From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 77A9B219FC for ; Wed, 21 Jan 2026 12:47:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=205.220.168.131 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768999661; cv=none; b=En6ieqKq1/OWWpZPQ1y5HBLlGdpnZtp1G8jT9qmmW8mDFpyjcmP2lU/I8rXJtQkn9SjLr87l1VNqvdBkhpfzAuP8N50OgFAD8BdhbLMwTFI4+Lw1U6jEA6Ntv5V4fpOgLVzx61C0icEh93MhKaLwiXF2IKQS9jKODJWUIpjASy0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768999661; c=relaxed/simple; bh=T0Kf71d6+PXT1GszsSM1KsnwWFGEsCTTiExUwxeNFlk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=ewyz+0NSFZAH9P4DchoG0WmL3hyWoUVfFMM0lpWsl74Xc8NVRDQnFFJXanJv5l1/F4+WH0TNyBFmpMUQ5y8ZsNCx2Gp7GbKaIrNeqm4Qy2FgNPLFF37J715cDu/bJXtFLI5ZH/rGvWJ1f54X3wpYmFXmc274E8x29mkvowzWbTA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com; spf=pass smtp.mailfrom=oss.qualcomm.com; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b=bBYO9xAG; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b=JnTrHv8h; arc=none smtp.client-ip=205.220.168.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.qualcomm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=qualcomm.com header.i=@qualcomm.com header.b="bBYO9xAG"; dkim=pass (2048-bit key) header.d=oss.qualcomm.com header.i=@oss.qualcomm.com header.b="JnTrHv8h" Received: from pps.filterd (m0279865.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.18.1.11/8.18.1.11) with ESMTP id 60LC4SeM2938579 for ; Wed, 21 Jan 2026 12:47:38 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=qualcomm.com; h= cc:content-transfer-encoding:content-type:date:from:in-reply-to :message-id:mime-version:references:subject:to; s=qcppdkim1; bh= HQFBthpU2DdCb+E8kQO+hSZGYuQxCuyHZ9MdH4Yo64U=; b=bBYO9xAGcN9W0iee XD+vJdjiMOC72g5CPNPk8aJgu3ATmJDNCiqIcBgZEb1Ke4I+rUUKT0lTpONQX532 hBj7S8a+k7GDH1JNArlpqdP65evucOxrS8GpVE8Gx6DxBRj9aeqW91qJxSGXrAzM /k0lfz8Du2gna9IXQIvq/KJra+/9o+5hRoE0plMareuB+B0Am6wT/t+VrTaUwhIM 6F4QjK8dxIwVg4qXLH1CB84syCycQVgC7tAQwOaSLTsqcTlkC74+lYVNJFNB53Iu VmhisefQy/ZOasQ7xon0Smm7ydBMcjCC8f37/Qj7qNw+KwDPsX3i4/fwODuEITqO eeVXhA== Received: from mail-pl1-f200.google.com (mail-pl1-f200.google.com [209.85.214.200]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 4btsmu9g2k-1 (version=TLSv1.3 cipher=TLS_AES_128_GCM_SHA256 bits=128 verify=NOT) for ; Wed, 21 Jan 2026 12:47:38 +0000 (GMT) Received: by mail-pl1-f200.google.com with SMTP id d9443c01a7336-2a76f2d7744so16064405ad.3 for ; Wed, 21 Jan 2026 04:47:38 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oss.qualcomm.com; s=google; t=1768999658; x=1769604458; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=HQFBthpU2DdCb+E8kQO+hSZGYuQxCuyHZ9MdH4Yo64U=; b=JnTrHv8hwQku2MkmFsuYWWcJnOF9vlXTmCxNGnayKVYsXd05cJgNuhO/9END08qaVk YBy0Dch+H/VinIa7xHG4LzOLAzCfra2KQXo1/zV3M1IWnq5rHdtmO/DPu4JoPmrtSmS3 aSTQT0FjWAfPh4a4fHvoL1VYLqbGFUa1XZ4TiMEwE2ts7MlyG/gHXG8rCt2Irl1wDy/q BB4vmsYj2xXisv0M+2OAKk9Z6Ox4fmUT7VbtxnNjJTXk3tzob+mGILjQ00oUfiK/QsEr HEf6asWegxj5ZDjx0yNtz+lwenLBppmXuVEpG1XgUhPctyNvjkgoylziZO8/R+RR0sk6 kv/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1768999658; x=1769604458; h=content-transfer-encoding:in-reply-to:from:content-language :references:cc:to:subject:user-agent:mime-version:date:message-id :x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=HQFBthpU2DdCb+E8kQO+hSZGYuQxCuyHZ9MdH4Yo64U=; b=R/vfSin3/sd/N5JTWgDVV4o0QBy1cFEKzpghWpM8/MsY/RC94HCveNOxws+ef/pf2r