On Thu, Apr 08, 2010 at 02:10:40AM -0300, Mauro Carvalho Chehab wrote:
> David Härdeman wrote:
> >
> > o The RX decoding is now handled via a workqueue (I can break that up into a
> > separate patch later, but I think it helps the discussion to have it in for
> > now), with inspiration from Andy's code.
>
> I'm in doubt about that. the workqueue is called just after an event. this means
> that, just after every IRQ trigger (assuming the worse case), the workqueue will
> be called.
No
> On the previous code, it is drivers responsibility to call the function that
> de-queue. On saa7134, I've scheduled it to wake after 15 ms. So, instead of
> 32 wakeups, just one is done, and the additional delay introduced by it is not
> enough to disturb the user.
It's still the case with my patch, the ir_raw_event_handle() function is
still there and it will call schedule_work().
>> o int's are still used to represent pulse/space durations in ms.
>> Mauro and I seem to disagree on this one but I'm right :)
>
> :)
>
> We both have different opinions on that. I didn't hear a good argument from you
> why your're right and I am wrong ;)
>
> Maybe we can try to make a deal on it.
>
> What you're really doing is:
>
> struct rc_event {
> u32 mark : 1;
> u32 duration :31; /* in microsseconds */
> };
>
> Please, correct me if I'm wrong, but I suspect that the technical reasons behind your
> proposal are:
> 1) to save space at kfifo and argument exchange with the functions;
> 2) nanoseconds is too short for a carrier at the order of 10^4
> Hz;
>
> My proposal is to do something like:
>
> struct rc_event {
> enum rc_event_type type;
> u64 duration /* in nanoseconds */
>
> My rationale are:
> 1) To make the decoder code less obfuscated;
Subjective
> 2) To use the same time measurement as used on kernel timers, avoiding an uneeded division
> for IRQ and polling-based devices.
Are you sure you don't want to rewrite ir_raw_event_store_edge() and
ir_raw_event_store() in assembly?
>
> It might have some other non-technical issues, like foo/bar uses this/that, this means less changes
> on some code, etc, but we shouldn't consider those non-technical issues when discussing
> the architecture.
>
> So, here's the deal:
>
>
> Let's do something in-between. While I still think that using a different measure for
> duration will add an unnecessary runtime conversion from kernel ktime into
> microsseconds, for me, the most important point is to avoid obfuscating the code.
>
> So, we can define a opaque type:
>
> typedef u32 mark_duration_t;
>
> To represent the rc_event struct (this isn't a number anymore - it is a struct with one
> bit for mark/space and 31 bits for unsigned duration). The use of an opaque type may
> avoid people to do common mistakes.
I've seldom seen a case where a "typedef gobbledygook" is considered
clearer than a native data type.
> And use some macros to convert from this type, like:
>
> #define DURATION(mark_duration) abs(mark_duration)
> #define MARK(duration) (abs(duration))
> #define SPACE(duration) (-abs(duration))
> #define IS_MARK(mark_duration) ((duration > 0) ? 1 : 0)
> #define IS_SPACE(mark_duration) ((duration < 0) ? 1 : 0)
> #define DURATION(mark_duration) abs(mark_duration)
> #define TO_UNITS(mark_duration, unit) \
> do { \
> a = DIV_ROUND_CLOSEST(DURATION(mark_duration), unit); \
> a = (mark_duration < 0) ? -a: a; \
> } while (0)
>
> And use it along the decoders:
If you think a couple of defines would make it that much clearer, I can
add some defines. If the division in ktime_us_delta() worries you that
much, I can avoid it as well.
So how about:
s64 duration; /* signed to represent pulse/space, in ns */
This is the return value from ktime subtraction, so no conversion
necessary. Then I'll also add defines along your lines.
New patch coming up...
--
David Härdeman
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