[v3,2/4] ASoC: add fsl_audmix DT binding documentation

Commit Message

Viorel Suman Jan. 17, 2019, 12:46 p.m. UTC

Add the DT binding documentation for NXP Audio Mixer
CPU DAI driver.

Signed-off-by: Viorel Suman <[e-mail]>
---
 .../devicetree/bindings/sound/fsl,audmix.txt       | 50 ++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/sound/fsl,audmix.txt

Comments

Nicolin Chen Jan. 26, 2019, 1:49 a.m. UTC | #1

On Thu, Jan 17, 2019 at 12:46:29PM +0000, Viorel Suman wrote:

> +  - dais		: Must contain a list of phandles to AUDMIX connected
> +			  DAIs. The current implementation requires two phandles
> +			  to SAI interfaces to be provided, the first SAI in the
> +			  list being used to route the AUDMIX output.

Another small thing, that I just noticed, is this list. It forces
the first input source to be the output source without giving any
chance. I feel that we could have some flexibility here: one node
for two input sources, and one node for the output source.

Well, there is no critical problem with the current binding since
it follows the SoC design. Yet I doubt if this routing logic will
never break.

Any suggestion, Rob?

Patch

diff --git a/Documentation/devicetree/bindings/sound/fsl,audmix.txt b/Documentation/devicetree/bindings/sound/fsl,audmix.txt
new file mode 100644
index 0000000..840b7e0
--- /dev/null
+++ b/Documentation/devicetree/bindings/sound/fsl,audmix.txt
@@ -0,0 +1,50 @@ 
+NXP Audio Mixer (AUDMIX).
+
+The Audio Mixer is a on-chip functional module that allows mixing of two
+audio streams into a single audio stream. Audio Mixer has two input serial
+audio interfaces. These are driven by two Synchronous Audio interface
+modules (SAI). Each input serial interface carries 8 audio channels in its
+frame in TDM manner. Mixer mixes audio samples of corresponding channels
+from two interfaces into a single sample. Before mixing, audio samples of
+two inputs can be attenuated based on configuration. The output of the
+Audio Mixer is also a serial audio interface. Like input interfaces it has
+the same TDM frame format. This output is used to drive the serial DAC TDM
+interface of audio codec and also sent to the external pins along with the
+receive path of normal audio SAI module for readback by the CPU.
+
+The output of Audio Mixer can be selected from any of the three streams
+ - serial audio input 1
+ - serial audio input 2
+ - mixed audio
+
+Mixing operation is independent of audio sample rate but the two audio
+input streams must have same audio sample rate with same number of channels
+in TDM frame to be eligible for mixing.
+
+Device driver required properties:
+=================================
+  - compatible		: Compatible list, contains "fsl,imx8qm-audmix"
+
+  - reg			: Offset and length of the register set for the device.
+
+  - clocks		: Must contain an entry for each entry in clock-names.
+
+  - clock-names		: Must include the "ipg" for register access.
+
+  - power-domains	: Must contain the phandle to AUDMIX power domain node
+
+  - dais		: Must contain a list of phandles to AUDMIX connected
+			  DAIs. The current implementation requires two phandles
+			  to SAI interfaces to be provided, the first SAI in the
+			  list being used to route the AUDMIX output.
+
+Device driver configuration example:
+======================================
+  audmix: audmix@59840000 {
+    compatible = "fsl,imx8qm-audmix";
+    reg = <0x0 0x59840000 0x0 0x10000>;
+    clocks = <&clk IMX8QXP_AUD_AUDMIX_IPG>;
+    clock-names = "ipg";
+    power-domains = <&pd_audmix>;
+    dais = <&sai4>, <&sai5>;
+  };