> > Add a property to list DAPM endpoints which mark paths between these > > endpoints ignoring suspend. These DAPM paths can still be power on > > when system enters into suspend. > > > > Signed-off-by: Chancel Liu <chancel.liu@xxxxxxx> > > --- > > Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml | 6 ++++++ > > 1 file changed, 6 insertions(+) > > > > diff --git a/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml > > b/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml > > index 188f38baddec..ec6e09eab427 100644 > > --- a/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml > > +++ b/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml > > @@ -91,6 +91,12 @@ properties: > > - rpmsg-audio-channel > > - rpmsg-micfil-channel > > > > + fsl,lpa-widgets: > > What is LPA? It's not explained in property description. > On asymmetric multiprocessor, there are Cortex-A core and Cortex-M core, Linux is running on Cortex-A core, RTOS or other OS is running on Cortex-M core. The audio hardware devices can be controlled by Cortex-M. LPA means low power audio case. The mechanism can be explained that Cortex-A allocates a large buffer and fill audio data, then Cortex-A can enter into suspend for the purpose of power saving. Cortex-M continues to play the sound during suspend phase of Cortex-A. When the data in buffer is consumed, Cortex-M will trigger the Cortex-A to wakeup to fill data. I can add above explanation to LPA in patch v2. > > + $ref: /schemas/types.yaml#/definitions/non-unique-string-array > > + description: | > > + A list of DAPM endpoints which mark paths between these endpoints > > + ignoring suspend. > > And how does it differ from audio-routing? Also, you need to explain what is > "suspend" in this context. Bindings are independent of Linux. > Normally audio paths will be disabled by ASoC dynamic audio power management if Linux enters into suspend. LPA requires some audio paths enabled when Cortex-A enters into suspend. We can read DAPM endpoints from the "fsl,lpa-widgets" property and keep the paths between these endpoints enabled during suspend phase of Cortex-A. Property "audio-routing" just declares the connection between widgets and doesn't have such feature. I will modify the description as following: "A list of DAPM endpoints which mark paths between these endpoints still enabled when system enters into suspend." > Best regards, > Krzysztof Regards, Chancel Liu
