From: Mark Brown <broonie@opensource.wolfsonmicro.com>
To: Scott Jiang <scott.jiang.linux@gmail.com>
Cc: alsa-devel@alsa-project.org
Subject: Re: ASoC: how to calculate dma size in tdm mode
Date: Thu, 9 Aug 2012 11:38:14 +0100 [thread overview]
Message-ID: <20120809103812.GJ24328@opensource.wolfsonmicro.com> (raw)
In-Reply-To: <CAHG8p1Am-FcJ0CO9Mo-Wc1-i=LHrX1-46rVe4w9nXyCs7iD10w@mail.gmail.com>
On Thu, Aug 09, 2012 at 05:56:57PM +0800, Scott Jiang wrote:
> If user app use 2 channels but codec need 8 channels in tdm mode, I
> need to copy this data from user space to dma buffer. I wonder how to
> calculate dma size, snd_pcm_hardware.buffer_bytes_max or
> buffer_bytes_max * tdm_channels / channels_min?
I'm not sure which data you mean here? It sounds like your hardware
doesn't support stereo DMA, if that's the case your capabilites should
reflect it. With most hardware you'd just do a normal stereo playback
here, the unused TDM timeslots would not be visible outside of the DAI.
next prev parent reply other threads:[~2012-08-09 10:08 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-09 9:56 ASoC: how to calculate dma size in tdm mode Scott Jiang
2012-08-09 10:38 ` Mark Brown [this message]
2012-08-10 2:46 ` Scott Jiang
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