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[PATCH v14 7/7] riscv: dts: thead: Add PWM fan and thermal control

Michal Wilczynski posted 7 patches 1 month, 2 weeks ago
There is a newer version of this series
[PATCH v14 7/7] riscv: dts: thead: Add PWM fan and thermal control
Posted by Michal Wilczynski 1 month, 2 weeks ago 
Add Device Tree nodes to enable a PWM controlled fan and it's associated
thermal management for the Lichee Pi 4A board.

This enables temperature-controlled active cooling for the Lichee Pi 4A
board based on SoC temperature.

Reviewed-by: Drew Fustini <fustini@kernel.org>
Tested-by: Drew Fustini <fustini@kernel.org>
Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
---
 arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts | 67 +++++++++++++++++++++++
 1 file changed, 67 insertions(+)

diff --git a/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts b/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts
index 4020c727f09e8e2286fdc7fecd79dbd8eba69556..c58c2085ca92a3234f1350500cedae4157f0c35f 100644
--- a/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts
+++ b/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts
@@ -28,9 +28,76 @@ aliases {
 	chosen {
 		stdout-path = "serial0:115200n8";
 	};
+
+	thermal-zones {
+		cpu-thermal {
+			polling-delay = <1000>;
+			polling-delay-passive = <1000>;
+			thermal-sensors = <&pvt 0>;
+
+			trips {
+				fan_config0: fan-trip0 {
+					temperature = <39000>;
+					hysteresis = <5000>;
+					type = "active";
+				};
+
+				fan_config1: fan-trip1 {
+					temperature = <50000>;
+					hysteresis = <5000>;
+					type = "active";
+				};
+
+				fan_config2: fan-trip2 {
+					temperature = <60000>;
+					hysteresis = <5000>;
+					type = "active";
+				};
+			};
+
+			cooling-maps {
+				map-active-0 {
+					cooling-device = <&fan 1 1>;
+					trip = <&fan_config0>;
+				};
+
+				map-active-1 {
+					cooling-device = <&fan 2 2>;
+					trip = <&fan_config1>;
+				};
+
+				map-active-2 {
+					cooling-device = <&fan 3 3>;
+					trip = <&fan_config2>;
+				};
+			};
+		};
+	};
+
+	fan: pwm-fan {
+		pinctrl-names = "default";
+		pinctrl-0 = <&fan_pins>;
+		compatible = "pwm-fan";
+		#cooling-cells = <2>;
+		pwms = <&pwm 1 10000000 0>;
+		cooling-levels = <0 66 196 255>;
+	};
+
 };
 
 &padctrl0_apsys {
+	fan_pins: fan-0 {
+		pwm1-pins {
+			pins = "GPIO3_3"; /* PWM1 */
+			function = "pwm";
+			bias-disable;
+			drive-strength = <25>;
+			input-disable;
+			input-schmitt-disable;
+			slew-rate = <0>;
+		};
+	};
+
 	uart0_pins: uart0-0 {
 		tx-pins {
 			pins = "UART0_TXD";

-- 
2.34.1
Re: [PATCH v14 7/7] riscv: dts: thead: Add PWM fan and thermal control
Posted by Drew Fustini 1 month, 1 week ago 
On Wed, Aug 20, 2025 at 10:35:42AM +0200, Michal Wilczynski wrote:
> Add Device Tree nodes to enable a PWM controlled fan and it's associated
> thermal management for the Lichee Pi 4A board.
> 
> This enables temperature-controlled active cooling for the Lichee Pi 4A
> board based on SoC temperature.
> 
> Reviewed-by: Drew Fustini <fustini@kernel.org>
> Tested-by: Drew Fustini <fustini@kernel.org>
> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
> ---
>  arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts | 67 +++++++++++++++++++++++
>  1 file changed, 67 insertions(+)

Do you think it makes sense to coordinate this with the "Initial thermal
management for Lichee Pi 4A board" series [1] from Icenowy?

