linux-kernel - [PATCH] arm64: dts: allwinner: Mark timer as stopped in suspend

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Date:   Sat,  8 Aug 2020 21:18:22 -0500
From:   Samuel Holland <samuel@...lland.org>
To:     Maxime Ripard <mripard@...nel.org>, Chen-Yu Tsai <wens@...e.org>
Cc:     devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, Samuel Holland <samuel@...lland.org>
Subject: [PATCH] arm64: dts: allwinner: Mark timer as stopped in suspend

When possible, system firmware on 64-bit Allwinner platforms disables
OSC24M during system suspend. Since this oscillator is the clock source
for the ARM architectural timer, this causes the timer to stop counting.
Therefore, the ARM architectural timer must not be marked as NONSTOP on
these platforms, or the time will be wrong after system resume.

Adding the arm,no-tick-in-suspend property forces the kernel to ignore
the ARM architectural timer when calculating sleeptime; it falls back to
reading the RTC. Note that this only affects deep suspend, not s2idle.

Signed-off-by: Samuel Holland <samuel@...lland.org>
---
 arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi | 1 +
 arch/arm64/boot/dts/allwinner/sun50i-h5.dtsi  | 1 +
 arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi  | 1 +
 3 files changed, 3 insertions(+)

diff --git a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
index 8dfbcd144072..5d19cf6f6d4f 100644
--- a/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
+++ b/arch/arm64/boot/dts/allwinner/sun50i-a64.dtsi
@@ -157,6 +157,7 @@ link_codec: simple-audio-card,codec {
 	timer {
 		compatible = "arm,armv8-timer";
 		allwinner,erratum-unknown1;
+		arm,no-tick-in-suspend;
 		interrupts = <GIC_PPI 13
 			(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_HIGH)>,
 			     <GIC_PPI 14
diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h5.dtsi b/arch/arm64/boot/dts/allwinner/sun50i-h5.dtsi
index 4462a68c0681..a6c8b43b99a3 100644
--- a/arch/arm64/boot/dts/allwinner/sun50i-h5.dtsi
+++ b/arch/arm64/boot/dts/allwinner/sun50i-h5.dtsi
@@ -53,6 +53,7 @@ psci {
 
 	timer {
 		compatible = "arm,armv8-timer";
+		arm,no-tick-in-suspend;
 		interrupts = <GIC_PPI 13
 				(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_LOW)>,
 			     <GIC_PPI 14
diff --git a/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi b/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi
index 9ce78a7b117d..28c77d6872f6 100644
--- a/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi
+++ b/arch/arm64/boot/dts/allwinner/sun50i-h6.dtsi
@@ -90,6 +90,7 @@ psci {
 
 	timer {
 		compatible = "arm,armv8-timer";
+		arm,no-tick-in-suspend;
 		interrupts = <GIC_PPI 13
 			(GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_LEVEL_HIGH)>,
 			     <GIC_PPI 14
-- 
2.26.2