linux-kernel - [PATCH v1 1/4] arm64: dts: imx8mq-librem5: set audio-1v8 always-on

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Date:   Mon, 17 Jul 2023 10:00:53 +0000
From:   Martin Kepplinger <martink@...teo.de>
To:     robh+dt@...nel.org, krzysztof.kozlowski+dt@...aro.org,
        conor+dt@...nel.org, shawnguo@...nel.org, festevam@...il.com
Cc:     kernel@...gutronix.de, linux-imx@....com, kernel@...i.sm,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, phone-devel@...r.kernel.org,
        Martin Kepplinger <martin.kepplinger@...i.sm>
Subject: [PATCH v1 1/4] arm64: dts: imx8mq-librem5: set audio-1v8 always-on

From: Martin Kepplinger <martin.kepplinger@...i.sm>

Unfortunately the codec can't be switched off on it's own. It would ground
the whole bus it's connected to (because of it's built-in diodes to VDD on
i2c pins), making all the other devices on the same bus inaccessible:

[    0.237154] lm3692x 2-0036: Cannot read/clear faults: -11
[    0.242628] lm3692x 2-0036: Fail writing initialization values
[    0.286462] [drm:drm_bridge_attach] *ERROR* failed to attach bridge /soc@...us@...00000/mipi-dsi@...00000 to encoder None-34: -517

Work around this hardware limitation by keeping audio-1v8 enabled.

Signed-off-by: Martin Kepplinger <martin.kepplinger@...i.sm>
---
 arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi b/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
index 38732579d13e9..ab47bdc35cebd 100644
--- a/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
+++ b/arch/arm64/boot/dts/freescale/imx8mq-librem5.dtsi
@@ -91,6 +91,7 @@ reg_aud_1v8: regulator-audio-1v8 {
 		regulator-max-microvolt = <1800000>;
 		gpio = <&gpio1 4 GPIO_ACTIVE_HIGH>;
 		enable-active-high;
+		regulator-always-on;
 	};
 
 	reg_mic_2v4: regulator-mic-2v4 {
-- 
2.30.2