Thanks,
Drew

[1] https://lore.kernel.org/linux-riscv/20250816093209.2600355-1-uwu@icenowy.me/
Re: [PATCH v14 7/7] riscv: dts: thead: Add PWM fan and thermal control
Posted by Michal Wilczynski 1 month, 1 week ago 

On 8/22/25 22:49, Drew Fustini wrote:
> On Wed, Aug 20, 2025 at 10:35:42AM +0200, Michal Wilczynski wrote:
>> Add Device Tree nodes to enable a PWM controlled fan and it's associated
>> thermal management for the Lichee Pi 4A board.
>>
>> This enables temperature-controlled active cooling for the Lichee Pi 4A
>> board based on SoC temperature.
>>
>> Reviewed-by: Drew Fustini <fustini@kernel.org>
>> Tested-by: Drew Fustini <fustini@kernel.org>
>> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
>> ---
>>  arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts | 67 +++++++++++++++++++++++
>>  1 file changed, 67 insertions(+)
> 
> Do you think it makes sense to coordinate this with the "Initial thermal
> management for Lichee Pi 4A board" series [1] from Icenowy?

Hi,
It seems to me like using the HW PWM is just a better solution for
driving the fans. However as pointed in the discussion currently Rust
requires LLVM, so people compiling with gcc will not be able to compile
the driver for some time until the gcc support becomes better.

I think there is a way to express in Device Tree the fallback logic -
if Rust not available then use SW PWM. So I guess the pragmatic way to
go is to merge SW PWM temporary fix first, and later when gcc becomes
better at compiling Rust patch it up to use HW PWM instead.

> 
> Thanks,
> Drew
> 
> [1] https://lore.kernel.org/linux-riscv/20250816093209.2600355-1-uwu@icenowy.me/
> 

Best regards,
-- 
Michal Wilczynski <m.wilczynski@samsung.com>
Re: [PATCH v14 7/7] riscv: dts: thead: Add PWM fan and thermal control
Posted by Miguel Ojeda 1 month, 1 week ago 
On Sat, Aug 23, 2025 at 12:14 PM Michal Wilczynski
<m.wilczynski@samsung.com> wrote:
>
> However as pointed in the discussion currently Rust
> requires LLVM, so people compiling with gcc will not be able to compile
> the driver for some time until the gcc support becomes better.

In case it helps/clarifies: the C side can be built with GCC (i.e.
building without `LLVM=1`, with Rust using its LLVM backend), but it
is a best-effort hack and the goal is to eventually use
`rustc_codegen_gcc` and/or GCC Rust. Some users/distributions use it
nevertheless.

Cheers,
Miguel
Re: [PATCH v14 7/7] riscv: dts: thead: Add PWM fan and thermal control
Posted by Michal Wilczynski 1 month, 1 week ago 

On 8/23/25 12:13, Michal Wilczynski wrote:
> 
> 
> On 8/22/25 22:49, Drew Fustini wrote:
>> On Wed, Aug 20, 2025 at 10:35:42AM +0200, Michal Wilczynski wrote:
>>> Add Device Tree nodes to enable a PWM controlled fan and it's associated
>>> thermal management for the Lichee Pi 4A board.
>>>
>>> This enables temperature-controlled active cooling for the Lichee Pi 4A
>>> board based on SoC temperature.
>>>
>>> Reviewed-by: Drew Fustini <fustini@kernel.org>
>>> Tested-by: Drew Fustini <fustini@kernel.org>
>>> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
>>> ---
>>>  arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts | 67 +++++++++++++++++++++++
>>>  1 file changed, 67 insertions(+)
>>
>> Do you think it makes sense to coordinate this with the "Initial thermal
>> management for Lichee Pi 4A board" series [1] from Icenowy?
> 
> Hi,
> It seems to me like using the HW PWM is just a better solution for
> driving the fans. However as pointed in the discussion currently Rust
> requires LLVM, so people compiling with gcc will not be able to compile
> the driver for some time until the gcc support becomes better.
> 
> I think there is a way to express in Device Tree the fallback logic -

