From: Mark Brown <broonie@kernel.org>
To: Maxime Ripard <maxime.ripard@bootlin.com>
Cc: alsa-devel@alsa-project.org,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Takashi Iwai <tiwai@suse.com>,
Liam Girdwood <lgirdwood@gmail.com>, Chen-Yu Tsai <wens@csie.org>,
Thomas Petazzoni <thomas.petazzoni@bootlin.com>,
Jaroslav Kysela <perex@perex.cz>,
linux-arm-kernel@lists.infradead.org
Subject: Re: Best representation for TDM devices
Date: Thu, 25 Jul 2019 18:44:09 +0100 [thread overview]
Message-ID: <20190725174409.GF4213@sirena.org.uk> (raw)
In-Reply-To: <20190725130112.3j2vi4dyngyr6yh3@flea>
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On Thu, Jul 25, 2019 at 03:01:12PM +0200, Maxime Ripard wrote:
> Since I have two codecs, I have two links (described through
> simple-card) and thus two subdevices. However, the microphones
> connected are really separate streams, so ideally (I guess?) we should
> have 1 subdevice per microphone.
> An alternative would be that we capture the whole 4 channels and use
> dsnoop to demux them, but trying to use the device directly (using
> arecord -D hw:0) results in the ioctl to change the number of channels
> being rejected, I'm assuming because each codec only has 2 channels?
> So I'm a bit lost at this point about how I should go and expose
> this. I couldn't really find any similar setup either in the
> kernel. Any preferred way of doing this?
What is the actual hardware - what do the microphones physically look
like in the system, what functional role do they play? My initial guess
would be to combine them into a single PCM for userspace, there's some
support for that but it's not surprising if that's broken somewhere
along the line as it's very infrequently tested.
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next prev parent reply other threads:[~2019-07-25 17:44 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-25 13:01 Best representation for TDM devices Maxime Ripard
2019-07-25 17:44 ` Mark Brown [this message]
[not found] <CAMTEBE0mPY=44txPC2G+Cb=NqeH6Cqesar9Vkq0afXBv4dUWHQ@mail.gmail.com>
2019-08-01 11:48 ` Mark Brown
2019-08-14 10:53 ` Ali Burak Parım
2019-08-14 16:02 ` Mark Brown
2019-08-19 8:41 ` Maxime Ripard
2019-08-19 15:45 ` Mark Brown
2019-08-20 14:06 ` Maxime Ripard
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