Re: [Alsa-devel] Re: irq handler top half timestamps

[Florian Schmidt <mista.tapas@gmx.net>]

On Fri, 10 Dec 2004 08:52:39 +0100 (CET)
Jaroslav Kysela <perex@suse.cz> wrote:

> On Fri, 10 Dec 2004, Florian Schmidt wrote:
> 
> > So it would be very useful, if, for example, the top half irq handler of
> > the alsa driver would timestamp each IRQ with i.e. a TSC timestamp and
> > expose this timestamp to the application in userspace.
> 
> We can do any timestamp in the IRQ handler (this enum can be extended):
> 
> enum sndrv_pcm_tstamp {
>         SNDRV_PCM_TSTAMP_NONE = 0,
>         SNDRV_PCM_TSTAMP_MMAP,
>         SNDRV_PCM_TSTAMP_LAST = SNDRV_PCM_TSTAMP_MMAP,
> };
> 
> And this structure is used to store timestamp value:
> 
> struct timespec tstamp;

Way cool! But how to access it from userspace?

Flo

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http://affenbande.org/~tapas/


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