Sorry I meant 'there is NO way to express this in Device tree'

> if Rust not available then use SW PWM. So I guess the pragmatic way to
> go is to merge SW PWM temporary fix first, and later when gcc becomes
> better at compiling Rust patch it up to use HW PWM instead.
> 
>>
>> Thanks,
>> Drew
>>
>> [1] https://lore.kernel.org/linux-riscv/20250816093209.2600355-1-uwu@icenowy.me/
>>
> 
> Best regards,

Best regards,
-- 
Michal Wilczynski <m.wilczynski@samsung.com>
Re: [PATCH v14 7/7] riscv: dts: thead: Add PWM fan and thermal control
Posted by Elle Rhumsaa 1 month, 2 weeks ago 
On Wed, Aug 20, 2025 at 10:35:42AM +0200, Michal Wilczynski wrote:
> Add Device Tree nodes to enable a PWM controlled fan and it's associated
> thermal management for the Lichee Pi 4A board.
> 
> This enables temperature-controlled active cooling for the Lichee Pi 4A
> board based on SoC temperature.
> 
> Reviewed-by: Drew Fustini <fustini@kernel.org>
> Tested-by: Drew Fustini <fustini@kernel.org>
> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
> ---
>  arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts | 67 +++++++++++++++++++++++
>  1 file changed, 67 insertions(+)
> 
> diff --git a/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts b/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts
> index 4020c727f09e8e2286fdc7fecd79dbd8eba69556..c58c2085ca92a3234f1350500cedae4157f0c35f 100644
> --- a/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts
> +++ b/arch/riscv/boot/dts/thead/th1520-lichee-pi-4a.dts
> @@ -28,9 +28,76 @@ aliases {
>  	chosen {
>  		stdout-path = "serial0:115200n8";
>  	};
> +
> +	thermal-zones {
> +		cpu-thermal {
> +			polling-delay = <1000>;
> +			polling-delay-passive = <1000>;
> +			thermal-sensors = <&pvt 0>;
> +
> +			trips {
> +				fan_config0: fan-trip0 {
> +					temperature = <39000>;
> +					hysteresis = <5000>;
> +					type = "active";
> +				};
> +
> +				fan_config1: fan-trip1 {
> +					temperature = <50000>;
> +					hysteresis = <5000>;
> +					type = "active";
> +				};
> +
> +				fan_config2: fan-trip2 {
> +					temperature = <60000>;
> +					hysteresis = <5000>;
> +					type = "active";
> +				};
> +			};
> +
> +			cooling-maps {
> +				map-active-0 {
> +					cooling-device = <&fan 1 1>;
> +					trip = <&fan_config0>;
> +				};
> +
> +				map-active-1 {
> +					cooling-device = <&fan 2 2>;
> +					trip = <&fan_config1>;
> +				};
> +
> +				map-active-2 {
> +					cooling-device = <&fan 3 3>;
> +					trip = <&fan_config2>;
> +				};
> +			};
> +		};
> +	};
> +
> +	fan: pwm-fan {
> +		pinctrl-names = "default";
> +		pinctrl-0 = <&fan_pins>;
> +		compatible = "pwm-fan";
> +		#cooling-cells = <2>;
> +		pwms = <&pwm 1 10000000 0>;
> +		cooling-levels = <0 66 196 255>;
> +	};
> +
>  };
>  
>  &padctrl0_apsys {
> +	fan_pins: fan-0 {
> +		pwm1-pins {
> +			pins = "GPIO3_3"; /* PWM1 */
> +			function = "pwm";
> +			bias-disable;
> +			drive-strength = <25>;
> +			input-disable;
> +			input-schmitt-disable;
> +			slew-rate = <0>;
> +		};
> +	};
> +
>  	uart0_pins: uart0-0 {
>  		tx-pins {
>  			pins = "UART0_TXD";
> 
> -- 
> 2.34.1

Reviewed-by: Elle Rhumsaa <elle@weathered-steel.dev>

Patchew 2.1-devel-b67e4c2

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