[PATCH 1/2] dt-bindings: cpufreq: Add big CPU supply

[PATCH 1/2] dt-bindings: cpufreq: Add big CPU supply

[Nícolas F. R. A. Prado]

The performance-controller hardware block on MediaTek SoCs is
responsible for controlling the frequency of the CPUs. As such, it needs
any CPU regulator to have been configured prior to initializing. Add a
phandle in the binding so this dependency can be described.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
---

 .../devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml        | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
index d0aecde2b89b..d75b01d04998 100644
--- a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
+++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
@@ -33,6 +33,8 @@ properties:
       performance domains.
     const: 1
 
+  big-cpus-supply: true
+
 required:
   - compatible
   - reg
-- 
2.43.0

[PATCH 2/2] arm64: dts: mediatek: cherry: Add CPU supply dependency to cpufreq-hw

[Nícolas F. R. A. Prado]

When the mediatek-cpufreq-hw driver enables the hardware (by
writing to REG_FREQ_ENABLE), if the regulator supplying the voltage to
the big CPUs hasn't probed yet, the platform hangs shortly after and
"rcu: INFO: rcu_preempt detected stalls on CPUs/tasks" are printed in
the log.

To prevent this from happening, describe the big CPUs regulator in the
performance-controller DT node, so that devlink ensures the regulator
has been probed and configured before the frequency scaling hardware is
probed and enabled.

Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>

---

 arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
index dd5b89b73190..505da60eee90 100644
--- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
+++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
@@ -502,6 +502,10 @@ &pcie1 {
 	pinctrl-0 = <&pcie1_pins_default>;
 };
 
+&performance {
+	big-cpus-supply = <&mt6315_6_vbuck1>;
+};
+
 &pio {
 	mediatek,rsel-resistance-in-si-unit;
 	pinctrl-names = "default";
-- 
2.43.0

Re: [PATCH 2/2] arm64: dts: mediatek: cherry: Add CPU supply dependency to cpufreq-hw

[Viresh Kumar]

On 29-12-23, 18:28, Nícolas F. R. A. Prado wrote:
> When the mediatek-cpufreq-hw driver enables the hardware (by
> writing to REG_FREQ_ENABLE), if the regulator supplying the voltage to
> the big CPUs hasn't probed yet, the platform hangs shortly after and
> "rcu: INFO: rcu_preempt detected stalls on CPUs/tasks" are printed in
> the log.
> 
> To prevent this from happening, describe the big CPUs regulator in the
> performance-controller DT node, so that devlink ensures the regulator
> has been probed and configured before the frequency scaling hardware is
> probed and enabled.
> 
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
> 
> ---
> 
>  arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
> index dd5b89b73190..505da60eee90 100644
> --- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
> +++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
> @@ -502,6 +502,10 @@ &pcie1 {
>  	pinctrl-0 = <&pcie1_pins_default>;
>  };
>  
> +&performance {
> +	big-cpus-supply = <&mt6315_6_vbuck1>;
> +};
> +
>  &pio {
>  	mediatek,rsel-resistance-in-si-unit;
>  	pinctrl-names = "default";

I think the regulator needs to be mentioned in the CPU's node and not
here ?

-- 
viresh

Re: [PATCH 2/2] arm64: dts: mediatek: cherry: Add CPU supply dependency to cpufreq-hw

[AngeloGioacchino Del Regno]

Il 02/01/24 07:11, Viresh Kumar ha scritto:
> On 29-12-23, 18:28, Nícolas F. R. A. Prado wrote:
>> When the mediatek-cpufreq-hw driver enables the hardware (by
>> writing to REG_FREQ_ENABLE), if the regulator supplying the voltage to
>> the big CPUs hasn't probed yet, the platform hangs shortly after and
>> "rcu: INFO: rcu_preempt detected stalls on CPUs/tasks" are printed in
>> the log.
>>
>> To prevent this from happening, describe the big CPUs regulator in the
>> performance-controller DT node, so that devlink ensures the regulator
>> has been probed and configured before the frequency scaling hardware is
>> probed and enabled.
>>
>> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
>>
>> ---
>>
>>   arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi | 4 ++++
>>   1 file changed, 4 insertions(+)
>>
>> diff --git a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>> index dd5b89b73190..505da60eee90 100644
>> --- a/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>> +++ b/arch/arm64/boot/dts/mediatek/mt8195-cherry.dtsi
>> @@ -502,6 +502,10 @@ &pcie1 {
>>   	pinctrl-0 = <&pcie1_pins_default>;
>>   };
>>   
>> +&performance {
>> +	big-cpus-supply = <&mt6315_6_vbuck1>;
>> +};
>> +
>>   &pio {
>>   	mediatek,rsel-resistance-in-si-unit;
>>   	pinctrl-names = "default";
> 
> I think the regulator needs to be mentioned in the CPU's node and not
> here ?
> 

Even if the regulator voltage is being changed by firmware with cpufreq-hw, the
actual regulators should go to each CPU node and not in the cpufreq driver node,
I agree with Viresh.

Besides, that's the same thing that we're doing with mediatek-cpufreq as well...
and since we're talking about that, we should also do something about this such
that we stop declaring `regulator-always-on` for CPU cores in devicetree, but
this is probably slightly out of context for what you're trying to do here, so,
read that as an "extra consideration" :-)

Cheers,
Angelo

Re: [PATCH 1/2] dt-bindings: cpufreq: Add big CPU supply

[Krzysztof Kozlowski]

On 29/12/2023 22:28, Nícolas F. R. A. Prado wrote:
> The performance-controller hardware block on MediaTek SoCs is
> responsible for controlling the frequency of the CPUs. As such, it needs
> any CPU regulator to have been configured prior to initializing. Add a
> phandle in the binding so this dependency can be described.
> 
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
> ---
> 
>  .../devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml        | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
> index d0aecde2b89b..d75b01d04998 100644
> --- a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
> +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
> @@ -33,6 +33,8 @@ properties:
>        performance domains.
>      const: 1
>  
> +  big-cpus-supply: true

Why big? Neither little nor medium need power? Why you do not need to
provide all supplies?

About the naming, use something matching the devices, e.g. from their
datasheet/manual.

Best regards,
Krzysztof

Re: [PATCH 1/2] dt-bindings: cpufreq: Add big CPU supply

[Rob Herring]

On Fri, Dec 29, 2023 at 06:28:39PM -0300, Nícolas F. R. A. Prado wrote:
> The performance-controller hardware block on MediaTek SoCs is
> responsible for controlling the frequency of the CPUs. As such, it needs
> any CPU regulator to have been configured prior to initializing. Add a
> phandle in the binding so this dependency can be described.
> 
> Signed-off-by: Nícolas F. R. A. Prado <nfraprado@collabora.com>
> ---
> 
>  .../devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml        | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
> index d0aecde2b89b..d75b01d04998 100644
> --- a/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
> +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-mediatek-hw.yaml
> @@ -33,6 +33,8 @@ properties:
>        performance domains.
>      const: 1
>  
> +  big-cpus-supply: true
> +

A CPU's supply belongs in the respective CPU nodes.

Rob