linux-kernel - [PATCH AUTOSEL 4.19 05/12] ARM: dts: rockchip: disable arm_global

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Date:   Mon, 28 Nov 2022 12:42:28 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Johan Jonker <jbx6244@...il.com>, Heiko Stuebner <heiko@...ech.de>,
        Sasha Levin <sashal@...nel.org>, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, devicetree@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 05/12] ARM: dts: rockchip: disable arm_global_timer on rk3066 and rk3188

From: Johan Jonker <jbx6244@...il.com>

[ Upstream commit da74858a475782a3f16470907814c8cc5950ad68 ]

The clock source and the sched_clock provided by the arm_global_timer
on Rockchip rk3066a/rk3188 are quite unstable because their rates
depend on the CPU frequency.

Recent changes to the arm_global_timer driver makes it impossible to use.

On the other side, the arm_global_timer has a higher rating than the
ROCKCHIP_TIMER, it will be selected by default by the time framework
while we want to use the stable Rockchip clock source.

Keep the arm_global_timer disabled in order to have the
DW_APB_TIMER (rk3066a) or ROCKCHIP_TIMER (rk3188) selected by default.

Signed-off-by: Johan Jonker <jbx6244@...il.com>
Link: https://lore.kernel.org/r/f275ca8d-fd0a-26e5-b978-b7f3df815e0a@gmail.com
Signed-off-by: Heiko Stuebner <heiko@...ech.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/arm/boot/dts/rk3188.dtsi | 1 -
 arch/arm/boot/dts/rk3xxx.dtsi | 7 +++++++
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm/boot/dts/rk3188.dtsi b/arch/arm/boot/dts/rk3188.dtsi
index 3b7cae6f4127..24efc9b31d89 100644
--- a/arch/arm/boot/dts/rk3188.dtsi
+++ b/arch/arm/boot/dts/rk3188.dtsi
@@ -509,7 +509,6 @@ &emac {
 
 &global_timer {
 	interrupts = <GIC_PPI 11 (GIC_CPU_MASK_SIMPLE(4) | IRQ_TYPE_EDGE_RISING)>;
-	status = "disabled";
 };
 
 &local_timer {
diff --git a/arch/arm/boot/dts/rk3xxx.dtsi b/arch/arm/boot/dts/rk3xxx.dtsi
index 86a0d98d28ff..1b6429843bd4 100644
--- a/arch/arm/boot/dts/rk3xxx.dtsi
+++ b/arch/arm/boot/dts/rk3xxx.dtsi
@@ -108,6 +108,13 @@ global_timer: global-timer@...3c200 {
 		reg = <0x1013c200 0x20>;
 		interrupts = <GIC_PPI 11 (GIC_CPU_MASK_SIMPLE(2) | IRQ_TYPE_EDGE_RISING)>;
 		clocks = <&cru CORE_PERI>;
+		status = "disabled";
+		/* The clock source and the sched_clock provided by the arm_global_timer
+		 * on Rockchip rk3066a/rk3188 are quite unstable because their rates
+		 * depend on the CPU frequency.
+		 * Keep the arm_global_timer disabled in order to have the
+		 * DW_APB_TIMER (rk3066a) or ROCKCHIP_TIMER (rk3188) selected by default.
+		 */
 	};
 
 	local_timer: local-timer@...3c600 {
-- 
2.35.1