Messages in this thread | | | Date | Sun, 4 Sep 2005 17:34:45 -0700 | From | Nish Aravamudan <> | Subject | Re: [DVB patch 51/54] ttpci: av7110: RC5+ remote control support |
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On 9/4/05, Johannes Stezenbach <js@linuxtv.org> wrote: > On Sun, Sep 04, 2005 Nish Aravamudan wrote: > > On 9/4/05, Johannes Stezenbach <js@linuxtv.org> wrote: > > > On Sun, Sep 04, 2005 Nish Aravamudan wrote: > > > > On 9/4/05, Johannes Stezenbach <js@linuxtv.org> wrote: > > > > > > > > > > -#define UP_TIMEOUT (HZ/4) > > > > > +#define UP_TIMEOUT (HZ*7/25) > > > > > > > > #define UP_TIMEOUT msecs_to_jiffies(280) > > > > #define UP_TIMEOUT (7*msecs_to_jiffies(40) > > > > > > I agree it's nicer to read, but AFAIK not required for correctness? > > > If so, then we'll fix those up in linuxtv.org CVS and submit > > > cleanup patches later. > > > > Yeah, it's correct with the three current values of HZ (100, 250 and > > 1000), but if you try a not-so-clean value (like Con did with 864, or > > something), you might run into rounding issues. msecs_to_jiffies() > > should take care of them (or will be a single point to do so > > eventually). > > Well, if msecs_to_jiffies() is the new way of specifying timeouts > we'd have a lot more to fix up in our tree. But something like > a remote control key-up timeout doesn't need much precision. > Generally I see nothing wrong with HZ/4, but something like > HZ*20/1000 could be problematic with small or odd HZ values.
This discussion comes up every time ;) HZ/4 rounds incorrectly (depends on your perspective, I guess) with HZ=250.
> Agreed? Or is it desired that people generally use msecs_to_jiffies()?
I agree, generally it's ok, as timeouts aren't meant to be precise. I, personally, am converting code over to msecs_to_jiffies() as I come to it, just so that the conversions are consistent (a number in the tree were not, not that yours are) and basically self-commented. And, like I mentioned, they are automatically rounded correctly with "strange" values of HZ.
The changes I mentioned in your patchset are generally not critical, but just comments and my own preferences.
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