2022-10-30 21:31:25

by Johan Jonker

Subject: [PATCH v2] ARM: dts: rockchip: rk3xx: disable arm_global_timer

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 <[email protected]>
---

ARM: dts: rockchip: disable arm-global-timer for rk3188
https://lore.kernel.org/linux-rockchip/[email protected]/

clocksource: arm_global_timer: implement rate compensation whenever source clock changes
https://lore.kernel.org/all/[email protected]/
---
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 cdd4a0bd5..486a96ce2 100644
--- a/arch/arm/boot/dts/rk3188.dtsi
+++ b/arch/arm/boot/dts/rk3188.dtsi
@@ -607,7 +607,6 @@

&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 bf285091a..b0ec459ff 100644
--- a/arch/arm/boot/dts/rk3xxx.dtsi
+++ b/arch/arm/boot/dts/rk3xxx.dtsi
@@ -76,6 +76,13 @@
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@1013c600 {
--
2.20.1

2022-11-15 11:50:11

by Heiko Stuebner

Subject: Re: [PATCH v2] ARM: dts: rockchip: rk3xx: disable arm_global_timer

On Sun, 30 Oct 2022 21:56:29 +0100, Johan Jonker wrote:
> 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.
>
> [...]

Applied, thanks!

[1/1] ARM: dts: rockchip: rk3xx: disable arm_global_timer
commit: da74858a475782a3f16470907814c8cc5950ad68

Best regards,
--
Heiko Stuebner <[email protected]>