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From: Takashi Iwai <tiwai@suse.de>
To: Mike Brady <mikebrady@eircom.net>
Cc: Stefan Wahren <stefan.wahren@i2se.com>,
	devel@driverdev.osuosl.org, alsa-devel@alsa-project.org,
	f.fainelli@gmail.com, julia.lawall@lip6.fr,
	gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org,
	eric@anholt.net, linux-rpi-kernel@lists.infradead.org,
	nishka.dasgupta_ug18@ashoka.edu.in,
	Kirill Marinushkin <k.marinushkin@gmail.com>,
	linux-arm-kernel@lists.infradead.org
Subject: Re: [alsa-devel] [PATCH v2] staging: bcm2835-audio: interpolate audio delay
Date: Mon, 05 Nov 2018 17:11:47 +0100	[thread overview]
Message-ID: <s5hsh0f1p30.wl-tiwai@suse.de> (raw)
In-Reply-To: <C35AD288-063F-4197-A758-450CBB3B1184@eircom.net>

On Mon, 05 Nov 2018 16:57:07 +0100,
Mike Brady wrote:
> 
> > One another thing I'd like to point out is that the value given in the
> > patch is nothing but an estimated position, optimistically calculated
> > via the system timer.  Mike and I had already discussion in another
> > thread, and another possible option would be to provide the proper
> > timestamp-vs-hwptr pair, instead of updating the timestamp always at
> > the status read.
> 
> Agreed — that would give the caller the information needed to do the
> interpolation for themselves if desired.

And now I wonder whether the problem is still present with the latest
code.  There was a (kind of) regression in this regard when we
introduced the fine-grained hardware timestamping, but it should have
been addressed by the commit 20e3f985bb875fea4f86b04eba4b6cc29bfd6b71
    ALSA: pcm: update tstamp only if audio_tstamp changed

Could you double-check whether the tstamp field gets still updated
even if no hwptr (and delay) is changed?


thanks,

Takashi

  reply	other threads:[~2018-11-05 16:11 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-10-18 10:57 [PATCH] staging: bcm2835-audio: interpolate audio delay Mike Brady
2018-10-18 11:02 ` Takashi Iwai
2018-10-18 19:48 ` Kirill Marinushkin
2018-10-22 19:08   ` Mike Brady
2018-10-22 19:17 ` [PATCH v2] " Mike Brady
2018-10-22 22:25   ` Kirill Marinushkin
2018-10-24  8:20     ` [alsa-devel] " Mike Brady
2018-10-24 18:06       ` Kirill Marinushkin
2018-10-24 19:54         ` Mike Brady
2018-10-24 22:02           ` Kirill Marinushkin
2018-10-25  7:37             ` Takashi Iwai
2018-10-25 17:20               ` Kirill Marinushkin
2018-10-28 14:24                 ` Mike Brady
2018-10-28 14:26               ` Mike Brady
2018-11-05 15:57                 ` Mike Brady
2018-11-05 16:11                   ` Takashi Iwai [this message]
2018-11-06 21:05                     ` Mike Brady
2018-11-06 21:31                       ` Takashi Iwai
2018-11-11 18:08                         ` Mike Brady
2018-11-11 18:21                           ` [PATCH v2] ARM: " Mike Brady
2018-11-11 20:18                           ` Stefan Wahren
2018-11-13 16:50                           ` Takashi Iwai
2019-01-01 10:02                             ` Mike Brady

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