[v3] Add TH1520 GPU support with power sequencing

[PATCH v3 6/8] riscv: dts: thead: Add GPU power sequencer node

Posted by Michal Wilczynski 8 months, 2 weeks ago

Add the device tree node for the T-HEAD TH1520 GPU power sequencer
(gpu_pwrseq) to the th1520.dtsi file.

This node instantiates the thead,th1520-gpu-pwrseq driver, which
is responsible for managing the GPU's power-on/off sequence. The node
specifies the gpu-clkgen reset, which is one of the resources
controlled by this sequencer.

Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
---
 arch/riscv/boot/dts/thead/th1520.dtsi | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/riscv/boot/dts/thead/th1520.dtsi b/arch/riscv/boot/dts/thead/th1520.dtsi
index bdbb1b985b0b76cf669a9bf40c6ec37258329056..6170eec79e919b606a2046ac8f52db07e47ef441 100644
--- a/arch/riscv/boot/dts/thead/th1520.dtsi
+++ b/arch/riscv/boot/dts/thead/th1520.dtsi
@@ -238,6 +238,12 @@ aon: aon {
 		#power-domain-cells = <1>;
 	};
 
+	gpu_pwrseq: pwrseq {
+		compatible = "thead,th1520-gpu-pwrseq";
+		resets = <&rst TH1520_RESET_ID_GPU_CLKGEN>;
+		reset-names = "gpu-clkgen";
+	};
+
 	soc {
 		compatible = "simple-bus";
 		interrupt-parent = <&plic>;

-- 
2.34.1

Re: [PATCH v3 6/8] riscv: dts: thead: Add GPU power sequencer node

Posted by Krzysztof Kozlowski 8 months, 1 week ago

On Fri, May 30, 2025 at 12:23:53AM GMT, Michal Wilczynski wrote:
> Add the device tree node for the T-HEAD TH1520 GPU power sequencer
> (gpu_pwrseq) to the th1520.dtsi file.
> 
> This node instantiates the thead,th1520-gpu-pwrseq driver, which

Explain the hardware, not what drivers do.

> is responsible for managing the GPU's power-on/off sequence. The node
> specifies the gpu-clkgen reset, which is one of the resources
> controlled by this sequencer.
> 
> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
> ---
>  arch/riscv/boot/dts/thead/th1520.dtsi | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/riscv/boot/dts/thead/th1520.dtsi b/arch/riscv/boot/dts/thead/th1520.dtsi
> index bdbb1b985b0b76cf669a9bf40c6ec37258329056..6170eec79e919b606a2046ac8f52db07e47ef441 100644
> --- a/arch/riscv/boot/dts/thead/th1520.dtsi
> +++ b/arch/riscv/boot/dts/thead/th1520.dtsi
> @@ -238,6 +238,12 @@ aon: aon {
>  		#power-domain-cells = <1>;
>  	};
>  
> +	gpu_pwrseq: pwrseq {

Node names should be generic. See also an explanation and list of
examples (not exhaustive) in DT specification:
https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-basics.html#generic-names-recommendation

> +		compatible = "thead,th1520-gpu-pwrseq";
> +		resets = <&rst TH1520_RESET_ID_GPU_CLKGEN>;
> +		reset-names = "gpu-clkgen";

What is the point of pwrseq if there is no consumer/user of it? Looks
like simple placeholder and anyway maybe the future consumer should just
use reset directly.

Best regards,
Krzysztof

Re: [PATCH v3 6/8] riscv: dts: thead: Add GPU power sequencer node

Posted by Michal Wilczynski 8 months, 1 week ago


On 6/3/25 15:22, Krzysztof Kozlowski wrote:
> On Fri, May 30, 2025 at 12:23:53AM GMT, Michal Wilczynski wrote:
>> Add the device tree node for the T-HEAD TH1520 GPU power sequencer
>> (gpu_pwrseq) to the th1520.dtsi file.
>>
>> This node instantiates the thead,th1520-gpu-pwrseq driver, which
> 
> Explain the hardware, not what drivers do.
> 
>> is responsible for managing the GPU's power-on/off sequence. The node
>> specifies the gpu-clkgen reset, which is one of the resources
>> controlled by this sequencer.
>>
>> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
>> ---
>>  arch/riscv/boot/dts/thead/th1520.dtsi | 6 ++++++
>>  1 file changed, 6 insertions(+)
>>
>> diff --git a/arch/riscv/boot/dts/thead/th1520.dtsi b/arch/riscv/boot/dts/thead/th1520.dtsi
>> index bdbb1b985b0b76cf669a9bf40c6ec37258329056..6170eec79e919b606a2046ac8f52db07e47ef441 100644
>> --- a/arch/riscv/boot/dts/thead/th1520.dtsi
>> +++ b/arch/riscv/boot/dts/thead/th1520.dtsi
>> @@ -238,6 +238,12 @@ aon: aon {
>>  		#power-domain-cells = <1>;
>>  	};
>>  
>> +	gpu_pwrseq: pwrseq {
> 
> Node names should be generic. See also an explanation and list of
> examples (not exhaustive) in DT specification:
> https://protect2.fireeye.com/v1/url?k=a53ea5d3-c4434f50-a53f2e9c-74fe48600158-c81092475ef416b3&q=1&e=d333d06b-0b06-493e-a358-e29ca542dfe7&u=https%3A%2F%2Fdevicetree-specification.readthedocs.io%2Fen%2Flatest%2Fchapter2-devicetree-basics.html%23generic-names-recommendation
> 
>> +		compatible = "thead,th1520-gpu-pwrseq";
>> +		resets = <&rst TH1520_RESET_ID_GPU_CLKGEN>;
>> +		reset-names = "gpu-clkgen";
> 
> What is the point of pwrseq if there is no consumer/user of it? Looks
> like simple placeholder and anyway maybe the future consumer should just
> use reset directly.

