[alsa-devel] Two codecs using the same I2S bus

Mark Brown broonie at opensource.wolfsonmicro.com
Mon Dec 14 11:33:03 CET 2009

On Sat, Dec 12, 2009 at 08:54:04PM +0100, Niels Langendorff wrote:
> Op 12 dec 2009, om 19:05 heeft Mark Brown het volgende geschreven:
> > On Fri, Dec 11, 2009 at 01:29:07PM +0100, Niels Langendorff wrote:

> > This should work with the kernel as-is providing the two CODECs don't
> > both need register control, just declare DAI links for each of the links
> > you need from your machine driver.  

> Both the codecs needs to be reconfigured by writing the registers for
> every playback/recording, so that is the difficulty.

I see.  The difficulty with more than one register based device is
somewhat orthogonal to the DAIs.  The current approach to such systems
is to have a driver for one of the devices which provides functions
which can be called from the machine drivers - the MAX9877 and TPA6130A2
in mainline are examples.  This doesn't scale so well, though it is
workable for the time being if the devices aren't too complex.

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