linux-kernel - [PATCH 4/4] arm64: dts: imx8mq-librem5-r3: workaround i2c1 issue with 1GHz cpu voltage

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Date:   Fri, 18 Dec 2020 11:31:31 +0100
From:   Martin Kepplinger <martin.kepplinger@...i.sm>
To:     robh@...nel.org, shawnguo@...nel.org, festevam@...il.com
Cc:     kernel@...gutronix.de, linux-imx@....com, krzk@...nel.org,
        kernel@...i.sm, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Martin Kepplinger <martin.kepplinger@...i.sm>
Subject: [PATCH 4/4] arm64: dts: imx8mq-librem5-r3: workaround i2c1 issue with 1GHz cpu voltage

This is a workaround for a hardware bug in the r3 revision that basically would
stop the system due to traffic on the i2c1 bus. A cpu voltage change would
trigger such traffic and that's what is avoided in order to work around it.

Signed-off-by: Martin Kepplinger <martin.kepplinger@...i.sm>
---
 arch/arm64/boot/dts/freescale/imx8mq-librem5-r3.dts | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm64/boot/dts/freescale/imx8mq-librem5-r3.dts b/arch/arm64/boot/dts/freescale/imx8mq-librem5-r3.dts
index 6704ea2c72a3..0d38327043f8 100644
--- a/arch/arm64/boot/dts/freescale/imx8mq-librem5-r3.dts
+++ b/arch/arm64/boot/dts/freescale/imx8mq-librem5-r3.dts
@@ -10,6 +10,12 @@
 	compatible = "purism,librem5r3", "purism,librem5", "fsl,imx8mq";
 };
 
+&a53_opp_table {
+	opp-1000000000 {
+		opp-microvolt = <1000000>;
+	};
+};
+
 &accel_gyro {
 	mount-matrix =  "1",  "0",  "0",
 			"0",  "1",  "0",
-- 
2.20.1