Register Alsa ASOC wm8782 driver

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1

Hello people, i’m trying to interface the Wolfson wm8782 ADC with my BB Black.
My first approach was modify the file davinci-evm.c, so the kernel will load the wm8782 driver instead of the tdax998 (used for hdmi).
The first problem that i’m facing is that i dont know exactly where apply these changes, so far i see two options:

here:

`

case MACHINE_VERSION_3:
evm_dai.name = “NXP TDA HDMI Chip”;
evm_dai.stream_name = “HDMI”;
evm_dai.codec_dai_name = “wm8782-hifi”;
evm_dai.init = evm_tda998x_init;

`

or here:

`

static struct snd_soc_dai_link da830_evm_dai = {
.name = “wm8782”,
.stream_name = “Capture”,
.cpu_dai_name = “davinci-mcasp.0”,
.codec_dai_name = “wm8782-hifi”,
.codec_name = “wm8782-codec.0-0018”,
.platform_name = “davinci-mcasp.0”,
.init = evm_aic3x_init,
.ops = &evm_ops,

`

I think that the code in the first option only gets executed when the dtbo file “cape-boneblack-hdmi” is loaded (is this correct?),
but neither of these options seems to work…

The only “solution” that i came up with was replacing the code of the tda998x.c with the code of wm8782.c driver, but i don’t
think this is the right way…

The files that i think would do the trick are: davinci-evm.c, wm8782.c and board-am3517evm.c but, obvioulsy, i’m not sure of this…
I’m also trying to document all these steps so anyone can interface an adc/dac to the BBB.

Any help will be appreciated,
Thanks in advance!

2

Hello people, i'm trying to interface the Wolfson wm8782 ADC with my BB
Black.
My first approach was modify the file davinci-evm.c, so the kernel will
load the wm8782 driver instead of the tdax998 (used for hdmi).
The first problem that i'm facing is that i dont know exactly where apply
these changes, so far i see two options:

here:

case MACHINE_VERSION_3:
evm_dai.name = "NXP TDA HDMI Chip";
evm_dai.stream_name = "HDMI";
evm_dai.codec_dai_name = "wm8782-hifi";
evm_dai.init = evm_tda998x_init;

or here:

static struct snd_soc_dai_link da830_evm_dai = {
.name = "wm8782",
.stream_name = "Capture",
.cpu_dai_name = "davinci-mcasp.0",
.codec_dai_name = "wm8782-hifi",
.codec_name = "wm8782-codec.0-0018",
.platform_name = "davinci-mcasp.0",
.init = evm_aic3x_init,
.ops = &evm_ops,

This portion is for a different platform - notice the struct name is
'da830_evm_dai'.

If it's just the codec change then setting the right codec_name and
ensuring the appropriate driver
is compiled in should have been sufficient.

I think that the code in the first option only gets executed when the dtbo

file "cape-boneblack-hdmi" is loaded (is this correct?),
but neither of these options seems to work...

The only "solution" that i came up with was replacing the code of the
tda998x.c with the code of wm8782.c driver, but i don't
think this is the right way...

Yeah it's not :slight_smile:

The files that i think would do the trick are: *davinci-evm.c*, *wm8782.c*and
*board-am3517evm.c* but, obvioulsy, i'm not sure of this...

The board file (board-am3517evm.c) is for yet another platform which is not
relevant here.
You should be looking at the device tree files now.

I *think* the codec driver won't need any change. You might have to make
some changes in davinci-evm.c though.
The last time i checked there were patches on the ALSA mailing list to have
most of the configuration coming via appropriate DT-bindings. I don't know
what kernel you are running but hopefully the above is enough for you to
start
looking around.

3

Thanks Vaibhav for answering,
So the files that i should edit are davinci-evm.c (platform driver?) and wm8782.c (codec driver), right?

I have a few questions :slight_smile:

What snd_soc_dai_link structure should i edit?
(I choosed the da830_dai_link because that was the snd_soc_card struct loaded when the BB Audio cape was inserted, but which one should i edit?)
I also tried to write a new davinci-evm.c based on this file (from a kernel source for the raspberry pi), here is the code:

`

/*

  • ASoC Driver.