how to link up audio bus from media controller driver to soc dai bus?

how to link up audio bus from media controller driver to soc dai bus?

[Tim Harvey]

Greetings,

I'm working on a media controller driver for the tda1997x HDMI
receiver which provides an audio bus supporting I2S/SPDIF/OBA/HBR/DST.
I'm unclear how to bind the audio bus to a SoC's audio bus, for
example the IMX6 SSI (I2S) bus. I thought perhaps it was via a
simple-audio-card device-tree binding but that appears to require an
ALSA codec to bind to?

Can anyone point me to an example of a media controller device driver
that supports audio and video and how the audio is bound to a I2S bus?

Regards,

Tim

Re: how to link up audio bus from media controller driver to soc dai bus?

[Alex Deucher]

On Mon, Jun 12, 2017 at 3:15 PM, Tim Harvey <tharvey@gateworks.com> wrote:
> Greetings,
>
> I'm working on a media controller driver for the tda1997x HDMI
> receiver which provides an audio bus supporting I2S/SPDIF/OBA/HBR/DST.
> I'm unclear how to bind the audio bus to a SoC's audio bus, for
> example the IMX6 SSI (I2S) bus. I thought perhaps it was via a
> simple-audio-card device-tree binding but that appears to require an
> ALSA codec to bind to?
>
> Can anyone point me to an example of a media controller device driver
> that supports audio and video and how the audio is bound to a I2S bus?

I'm not sure if this is what you are looking for now not, but on some
AMD APUs, we have an i2s bus and codec attached to the GPU rather than
as a standalone device.  The audio DMA engine and interrupts are
controlled via the GPU's mmio aperture, but we expose the audio DMA
engine and i2c interface via alsa.  We use the MFD (Multi-Function
Device) kernel infrastructure to do this.  The GPU driver loads and
probes the audio capabilities and triggers the hotplug of the i2s and
audio dma engine.

For the GPU side see:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/gpu/drm/amd/amdgpu/amdgpu_acp.c
for the audio side:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/sound/soc/amd/acp-pcm-dma.c

Alex

Re: how to link up audio bus from media controller driver to soc dai bus?

[Fabio Estevam]

Hi Tim,

On Mon, Jun 12, 2017 at 4:15 PM, Tim Harvey <tharvey@gateworks.com> wrote:
> Greetings,
>
> I'm working on a media controller driver for the tda1997x HDMI
> receiver which provides an audio bus supporting I2S/SPDIF/OBA/HBR/DST.
> I'm unclear how to bind the audio bus to a SoC's audio bus, for
> example the IMX6 SSI (I2S) bus. I thought perhaps it was via a
> simple-audio-card device-tree binding but that appears to require an
> ALSA codec to bind to?
>
> Can anyone point me to an example of a media controller device driver
> that supports audio and video and how the audio is bound to a I2S bus?

Does the tda998x.txt example help?

Documentation/devicetree/bindings/display/bridge/tda998x.txt

and the dts example:

arch/arm/boot/dts/am335x-boneblack-common.dtsi