From patchwork Sun Mar 9 12:13:20 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: John Madieu X-Patchwork-Id: 872087 Received: from relmlie6.idc.renesas.com (relmlor2.renesas.com [210.160.252.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CC9472B9A4; Sun, 9 Mar 2025 12:13:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=210.160.252.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741522424; cv=none; b=hXv0rCgO31Jy/warrl+4rGpDM+EBWClPFaDUQGA6fdnfAvrmIkAA5U3IfqsQVmAJ+lMvQQrs5CPsLu72Eqs2svPZJZ5qLH0H/uR7A79zio/G6+lSoICHdOqYgJWLlvaNU5nZJYeODSmj2g61OcJbSQCApq4EwZFDnnNwj0DDGeU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1741522424; c=relaxed/simple; bh=4DvY72QASYhj2s94IScZ3Src59yyJG6l+LyXmGolDKc=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Nj7IdHdbmW4MDbrbyxabTn4PumO2dy2iGPF5AxNBe+DzMKty2yYGTZV7A8v4LJ8KxIZKnuaAvM8KzxwIzAy4fHfpMf/Te8ZUBLSoz99NZWA676GwDw5CQ1pjp1VePog1Z+hDxTKVvfPRH5SfUotRUA7xXw8QsOmdFjMK4RKD0bg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=bp.renesas.com; spf=pass smtp.mailfrom=bp.renesas.com; arc=none smtp.client-ip=210.160.252.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=bp.renesas.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bp.renesas.com X-CSE-ConnectionGUID: 77slmj2eSVSKH9WzPWISrw== X-CSE-MsgGUID: /J4vV1yiRyuPkCfltFFj2A== Received: from unknown (HELO relmlir6.idc.renesas.com) ([10.200.68.152]) by relmlie6.idc.renesas.com with ESMTP; 09 Mar 2025 21:13:33 +0900 Received: from ubuntu.adwin.renesas.com (unknown [10.226.92.42]) by relmlir6.idc.renesas.com (Postfix) with ESMTP id 78B63422041D; Sun, 9 Mar 2025 21:13:27 +0900 (JST) From: John Madieu To: geert+renesas@glider.be, niklas.soderlund+renesas@ragnatech.se, conor+dt@kernel.org, krzk+dt@kernel.org, robh@kernel.org, rafael@kernel.org, daniel.lezcano@linaro.org Cc: magnus.damm@gmail.com, claudiu.beznea.uj@bp.renesas.com, devicetree@vger.kernel.org, john.madieu@gmail.com, rui.zhang@intel.com, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, biju.das.jz@bp.renesas.com, linux-pm@vger.kernel.org, John Madieu Subject: [RFC PATCH 0/3] thermal: Add CPU hotplug cooling driver Date: Sun, 9 Mar 2025 13:13:20 +0100 Message-ID: <20250309121324.29633-1-john.madieu.xa@bp.renesas.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-pm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit This patch series introduces a new thermal cooling driver that implements CPU hotplug-based thermal management. The driver dynamically takes CPUs offline during thermal excursions to reduce power consumption and prevent overheating, while maintaining system stability by keeping at least one CPU online. 1- Problem Statement Modern SoCs require robust thermal management to prevent overheating under heavy workloads. Existing cooling mechanisms like frequency scaling may not always provide sufficient thermal relief, especially in multi-core systems where per-core thermal contributions can be significant. 2- Solution Overview The driver: - Integrates with the Linux thermal framework as a cooling device - Registers per-CPU cooling devices that respond to thermal trip points - Uses CPU hotplug operations to reduce thermal load - Maintains system stability by preserving the boot CPU from being put offline, regardless the CPUs that are specified in cooling device list. - Implements proper state tracking and cleanup Key Features: - Dynamic CPU online/offline management based on thermal thresholds - Device tree-based configuration via thermal zones and trip points - Hysteresis support through thermal governor interactions - Safe handling of CPU state transitions during module load/unload - Compatibility with existing thermal management frameworks Testing - Verified on Renesas RZ/G3E platforms with multi-core CPU configurations - Validated thermal response using artificial load generation (emul_temp) - Confirmed proper interaction with other cooling devices - Verified support for 'plug' type trace events - Tested with step_wise governor As the 'hot' type is already used for user space notification, I've choosen 'plug' for this new type. suggestions on this are welcome. Here is an example of 'thermal-zone' that integrate 'plug' type: ``` thermal-zones { cpu-thermal { polling-delay = <1000>; polling-delay-passive = <250>; thermal-sensors = <&tsu>; cooling-maps { map0 { trip = <&target>; cooling-device = <&cpu0 0 3>, <&cpu3 0 3>; contribution = <1024>; }; map1 { trip = <&trip_emergency>; cooling-device = <&cpu1 0 1>, <&cpu2 0 1>; contribution = <1024>; }; }; trips { target: trip-point { temperature = <95000>; hysteresis = <1000>; type = "passive"; }; trip_emergency: emergency { temperature = <110000>; hysteresis = <1000>; type = "plug"; }; sensor_crit: sensor-crit { temperature = <120000>; hysteresis = <1000>; type = "critical"; }; }; }; }; ``` Dependencies - Requires standard thermal framework components (CONFIG_THERMAL) - Depends on CPU hotplug support (CONFIG_HOTPLUG_CPU) - Assumes device tree contains appropriate thermal zone definitions This series also depends upon [1], more precisely on patch 6/7, arm64: dts: renesas: r9a09g047: Add TSU node. 3) Notes for Reviewers - Focus areas: Thermal framework integration, CPU state management, and error handling - Feedback on device tree binding requirements is particularly welcome - Suggestions for interaction improvements with other governors are appreciated I look forward to your feedback and guidance on this contribution. [1] https://patchwork.kernel.org/project/linux-clk/cover/20250227122453.30480-1-john.madieu.xa@bp.renesas.com/ Regards, John John Madieu (3): thermal/cpuplog_cooling: Add CPU hotplug cooling driver tmon: Add support for THERMAL_TRIP_PLUG type arm64: dts: renesas: r9a09g047: Add thermal hotplug trip point arch/arm64/boot/dts/renesas/r9a09g047.dtsi | 13 + drivers/thermal/Kconfig | 12 + drivers/thermal/Makefile | 1 + drivers/thermal/cpuplug_cooling.c | 363 +++++++++++++++++++++ drivers/thermal/thermal_of.c | 1 + drivers/thermal/thermal_trace.h | 2 + drivers/thermal/thermal_trip.c | 1 + include/uapi/linux/thermal.h | 1 + tools/thermal/tmon/tmon.h | 1 + tools/thermal/tmon/tui.c | 3 +- 10 files changed, 397 insertions(+), 1 deletion(-) create mode 100644 drivers/thermal/cpuplug_cooling.c