 2011-03-22 at 02:43 +0200, Antti Palosaari wrote:
> 
>>>> Anyhow, my opinion is still that we *should* make all NEC remotes as 32
>>>> bit and leave handling of NEC 16, NEC 24, NEC 32 to NEC decoder. For
>>>> example AF9015 current NEC handling is too complex for that reason... I
>>>> don't like how it is implemented currently.
>>>
>>> One of the reasons for using 32 bit was interference from other consumer
>>> remotes.  It appears, these near identical bubble remotes originate from
>>> a Chinese factory and supplied with the same product with completely
>>> different key mapping.
>>>
>>> I am not sure how many of these remotes are common to other devices.
>>
>> Drivers should get the 32 bit codes form NEC when hardware provides it.
>> What we currently do is to identify if the code has 16, 24 or 32 bits,
>> but it is probably better to always handle them as if they have 32 bits.
> 
> That's how af9015 driver handles it currently.
> 
> if (buf[14] == (u8) ~buf[15]) {
>     if (buf[12] == (u8) ~buf[13]) {
>         /* 16 bit NEC standard */
>         priv->rc_keycode = buf[12] << 8 | buf[14];
>     } else {
>         /* 24 bit NEC extended*/
>         priv->rc_keycode = buf[12] << 16 | buf[13] << 8 | buf[14];
>     }
> } else {
>     /* 32 bit NEC full scancode */
>     priv->rc_keycode = buf[12] << 24 | buf[13] << 16 | buf[14] << 8 | buf[15];
> }
> 
> I think there is no any better currently.

RC core does the same. I talked with Jarod, and we're thinking on just use 32 bits
for everything. There are two issues however:
	1) All NEC tables will need to be replaced. This affects userspace. Not sure
how to workaround it there, to allow userspace to do the right thing. New protocol type?
	2) Some hardware decoders only provide 16 bits for NEC.

Cheers,
Mauro