linux-kernel - Re: [PATCH v1 6/8] arm64: dts: qcom: Enable cdsp qmi tmd devices for talos

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Message-ID: <cnihk2656pi2qpag3gchf7csfkcj6otkwemcnb5cqo62cymtzx@23hjt6pjjhpx>
Date: Sat, 3 Jan 2026 09:13:57 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Gaurav Kohli <gaurav.kohli@....qualcomm.com>
Cc: mathieu.poirier@...aro.org, robh@...nel.org, krzk+dt@...nel.org, 
	conor+dt@...nel.org, rafael@...nel.org, daniel.lezcano@...aro.org, 
	rui.zhang@...el.com, lukasz.luba@....com, konradybcio@...nel.org, amitk@...nel.org, 
	mani@...nel.org, casey.connolly@...aro.org, linux-arm-msm@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v1 6/8] arm64: dts: qcom: Enable cdsp qmi tmd devices for
 talos

On Tue, Dec 23, 2025 at 06:02:25PM +0530, Gaurav Kohli wrote:
> Enable cdsp cooling devices and thermal zone cooling map bindings
> for cdsp.

This is the first time we're seeing this in a DeviceTree file, so I want
a proper problem description of what it is, why it is. As described in:
https://docs.kernel.org/process/submitting-patches.html#describe-your-changes

> 
> Signed-off-by: Gaurav Kohli <gaurav.kohli@....qualcomm.com>
> ---
>  arch/arm64/boot/dts/qcom/talos.dtsi | 23 +++++++++++++++++++++++
>  1 file changed, 23 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/qcom/talos.dtsi b/arch/arm64/boot/dts/qcom/talos.dtsi
> index 95d26e313622..61faea81c263 100644
> --- a/arch/arm64/boot/dts/qcom/talos.dtsi
> +++ b/arch/arm64/boot/dts/qcom/talos.dtsi
> @@ -18,6 +18,7 @@
>  #include <dt-bindings/power/qcom-rpmpd.h>
>  #include <dt-bindings/power/qcom,rpmhpd.h>
>  #include <dt-bindings/soc/qcom,rpmh-rsc.h>
> +#include <dt-bindings/thermal/thermal.h>
>  
>  / {
>  	interrupt-parent = <&intc>;
> @@ -3550,6 +3551,14 @@ compute-cb@6 {
>  					};
>  				};
>  			};
> +
> +			cooling {
> +				compatible = "qcom,qmi-cooling-cdsp";
> +					cdsp_sw: cdsp_sw {
> +						label = "cdsp_sw";
> +						#cooling-cells = <2>;
> +					};
> +			};
>  		};
>  
>  		pmu@...6300 {
> @@ -4721,12 +4730,26 @@ q6-hvx-thermal {
>  			thermal-sensors = <&tsens0 10>;
>  
>  			trips {
> +				q6_hvx_alert0: trip-point0 {
> +					temperature = <105000>;

Perhaps my coffee hasn't kicked in this morning, but doesn't this say
that we should start throttle at 105C? Isn't that quite a bit above the
point where the OSM/EPSS is starving the apps CPUs? Shouldn't it be the
other way around? What does this cooling device actually do?

Regards,
Bjorn

> +					hysteresis = <5000>;
> +					type = "passive";
> +				};
> +
>  				q6-hvx-critical {
>  					temperature = <115000>;
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
>  			};
> +
> +			cooling-maps {
> +				map0 {
> +					trip = <&q6_hvx_alert0>;
> +					cooling-device = <&cdsp_sw
> +							THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
> +				};
> +			};
>  		};
>  
>  		mdm-core-thermal {
> -- 
> 2.34.1
>