linux-kernel - Re: [PATCH v9 1/4] drm/i2c: tda998x: Add DT support for audio

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Message-ID: <20150107180825.52334d4f@armhf>
Date:	Wed, 7 Jan 2015 18:08:25 +0100
From:	Jean-Francois Moine <moinejf@...e.fr>
To:	Andrew Jackson <Andrew.Jackson@....com>
Cc:	Mark Brown <broonie@...nel.org>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	Dave Airlie <airlied@...il.com>, Jyri Sarha <jsarha@...com>,
	"alsa-devel@...a-project.org" <alsa-devel@...a-project.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"dri-devel@...ts.freedesktop.org" <dri-devel@...ts.freedesktop.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v9 1/4] drm/i2c: tda998x: Add DT support for audio

On Wed, 07 Jan 2015 14:39:13 +0000
Andrew Jackson <Andrew.Jackson@....com> wrote:

> > +  - audio-ports: must contain one or two values selecting the source
> > +	in the audio port.
> > +	The source type is given by the corresponding entry in
> > +	the audio-port-names property.  
> 
> I think that this entry might benefit from a little more explanation.
> The value specified here selects which pins on the chip provide the
> audio input doesn't it?  In the outline datasheet that I have these are
> listed in table 17:
> 
> Audio port 	Input configuration
> 		S/PDIF 		I2S-bus
> AP0 		- 		WS (word select)
> AP1 		S/PDIF input 	I2S-bus channel 0
> AP2 		S/PDIF input 	I2S-bus channel 1
> AP3[1] 				I2S-bus channel 2
> AP4[1] 				I2S-bus channel 3
> ACLK 		- 		SCK (I2S-bus clock)
> 
> [1] Depending on package.

Your table is close to the one in the TDA9983B documentation I have,
but the pins are not exactly the same:

AP0 		WS (word select)
AP1 		I2S-bus port 0
AP2 		I2S-bus port 1
AP3 		I2S-bus port 2
AP4 		I2S-bus port 3
AP5		MCLK (master clock for S/PDIF)
AP6		S/PDIF input
AP7		AUX (internal test)
ACLK 		SCK (I2S-bus clock)

That's why I did not know clearly why I had to set AP2 for S/PDIF input
and (AP0 + AP1) for I2S input in the Cubox.

Then, the only more explanation I could give is "have a look at the
audio input format and at the register 0x1e page 0 in the documentation
of the TDA998x chip".

BTW, the tda998x driver supports only the TDA9989, TDA19988 and
TDA19989 chips. If the TDA9983B would be supported, the audio port
definitions would be of no use.

So, what would you see as an explanation?

-- 
Ken ar c'hentañ	|	      ** Breizh ha Linux atav! **
Jef		|		http://moinejf.free.fr/
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