From: Marc Gonzalez <marc.w.gonzalez@free.fr>
To: alsa-devel@alsa-project.org
Cc: Takashi Iwai <tiwai@suse.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
Jaroslav Kysela <perex@perex.cz>
Subject: Re: Propagating audio properties along the audio path
Date: Mon, 23 Sep 2019 12:47:33 +0200 [thread overview]
Message-ID: <878168cb-07e0-cdfd-37e9-9b9fb229155b@free.fr> (raw)
In-Reply-To: <d67b68b9-49c0-6f78-4649-27b3b437a65f@free.fr>
On 20/09/2019 11:50, Marc Gonzalez wrote:
> One more concern popped up: if the audio stream changes mid-capture
> (for example, a different TV program uses different audio settings),
> then I would detect this in the eARC receiver, but it's not clear
> (to me) how to propagate the info to the DSP...
>
> I'm not even sure when the HW params actually get applied...
> Is it for SNDRV_PCM_IOCTL_PREPARE? SNDRV_PCM_IOCTL_START?
I enabled debug logs in the sound layer:
echo "file sound/* +fpm" > /sys/kernel/debug/dynamic_debug/control
and sprinkled dump_stack() in several driver callbacks.
When I run 'tinycap /tmp/earc.wav -t 10 -r 44100 -b 32'
I see the open/SyS_openat call and the capture ioctl call
which together generate calls to
1) dpcm_fe_dai_open
2) dpcm_fe_dai_hw_params
3) dpcm_fe_dai_prepare
4) dpcm_fe_dai_trigger
But everything looks "synchronous", as in "reaction to user-space commands".
I don't see how "asynchronous" events are dealt with, such as the stream
params changing while a capture is active?
Regards.
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2019-09-23 10:47 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-17 15:33 Propagating audio properties along the audio path Marc Gonzalez
2019-09-20 9:50 ` Marc Gonzalez
2019-09-23 10:47 ` Marc Gonzalez [this message]
2019-09-24 13:52 ` [alsa-devel] " Charles Keepax
2019-09-24 14:26 ` Marc Gonzalez
2019-09-24 14:42 ` Charles Keepax
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=878168cb-07e0-cdfd-37e9-9b9fb229155b@free.fr \
--to=marc.w.gonzalez@free.fr \
--cc=alsa-devel@alsa-project.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=perex@perex.cz \
--cc=tiwai@suse.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