[alsa-devel] [PATCH] ASoC: ti: Allocate dais dynamically for TDM and audio graph card

[Tony Lindgren]

* Sebastian Reichel <sre at kernel.org> [200214 00:35]:
> On Wed, Feb 12, 2020 at 06:35:43AM -0800, Tony Lindgren wrote:
> > Yes this should follow the audio-graph-card.txt example. We end up with
> > mcbsp3 dts node as below on droid4:
> > 
> > &mcbsp3 {
> >         #sound-dai-cells = <0>;
> >         pinctrl-names = "default";
> >         pinctrl-0 = <&mcbsp3_pins>;
> >         status = "okay";
> > 
> >         ports {
> >                 mcbsp3_port: port at 0 {
> >                         #address-cells = <1>;
> >                         #size-cells = <0>;
> > 
> >                         cpu_dai3: endpoint at 0 {
> 
> cpu_dai3_cpcap
> 
> >                                 reg = <0>;
> >                                 dai-format = "dsp_a";
> >                                 frame-master = <&cpcap_audio_codec1>;
> >                                 bitclock-master = <&cpcap_audio_codec1>;
> >                                 remote-endpoint = <&cpcap_audio_codec1>;
> >                         };
> > 
> >                         cpu_dai_mdm: endpoint at 1 {
> 
> cpu_dai3_mdm

OK

> >                                 reg = <1>;
> >                                 dai-format = "dsp_a";
> >                                 frame-master = <&cpcap_audio_codec1>;
> >                                 bitclock-master = <&cpcap_audio_codec1>;
> >                                 remote-endpoint = <&mot_mdm6600_audio_codec0>;
> >                         };
> >                 };
> >         };
> > };
> > 
> > That is pretty much the same as the 'Multi DAI with DPCM' example, with
> > dne dai, and multiple endpoints. I think we still have just one port
> > for one i2s transport on the mcbsp :)
> > 
> > Does the above look as what you would expect based on the binding?
> 
> I haven't had a look at this for quite some time. I suppose the
> cpcap voice DAI and the modem will also have two endpoints? So
> once the BT support is added it will looks like this [simplified]?

Well it will be even simpler, no need for extra endpoints at
the codecs, see below.
 
> &mcbsp3 {
>     ports {
>         port at 0 {
>             cpu_dai3_cpcap: endpoint at 0 {};
>             cpu_dai3_modem: endpoint at 1 {};
>             cpu_dai3_bt: endpoint at 2 {};
>         };
>     };
> };

But yes, bluetooth would be just added as above under mcbsp3.

> &cpcap {
>     ports {
>         voice: port at 1 {
>             cpcap_voice_cpu: endpoint at 0 {};
>             cpcap_voice_modem: endpoint at 1 {};
>             cpcap_voice_bt: endpoint at 2 {};
>         };
>     };
> };

But above there's no need to add anything under cpcap, it still
only has the same two endpoints as it already has. So it's
just as specified in the graph binding, just the #address-cells,
#size-cells and reg added:

cpcap_audio: audio-codec {
	#sound-dai-cells = <1>;
	#address-cells = <1>;
	#size-cells = <0>;
	port at 0 {
		reg = <0>;
		cpcap_audio_codec0: endpoint {
		};
	};
	port at 1 {
		reg = <1>;
		cpcap_audio_codec1: endpoint {
		};
	};
};

Then the modem codec looks like this:

mot_mdm6600_audio: audio-codec {
	#address-cells = <1>;
	#size-cells = <0>;
	#sound-dai-cells = <1>;

	port at 0 {
		mot_mdm6600_audio_codec0: endpoint {
			remote-endpoint = <&cpu_dai_mdm>;
		};
	};
};

> &bluetooth {
>     ports {
>         port at 0 {
>             bt_dai_cpu: endpoint at 0 {};
>             bt_dai_modem: endpoint at 1 {};
>             bt_dai_cpcap: endpoint at 2 {};
>         };
>     };
> };

And bluetooth would be similar to cpcap_audio and mot_mdm6600_audio
above.

My guess is that only cpcap registers and clock rate needs to be
changed for bluetooth audio BTW, so if somebody havs a bluetooth
headset just do the following in Android:

# cpcaprw --all > /tmp/before
configure bluetooth headset for audio in android and start
playing some music or make a phone call
...
# cpcaprw --all > /tmp/after
stop playing music or phone call
...
diff -u /tmp/before /tmp/after

The registers will be different for a bluetooth phone call and
playing music.

> > > > I've tested this with droid4 where cpcap pmic and modem voice are both
> > > > both wired to mcbsp3. I've also tested this on droid4 both with and
> > > > without the pending modem audio codec driver that is waiting for n_gsm
> > > > serdev dependencies to clear.
> > > 
> > > What this patch you effectively just creating dummy-dais on top of the
> > > real McBSP DAI.
> > 
> > Yes I think this is needed for snd-soc-audio-graph-card, and this allows
> > configuring whatever is needed for the i2s slot. But maybe you have some
> > better way of doing it in mind?
> > 
> > > You also rename the DAIs, which might break ams-delta.
> > 
> > Oops, that's not good. So should we just keep the old naming if there's
> > only one endpoint?
> > 
> > > We still have legacy support in
> > > omap-twl4030.c
> > > omap3pandora.c
> > > osk5912.c
> > > rx51.c
> 
> also n810.c

OK

> > > which will break with the renamed DAI. On the other hand I think the
> > > legacy support can be dropped from them.
> > 
> > I'm not sure what all that would take.
> 
> rx51 and omap-twl4030 override the hardcoded paths with DT
> information when DT is available (= always), so hardcoded paths
> do not matter at all and could simply be removed (the patch
> should also make DT mandatory).
> 
> For omap3pandora, n810 and osk5912 the hardcoded information seems
> to be used and there does not seem to be any soundcard DT node for
> them. I suppose it's a bit of work for those devices. n810
> looks simple enough to just use simple-card.

OK I'll just keep the old naming if there's only one child node.

Regards,

Tony