From: Grazvydas Ignotas <notasas@gmail.com>
To: Mark Brown <broonie@opensource.wolfsonmicro.com>
Cc: Peter Ujfalusi <peter.ujfalusi@ti.com>,
alsa-devel@alsa-project.org, Liam Girdwood <lrg@ti.com>,
Jarkko Nikula <jarkko.nikula@bitmer.com>
Subject: Re: [PATCH 3/3] ASoC: omap-mcbsp: Add period size protection mode
Date: Tue, 20 Mar 2012 18:15:34 +0200 [thread overview]
Message-ID: <CANOLnOPjqbeEbSDUHokkGRUa7KwJ-+hAczWSmQ3LEccCh9-c7w@mail.gmail.com> (raw)
In-Reply-To: <20120320160154.GI3445@opensource.wolfsonmicro.com>
On Tue, Mar 20, 2012 at 6:01 PM, Mark Brown
<broonie@opensource.wolfsonmicro.com> wrote:
> On Tue, Mar 20, 2012 at 01:13:41PM +0200, Peter Ujfalusi wrote:
>> Certain application can experience underrun right after the playback start.
>> This is caused by the McBSP FIFO/sDMA integration:
>> The sDMA will push samples to the FIFO till it has threshold amount of free
>> slots available in the FIFO. If the application picks period size which is
>> smaller than the FIFO size, and it did not prepared multiple periods, or
>> it did not set the start_threshold for the stream to cover the FIFO size
>> the hw pointer will move forward, which is causing the underrun.
>
> Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
>
> though this should probably have the note about working around broken
> applications from the cover letter in the changelog as with the
> changelog alone it's really not apparent why we're doing this here as a
> driver specific thing.
I wouldn't really call them broken, it's enough to set period size to
512 with smaller start_threshold (something like 50ms) to have
problems, those parameters are perfectly valid for a program trying to
achieve low latency.
It's a shame this still won't work out-of-the box, but at least there
will be some solution.
--
Gražvydas
_______________________________________________
Alsa-devel mailing list
Alsa-devel@alsa-project.org
http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
next prev parent reply other threads:[~2012-03-20 16:15 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-20 11:13 [PATCH 0/3] ASoC: omap-mcbsp: Constraint handling changes Peter Ujfalusi
2012-03-20 11:13 ` [PATCH 1/3] ASoC: omap-mcbsp: buffer size constraint only applies to playback stream Peter Ujfalusi
2012-03-20 15:26 ` Mark Brown
2012-03-20 16:34 ` Jarkko Nikula
2012-03-20 11:13 ` [PATCH 2/3] ASoC: omap-mcbsp: Restructure omap_mcbsp_dai_startup code Peter Ujfalusi
2012-03-20 15:27 ` Mark Brown
2012-03-20 11:13 ` [PATCH 3/3] ASoC: omap-mcbsp: Add period size protection mode Peter Ujfalusi
2012-03-20 16:01 ` Mark Brown
2012-03-20 16:15 ` Grazvydas Ignotas [this message]
2012-03-20 17:04 ` Mark Brown
2012-03-20 17:27 ` Grazvydas Ignotas
2012-03-20 18:07 ` Trent Piepho
2012-03-20 18:12 ` Mark Brown
2012-03-21 8:23 ` Peter Ujfalusi
2012-03-21 11:55 ` Grazvydas Ignotas
2012-03-20 16:20 ` Jarkko Nikula
2012-03-20 16:42 ` Grazvydas Ignotas
2012-03-20 19:20 ` Jarkko Nikula
2012-03-20 19:47 ` Trent Piepho
2012-03-21 7:57 ` Peter Ujfalusi
2012-03-21 8:13 ` Jarkko Nikula
2012-03-21 8:21 ` Peter Ujfalusi
2012-03-21 8:03 ` Peter Ujfalusi
2012-03-21 8:32 ` Jarkko Nikula
2012-03-21 8:40 ` Mark Brown
2012-03-21 9:16 ` Peter Ujfalusi
2012-03-21 9:34 ` Jarkko Nikula
2012-03-21 9:46 ` Peter Ujfalusi
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CANOLnOPjqbeEbSDUHokkGRUa7KwJ-+hAczWSmQ3LEccCh9-c7w@mail.gmail.com \
--to=notasas@gmail.com \
--cc=alsa-devel@alsa-project.org \
--cc=broonie@opensource.wolfsonmicro.com \
--cc=jarkko.nikula@bitmer.com \
--cc=lrg@ti.com \
--cc=peter.ujfalusi@ti.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).