From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ingo Molnar <mingo@elte.hu>
Subject: Re: [Alsa-devel] Re: irq handler top half timestamps
Date: Thu, 16 Dec 2004 10:18:12 +0100
Message-ID: <20041216091812.GE11047@elte.hu>
References: <200412102051.iBAKphFL012668@localhost.localdomain> <1102712509.29919.46.camel@krustophenia.net> <20041211015610.1798af34@mango.fruits.de> <20041211032214.5121a003@mango.fruits.de> <20041216003255.6e65360b@mango.fruits.de>
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To: Florian Schmidt <mista.tapas@gmx.net>
Cc: Lee Revell <rlrevell@joe-job.com>, Paul Davis <paul@linuxaudiosystems.com>, Jaroslav Kysela <perex@suse.cz>, jackit-devel@lists.sourceforge.net, alsa-devel <alsa-devel@lists.sourceforge.net>
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* Florian Schmidt <mista.tapas@gmx.net> wrote:

> On Sat, 11 Dec 2004 03:22:14 +0100
> Florian Schmidt <mista.tapas@gmx.net> wrote:
> 
> > Oh, i almost forgot: Ingo has already posted a patch adding this to the
> > threaded irq handlers in recent RP kernels. ALSA could access it. But
> > making ALSA depend on a kernel feature of an experimental kernel might
> > be unwise (uneducated guess). 
> > 
> > Also this leaves the question of using a different timer source for the
> > timestamps in the case that TSC is unreliable open.
> > 
> > Is it sensible to require users of jackd to not use cpu freq scaling
> > during operation? If so, we could just settle on using the TSC.
> > 
> > Flo
> > 
> 
> is
> 
> snd_pcm_get_trigger_tstamp()
> 
> the api call to get the timestamp of the irq handler?
> 
> flo

in case you want to add it to ALSA within the -RT patchset, -RT now has
a generic function:

 extern cycles_t irq_timestamp(unsigned int irq);

the timestamps do get generated for every irq.

(but ... the usual disclaimer: this is just a playground thing, so
there's no guarantee of upstream merging.)

	Ingo


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