[linux-dvb] Ticlkess Mantis remote control implementation

Marko Ristola marko.ristola at kolumbus.fi
Wed Jun 25 22:22:33 CEST 2008

Roland Scheidegger wrote:
> On 24.06.2008 21:50, Marko Ristola wrote:
>> Hi,
>> I have still my own version of Manu's jusst.de/mantis driver that is 
>> based on v4l-dvb-linuxtv main branch,
>> mainly because I use so new Linux kernels.
>> I have done the following improvement lately:
>> I implemented a remote control patch, that doesn't poll the remote 
>> control all the time.
>> It polls the remote control only if you press the button (a tickless 
>> version, you know).
>> It surprised me, that the actual implementation was really small, it 
>> took very few lines of code.
> You're not the first to think that the constant polling is not
> necessary, too bad these things always get lost because they aren't
> integrated in the official driver...
> http://www.linuxtv.org/pipermail/linux-dvb/2008-May/026102.html
Okay, I understood from your patch that you just deliver all key repeats 
as initial key presses.
You have disabled the polling altogether, but just deliver the key 
presses as initial key presses
and deliver the "key unpressed" instantly after the key press.
What is the feeling? I think that it might work for my remote control 
Also I noticed that you mentioned that you remote control's initial key 
repeat comes after 270ms.
So polling on my code should be done with 300ms intervals for example.
Maybe it would make my own remote control also more robust.

My version is better only in the sense that some application would be 
able to
catch the fact that the user is pressing a button and holding it down a 
long time. Maybe some programs need that for robustness.

Your version is better in the sense that you repeat 270ms and 220ms 
rerepeats correctly, as the remote control sends them.

Can we implement a version that has both advantages and is still 
acceptable to the kernel?

+ no work cancellation needs to be done during normal operation.
+ no current time calculation is done.

With both features working, it could be done in the following way:
Set a work with a timeout of 300ms.
Deliver all key presses and repeats instantly.
On key press delivery, cancel the assumed ealier delayed check and setup 
a new checking work with 300ms delay.
If a 300ms checking delay will be ever active, it will just inform "no 
key pressed" and continue.

On my opinion this "final" implementation might be a generic 
implementation which could be used in more places than on Mantis driver.

One question is, that are these Mantis remote controls at all like RC5 
remote controls mentioned in ir-common.c/h.
If yes, the correct way might be to use it's implementation.

Personally I haven't seen a "key unpressed" IRQ with my remote.
That event seems to be needed, if RC5 code is going to be used.

It might though be, that the interrupt line for "key unpressed" isn't 
the same as with "key pressed".
That might be rather easy to investigate and the implementation for "key 
unpressed" would be then trivial.

So currently using RC5 implementation on ir-common.c doesn't seem to be 
easy if at all possible.

> Roland

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