linux-kernel - [PATCH v3 1/2] ASoC: dt-bindings: sound-card-common: List DAPM endpoints ignoring system suspend

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Date:   Wed, 11 Oct 2023 19:47:58 +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 v3 1/2] ASoC: dt-bindings: sound-card-common: 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. For example 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. LPA requires some audio paths still enabled when
Cortex-A enters into suspend.

Signed-off-by: Chancel Liu <chancel.liu@....com>
---
 .../bindings/sound/sound-card-common.yaml          | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/Documentation/devicetree/bindings/sound/sound-card-common.yaml b/Documentation/devicetree/bindings/sound/sound-card-common.yaml
index 3a941177f684..f43147c78651 100644
--- a/Documentation/devicetree/bindings/sound/sound-card-common.yaml
+++ b/Documentation/devicetree/bindings/sound/sound-card-common.yaml
@@ -17,6 +17,20 @@ properties:
       pair of strings, the first being the connection's sink, the second
       being the connection's source.
 
+  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. For example 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. LPA requires some audio paths
+      still enabled when Cortex-A enters into suspend.
+
   model:
     $ref: /schemas/types.yaml#/definitions/string
     description: User specified audio sound card name
-- 
2.25.1