* [PATCH] arm64: tegra: Disable secondary CPUs on Tegra194
@ 2019-11-08 15:37 Thierry Reding
2019-11-08 16:04 ` Mark Rutland
0 siblings, 1 reply; 2+ messages in thread
From: Thierry Reding @ 2019-11-08 15:37 UTC (permalink / raw)
To: Thierry Reding; +Cc: Jon Hunter, linux-tegra, devicetree
From: Thierry Reding <treding@nvidia.com>
According to ePAPR, CPUs that are quiescent should have the "status"
property of the corresponding device tree node set to "disabled". Since
all but the boot CPU are in a quiescent state on boot, mark all
secondary CPUs as "disabled".
Note that this does not have an impact on SMP. Linux will still be able
to boot these secondary CPUs like before.
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
arch/arm64/boot/dts/nvidia/tegra194.dtsi | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/arch/arm64/boot/dts/nvidia/tegra194.dtsi b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
index 59485976db64..ea165b2998f9 100644
--- a/arch/arm64/boot/dts/nvidia/tegra194.dtsi
+++ b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
@@ -1661,6 +1661,7 @@
compatible = "nvidia,tegra194-carmel";
device_type = "cpu";
reg = <0x001>;
+ status = "disabled";
enable-method = "psci";
i-cache-size = <131072>;
i-cache-line-size = <64>;
@@ -1675,6 +1676,7 @@
compatible = "nvidia,tegra194-carmel";
device_type = "cpu";
reg = <0x100>;
+ status = "disabled";
enable-method = "psci";
i-cache-size = <131072>;
i-cache-line-size = <64>;
@@ -1689,6 +1691,7 @@
compatible = "nvidia,tegra194-carmel";
device_type = "cpu";
reg = <0x101>;
+ status = "disabled";
enable-method = "psci";
i-cache-size = <131072>;
i-cache-line-size = <64>;
@@ -1703,6 +1706,7 @@
compatible = "nvidia,tegra194-carmel";
device_type = "cpu";
reg = <0x200>;
+ status = "disabled";
enable-method = "psci";
i-cache-size = <131072>;
i-cache-line-size = <64>;
@@ -1717,6 +1721,7 @@
compatible = "nvidia,tegra194-carmel";
device_type = "cpu";
reg = <0x201>;
+ status = "disabled";
enable-method = "psci";
i-cache-size = <131072>;
i-cache-line-size = <64>;
@@ -1731,6 +1736,7 @@
compatible = "nvidia,tegra194-carmel";
device_type = "cpu";
reg = <0x300>;
+ status = "disabled";
enable-method = "psci";
i-cache-size = <131072>;
i-cache-line-size = <64>;
@@ -1745,6 +1751,7 @@
compatible = "nvidia,tegra194-carmel";
device_type = "cpu";
reg = <0x301>;
+ status = "disabled";
enable-method = "psci";
i-cache-size = <131072>;
i-cache-line-size = <64>;
--
2.23.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH] arm64: tegra: Disable secondary CPUs on Tegra194
2019-11-08 15:37 [PATCH] arm64: tegra: Disable secondary CPUs on Tegra194 Thierry Reding
@ 2019-11-08 16:04 ` Mark Rutland
0 siblings, 0 replies; 2+ messages in thread
From: Mark Rutland @ 2019-11-08 16:04 UTC (permalink / raw)
To: Thierry Reding; +Cc: Jon Hunter, linux-tegra, devicetree
On Fri, Nov 08, 2019 at 04:37:19PM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding@nvidia.com>
>
> According to ePAPR, CPUs that are quiescent should have the "status"
> property of the corresponding device tree node set to "disabled". Since
> all but the boot CPU are in a quiescent state on boot, mark all
> secondary CPUs as "disabled".
I think it might be best to leave this as-is, as we haven't done this
for other dts, and the OS doesn't actually require or consume this
regardless.
Adding this to all the Dts seems like unnecessary churn, and we can fix
the DT spec instead.
Thanks,
Mark.
>
> Note that this does not have an impact on SMP. Linux will still be able
> to boot these secondary CPUs like before.
>
> Signed-off-by: Thierry Reding <treding@nvidia.com>
> ---
> arch/arm64/boot/dts/nvidia/tegra194.dtsi | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/arch/arm64/boot/dts/nvidia/tegra194.dtsi b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
> index 59485976db64..ea165b2998f9 100644
> --- a/arch/arm64/boot/dts/nvidia/tegra194.dtsi
> +++ b/arch/arm64/boot/dts/nvidia/tegra194.dtsi
> @@ -1661,6 +1661,7 @@
> compatible = "nvidia,tegra194-carmel";
> device_type = "cpu";
> reg = <0x001>;
> + status = "disabled";
> enable-method = "psci";
> i-cache-size = <131072>;
> i-cache-line-size = <64>;
> @@ -1675,6 +1676,7 @@
> compatible = "nvidia,tegra194-carmel";
> device_type = "cpu";
> reg = <0x100>;
> + status = "disabled";
> enable-method = "psci";
> i-cache-size = <131072>;
> i-cache-line-size = <64>;
> @@ -1689,6 +1691,7 @@
> compatible = "nvidia,tegra194-carmel";
> device_type = "cpu";
> reg = <0x101>;
> + status = "disabled";
> enable-method = "psci";
> i-cache-size = <131072>;
> i-cache-line-size = <64>;
> @@ -1703,6 +1706,7 @@
> compatible = "nvidia,tegra194-carmel";
> device_type = "cpu";
> reg = <0x200>;
> + status = "disabled";
> enable-method = "psci";
> i-cache-size = <131072>;
> i-cache-line-size = <64>;
> @@ -1717,6 +1721,7 @@
> compatible = "nvidia,tegra194-carmel";
> device_type = "cpu";
> reg = <0x201>;
> + status = "disabled";
> enable-method = "psci";
> i-cache-size = <131072>;
> i-cache-line-size = <64>;
> @@ -1731,6 +1736,7 @@
> compatible = "nvidia,tegra194-carmel";
> device_type = "cpu";
> reg = <0x300>;
> + status = "disabled";
> enable-method = "psci";
> i-cache-size = <131072>;
> i-cache-line-size = <64>;
> @@ -1745,6 +1751,7 @@
> compatible = "nvidia,tegra194-carmel";
> device_type = "cpu";
> reg = <0x301>;
> + status = "disabled";
> enable-method = "psci";
> i-cache-size = <131072>;
> i-cache-line-size = <64>;
> --
> 2.23.0
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2019-11-08 15:37 [PATCH] arm64: tegra: Disable secondary CPUs on Tegra194 Thierry Reding
2019-11-08 16:04 ` Mark Rutland
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