Yeah I think you're right, I wanted to explore adding the pwrseq
provider in separate node per discussion in v2 [1]. But for the v4 I
think I'll revert to the v2 way of handling this reset [2].

[1] - https://lore.kernel.org/all/CAPDyKFpi6_CD++a9sbGBvJCuBSQS6YcpNttkRQhQMTWy1yyrRg@mail.gmail.com/
[2] - https://lore.kernel.org/all/20250414-apr_14_for_sending-v2-2-70c5af2af96c@samsung.com/

> 
> Best regards,
> Krzysztof
> 
> 

Best regards,
-- 
Michal Wilczynski <m.wilczynski@samsung.com>

Re: [PATCH v3 6/8] riscv: dts: thead: Add GPU power sequencer node

Posted by Bartosz Golaszewski 8 months, 1 week ago

On Tue, Jun 3, 2025 at 8:45 PM Michal Wilczynski
<m.wilczynski@samsung.com> wrote:
>
>
>
> On 6/3/25 15:22, Krzysztof Kozlowski wrote:
> > On Fri, May 30, 2025 at 12:23:53AM GMT, Michal Wilczynski wrote:
> >> Add the device tree node for the T-HEAD TH1520 GPU power sequencer
> >> (gpu_pwrseq) to the th1520.dtsi file.
> >>
> >> This node instantiates the thead,th1520-gpu-pwrseq driver, which
> >
> > Explain the hardware, not what drivers do.
> >
> >> is responsible for managing the GPU's power-on/off sequence. The node
> >> specifies the gpu-clkgen reset, which is one of the resources
> >> controlled by this sequencer.
> >>
> >> Signed-off-by: Michal Wilczynski <m.wilczynski@samsung.com>
> >> ---
> >>  arch/riscv/boot/dts/thead/th1520.dtsi | 6 ++++++
> >>  1 file changed, 6 insertions(+)
> >>
> >> diff --git a/arch/riscv/boot/dts/thead/th1520.dtsi b/arch/riscv/boot/dts/thead/th1520.dtsi
> >> index bdbb1b985b0b76cf669a9bf40c6ec37258329056..6170eec79e919b606a2046ac8f52db07e47ef441 100644
> >> --- a/arch/riscv/boot/dts/thead/th1520.dtsi
> >> +++ b/arch/riscv/boot/dts/thead/th1520.dtsi
> >> @@ -238,6 +238,12 @@ aon: aon {
> >>              #power-domain-cells = <1>;
> >>      };
> >>
> >> +    gpu_pwrseq: pwrseq {
> >
> > Node names should be generic. See also an explanation and list of
> > examples (not exhaustive) in DT specification:
> > https://protect2.fireeye.com/v1/url?k=a53ea5d3-c4434f50-a53f2e9c-74fe48600158-c81092475ef416b3&q=1&e=d333d06b-0b06-493e-a358-e29ca542dfe7&u=https%3A%2F%2Fdevicetree-specification.readthedocs.io%2Fen%2Flatest%2Fchapter2-devicetree-basics.html%23generic-names-recommendation
> >
> >> +            compatible = "thead,th1520-gpu-pwrseq";
> >> +            resets = <&rst TH1520_RESET_ID_GPU_CLKGEN>;
> >> +            reset-names = "gpu-clkgen";
> >
> > What is the point of pwrseq if there is no consumer/user of it? Looks
> > like simple placeholder and anyway maybe the future consumer should just
> > use reset directly.
>
> Yeah I think you're right, I wanted to explore adding the pwrseq
> provider in separate node per discussion in v2 [1]. But for the v4 I
> think I'll revert to the v2 way of handling this reset [2].
>
> [1] - https://lore.kernel.org/all/CAPDyKFpi6_CD++a9sbGBvJCuBSQS6YcpNttkRQhQMTWy1yyrRg@mail.gmail.com/
> [2] - https://lore.kernel.org/all/20250414-apr_14_for_sending-v2-2-70c5af2af96c@samsung.com/
>

I think you still need to connect the GPU node with its pwrseq
provider (which will be the aon node in this case). But you already
have this link - the aon power domain. You can parse it in the pwrseq
match callback to determine which GPU is powered by which AON module.

Bart