From: Jarkko Nikula <jhnikula@gmail.com>
To: ext-eero.nurkkala@nokia.com
Cc: "tiwai@suse.de" <tiwai@suse.de>,
"alsa-devel@alsa-project.org" <alsa-devel@alsa-project.org>,
"broonie@opensource.wolfsonmicro.com"
<broonie@opensource.wolfsonmicro.com>,
"Ujfalusi Peter (Nokia-D/Tampere)" <peter.ujfalusi@nokia.com>,
"lrg@slimlogic.co.uk" <lrg@slimlogic.co.uk>
Subject: Re: [RFC 3/4] OMAP3: McBSP: Add interface for transmit FIFO state query
Date: Wed, 3 Mar 2010 09:03:24 +0200 [thread overview]
Message-ID: <20100303090324.83d076b6.jhnikula@gmail.com> (raw)
In-Reply-To: <1267596472.24345.16.camel@eenurkka-desktop>
On Wed, 03 Mar 2010 08:07:52 +0200
Eero Nurkkala <ext-eero.nurkkala@nokia.com> wrote:
> Mostly the samples were good (49/50, @48khz, 2 channels, value polled
> from userpace), but the remaining 1/50 were garbage - and actually
> matched the probability of a simultaneous DMA burst. So the problem is -
> if you read at time t0, and the DMA burst is taking place at the same
> time - you get a value that looks rather random, as when (if) you poll
> the position @ t0 + n uS, the value is (after some usecs) a lot
> different. Or maybe the XBUFFSTAT just isn't reliable at all (regardless
> of DMA bursts etc).
>
Yeah, that's interesting to find out are the XBUFFSTAT reading
differences inside the DMA burst size or distributed completely
randomly. I think the XBUFFSTAT should increase at the sample rate and
decrease or jump down fast when the DMA burst takes place.
--
Jarkko
next prev parent reply other threads:[~2010-03-03 7:02 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-03-02 13:39 [RFC 0/4] FIFO caused playback delay (latency) handling in soc Peter Ujfalusi
2010-03-02 13:39 ` [RFC 1/4] ASoC: core: soc level wrapper for pcm_pointer callback Peter Ujfalusi
2010-03-02 13:39 ` [RFC 2/4] ASoC: core: Add delay operation to snd_soc_dai_ops Peter Ujfalusi
2010-03-02 13:45 ` Mark Brown
2010-03-02 13:49 ` Peter Ujfalusi
2010-03-02 13:54 ` Mark Brown
2010-03-02 13:39 ` [RFC 3/4] OMAP3: McBSP: Add interface for transmit FIFO state query Peter Ujfalusi
2010-03-02 13:45 ` Mark Brown
2010-03-02 13:52 ` Eero Nurkkala
2010-03-02 13:58 ` Liam Girdwood
2010-03-02 14:02 ` Peter Ujfalusi
2010-03-02 14:06 ` Jarkko Nikula
2010-03-03 6:07 ` Eero Nurkkala
2010-03-03 7:03 ` Jarkko Nikula [this message]
2010-03-03 10:02 ` Peter Ujfalusi
2010-03-03 10:07 ` Peter Ujfalusi
2010-03-03 14:18 ` Jarkko Nikula
2010-03-03 15:01 ` Peter Ujfalusi
2010-03-04 7:30 ` Peter Ujfalusi
2010-03-03 19:00 ` ext-Eero.Nurkkala
2010-03-03 19:07 ` ext-Eero.Nurkkala
2010-03-04 7:53 ` Peter Ujfalusi
2010-03-04 8:09 ` Peter Ujfalusi
2010-03-04 8:46 ` Eero Nurkkala
2010-03-02 13:39 ` [RFC 4/4] ASoC: OMAP3: Report delay on playback caused by the internal FIFO Peter Ujfalusi
2010-03-02 13:47 ` Mark Brown
2010-03-02 13:52 ` Peter Ujfalusi
2010-03-02 14:06 ` Mark Brown
2010-03-02 13:53 ` [RFC 0/4] FIFO caused playback delay (latency) handling in soc Mark Brown
2010-03-02 23:29 ` Raymond Yau
2010-03-03 10:03 ` Mark Brown
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