linux-kernel - [PATCH v2 1/2] ASoC: dt-bindings: fsl_rpmsg: List DAPM endpoints ignoring system suspend

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Date:   Mon, 25 Sep 2023 19:09:45 +0800
From:   Chancel Liu <chancel.liu@....com>
To:     lgirdwood@...il.com, broonie@...nel.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        shengjiu.wang@...il.com, Xiubo.Lee@...il.com, festevam@...il.com,
        nicoleotsuka@...il.com, perex@...ex.cz, tiwai@...e.com,
        shawnguo@...nel.org, s.hauer@...gutronix.de, kernel@...gutronix.de,
        alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     Chancel Liu <chancel.liu@....com>
Subject: [PATCH v2 1/2] ASoC: dt-bindings: fsl_rpmsg: List DAPM endpoints ignoring system suspend

Add a property to list DAPM endpoints which mark paths between these
endpoints should not be disabled when system enters in suspend state.

LPA means low power audio case. 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 can be explained as a
mechanism 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. LPA requires some audio paths still enabled
when Cortex-A enters into suspend.

Signed-off-by: Chancel Liu <chancel.liu@....com>
---
 .../devicetree/bindings/sound/fsl,rpmsg.yaml      | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml b/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
index 188f38baddec..d8fd17615bf2 100644
--- a/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
+++ b/Documentation/devicetree/bindings/sound/fsl,rpmsg.yaml
@@ -91,6 +91,21 @@ properties:
       - rpmsg-audio-channel
       - rpmsg-micfil-channel
 
+  fsl,lpa-widgets:
+    $ref: /schemas/types.yaml#/definitions/non-unique-string-array
+    description: |
+      A list of DAPM endpoints which mark paths between these endpoints should
+      not be disabled when system enters in suspend state. LPA means low power
+      audio case. 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 can be explained as a mechanism 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. LPA requires
+      some audio paths still enabled when Cortex-A enters into suspend.
+
 required:
   - compatible
 
-- 
2.25.1