Re: [PATCH v2 2/2] arm64: dts: qcom: sm8650: setup gpu thermal with higher temperatures

[Akhil P Oommen <quic_akhilpo@quicinc.com>]

On 1/10/2025 4:06 PM, Neil Armstrong wrote:
> On the SM8650, the dynamic clock and voltage scaling (DCVS) for the GPU
> is done in an hardware controlled loop by the GPU Management Unit (GMU).
> 
> Since the GMU does a better job at maintaining the GPUs temperature in an
> acceptable range by taking in account more parameters like the die
> characteristics or other internal sensors, it makes no sense to try
> and reproduce a similar set of constraints with the Linux devfreq thermal
> core.

Just FYI, this description is incorrect. SM8650's GMU doesn't do any
sort of thermal management.

-Akhil.

> 
> Instead, set higher temperatures in the GPU trip points corresponding to
> the temperatures provided by Qualcomm in the dowstream source, which will
> trigger the devfreq thermal core if the GMU cannot handle the temperature
> surge, and try our best to avoid reaching the critical temperature trip
> point which should trigger an inevitable thermal shutdown.
> 
> Fixes: 497624ed5506 ("arm64: dts: qcom: sm8650: Throttle the GPU when overheating")
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> ---
>  arch/arm64/boot/dts/qcom/sm8650.dtsi | 48 ++++++++++++++++++------------------
>  1 file changed, 24 insertions(+), 24 deletions(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sm8650.dtsi b/arch/arm64/boot/dts/qcom/sm8650.dtsi
> index 95509ce2713d4fcc3dbe0c5cd5827312d5681af4..e9fcf05cb084b7979ecf0f4712fed332e9f4b07a 100644
> --- a/arch/arm64/boot/dts/qcom/sm8650.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sm8650.dtsi
> @@ -6173,19 +6173,19 @@ map0 {
>  
>  			trips {
>  				gpu0_alert0: trip-point0 {
> -					temperature = <85000>;
> +					temperature = <95000>;
>  					hysteresis = <1000>;
>  					type = "passive";
>  				};
>  
>  				trip-point1 {
> -					temperature = <90000>;
> +					temperature = <115000>;
>  					hysteresis = <1000>;
>  					type = "hot";
>  				};
>  
>  				trip-point2 {
> -					temperature = <110000>;
> +					temperature = <125000>;
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
> @@ -6206,19 +6206,19 @@ map0 {
>  
>  			trips {
>  				gpu1_alert0: trip-point0 {
> -					temperature = <85000>;
> +					temperature = <95000>;
>  					hysteresis = <1000>;
>  					type = "passive";
>  				};
>  
>  				trip-point1 {
> -					temperature = <90000>;
> +					temperature = <115000>;
>  					hysteresis = <1000>;
>  					type = "hot";
>  				};
>  
>  				trip-point2 {
> -					temperature = <110000>;
> +					temperature = <125000>;
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
> @@ -6239,19 +6239,19 @@ map0 {
>  
>  			trips {
>  				gpu2_alert0: trip-point0 {
> -					temperature = <85000>;
> +					temperature = <95000>;
>  					hysteresis = <1000>;
>  					type = "passive";
>  				};
>  
>  				trip-point1 {
> -					temperature = <90000>;
> +					temperature = <115000>;
>  					hysteresis = <1000>;
>  					type = "hot";
>  				};
>  
>  				trip-point2 {
> -					temperature = <110000>;
> +					temperature = <125000>;
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
> @@ -6272,19 +6272,19 @@ map0 {
>  
>  			trips {
>  				gpu3_alert0: trip-point0 {
> -					temperature = <85000>;
> +					temperature = <95000>;
>  					hysteresis = <1000>;
>  					type = "passive";
>  				};
>  
>  				trip-point1 {
> -					temperature = <90000>;
> +					temperature = <115000>;
>  					hysteresis = <1000>;
>  					type = "hot";
>  				};
>  
>  				trip-point2 {
> -					temperature = <110000>;
> +					temperature = <125000>;
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
> @@ -6305,19 +6305,19 @@ map0 {
>  
>  			trips {
>  				gpu4_alert0: trip-point0 {
> -					temperature = <85000>;
> +					temperature = <95000>;
>  					hysteresis = <1000>;
>  					type = "passive";
>  				};
>  
>  				trip-point1 {
> -					temperature = <90000>;
> +					temperature = <115000>;
>  					hysteresis = <1000>;
>  					type = "hot";
>  				};
>  
>  				trip-point2 {
> -					temperature = <110000>;
> +					temperature = <125000>;
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
> @@ -6338,19 +6338,19 @@ map0 {
>  
>  			trips {
>  				gpu5_alert0: trip-point0 {
> -					temperature = <85000>;
> +					temperature = <95000>;
>  					hysteresis = <1000>;
>  					type = "passive";
>  				};
>  
>  				trip-point1 {
> -					temperature = <90000>;
> +					temperature = <115000>;
>  					hysteresis = <1000>;
>  					type = "hot";
>  				};
>  
>  				trip-point2 {
> -					temperature = <110000>;
> +					temperature = <125000>;
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
> @@ -6371,19 +6371,19 @@ map0 {
>  
>  			trips {
>  				gpu6_alert0: trip-point0 {
> -					temperature = <85000>;
> +					temperature = <95000>;
>  					hysteresis = <1000>;
>  					type = "passive";
>  				};
>  
>  				trip-point1 {
> -					temperature = <90000>;
> +					temperature = <115000>;
>  					hysteresis = <1000>;
>  					type = "hot";
>  				};
>  
>  				trip-point2 {
> -					temperature = <110000>;
> +					temperature = <125000>;
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
> @@ -6404,19 +6404,19 @@ map0 {
>  
>  			trips {
>  				gpu7_alert0: trip-point0 {
> -					temperature = <85000>;
> +					temperature = <95000>;
>  					hysteresis = <1000>;
>  					type = "passive";
>  				};
>  
>  				trip-point1 {
> -					temperature = <90000>;
> +					temperature = <115000>;
>  					hysteresis = <1000>;
>  					type = "hot";
>  				};
>  
>  				trip-point2 {
> -					temperature = <110000>;
> +					temperature = <125000>;
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
>