ZlfiY+fxn2Li1v6KRySZ/P0JD/cVgMCZ4hLy/5H4PIIzevIiC3/SWJ1AOmIaMe1vGLtJ s/nBeseV7z/lord0lwZMwyYGiLxnenIw4mLb3VgcVyaGbqiYPHxFCkHvj5HHwBwLUaNJ WamgKbSa01po+qtED+HvYtCWc+DTnUMuyG1rDBW3wGS/WZ+eSRktUHTpCbunfOG9kJu3 GaWh4IrlY8I8OjcSNaUjo1n6q4ASWo2u+i6+XdjW8k+NIfmXVU0k7O/f5TKAD37kThL+ abww== X-Forwarded-Encrypted: i=1; AJvYcCX39yIV1kSemUdi9c+1ETb0cJqsZi6C/6CIRIsXfnBXa9vS/nV5+OFtThTvAPnyw5dvHJHR1rv7JEyNK2NV@vger.kernel.org X-Gm-Message-State: AOJu0Yy8MOBeXJl4vjKNnHeWNi+NwcY0nhlR6Mr1hYOdqUzQTIgbfx5l qwEwmzR5Ziraq7N25PulVwnI2P9zX0cqQ+g7qsAzdGifdQxIyOjd/d81Xv6BgcenrSx+M28p5bE Yzj6mcLyFGI9MIKgpWn/6Vbf8IPpHA/hSHWY0da4O+R5H9HgUSz0qoQjjvup37KzNo3cW X-Gm-Gg: AZuq6aLWR2JzeSRSJOYkOdZKrQh3/XsE5JW2sdekS/1u21i6fQXvzZceMin00v6+R41 uRdTtWRyJjc7BvZJicyOaRYWhqVsCAdac7s82nXTDBYTzVQ5v/DLe86VIbKdhUb17lHJAZH+vZo INsHZ8ZD2ibbao4Vjj2Oe636moJKDx+Y/XnkHRxsP6cm3KRcnBKsd6m7oDO297MZzQRCPlSmLL2 c3GGDnwntMWdEQKzoSPIVXAVUEahTcZ+7NFNf6Qi/7SZ8ZQXa+q5DXJBQ38c2kDM9vgQ2w6oaXl 0u9PuzSFf7nJu3tNDq18bPc7rSzvUoOQDGGev3UwcfBP0soMM5EB8X2IEu9w2yIcy3NI5F1I85D rxL3P6DNXAsUKMdo/aY716CLN/tT+7RzS X-Received: by 2002:a17:902:f548:b0:29f:cb81:8bd1 with SMTP id d9443c01a7336-2a76b2697demr49338475ad.55.1768999657695; Wed, 21 Jan 2026 04:47:37 -0800 (PST) X-Received: by 2002:a17:902:f548:b0:29f:cb81:8bd1 with SMTP id d9443c01a7336-2a76b2697demr49338235ad.55.1768999657155; Wed, 21 Jan 2026 04:47:37 -0800 (PST) Received: from [10.206.103.12] ([202.46.23.25]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2a780a4631csm37773775ad.18.2026.01.21.04.47.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 21 Jan 2026 04:47:36 -0800 (PST) Message-ID: Date: Wed, 21 Jan 2026 18:17:31 +0530 Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/2] arm64: dts: qcom: SM8750: Enable CPUFreq support To: Konrad Dybcio , Jagadeesh Kona Cc: Ajit Pandey , Imran Shaik , Taniya Das , linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, Sibi Sankar , Jassi Brar , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Bjorn Andersson , Konrad Dybcio References: <20251211-sm8750-cpufreq-v1-0-394609e8d624@oss.qualcomm.com> <20251211-sm8750-cpufreq-v1-2-394609e8d624@oss.qualcomm.com> <908b64f1-f6ac-4c5e-9c72-1174cba62017@oss.qualcomm.com> <99796cc0-f29b-40d0-b8bb-ebcbcc950b23@oss.qualcomm.com> <996f47de-5900-4a3a-9372-e5ea3ae31c8b@oss.qualcomm.com> <417f77ba-a0b0-4ba5-824d-8814b776c557@oss.qualcomm.com> Content-Language: en-US From: Akhil P Oommen In-Reply-To: <417f77ba-a0b0-4ba5-824d-8814b776c557@oss.qualcomm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Authority-Analysis: v=2.4 cv=OaiVzxTY c=1 sm=1 tr=0 ts=6970caea cx=c_pps a=IZJwPbhc+fLeJZngyXXI0A==:117 a=ZePRamnt/+rB5gQjfz0u9A==:17 a=IkcTkHD0fZMA:10 a=vUbySO9Y5rIA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=EUspDBNiAAAA:8 a=hfhOgts8FtG9wfp3ybAA:9 a=QEXdDO2ut3YA:10 a=uG9DUKGECoFWVXl0Dc02:22 X-Proofpoint-GUID: 9rgW1BYqQTDbpEdy-Xj27uwthBN4qt13 X-Proofpoint-ORIG-GUID: 9rgW1BYqQTDbpEdy-Xj27uwthBN4qt13 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwMTIxMDEwNyBTYWx0ZWRfX8cEdLfSVoz77 9fT3Cp/a60/iHruzKe+y9fk/Dgd4f0j6WrOEHeXxMHhIoLQgVeIQS5CywrngcCmRSLeGReUrm6W QavrwyqdHNkw67zYGFz13kG71ftzIfh+OM9ZGi9vbG26/Ez/TFIsfGk2/taM+igLCcPvgAHkW1V RO7Ox1GpQDHcyCbhnKV2c7catQtSfr0UcO5jFhXSL7gvL+quPGUSxMMxDR99c2OGE6asgtbsS84 y238BSR1660Syw4jBYVhovKGxJkZJPavmoqPO3b1WseNYB+IpZemJgMfXihauRaHZhf9E47kfBu iJq+W4fEvw9NQNLfsqpieBaodf6vXj4DHeN8mf/lZIGPheJV34/kwC8pVLjaEqvgoOwkw46LvLM 8SM02Qciw1Ki9Br5rEi2Dx0/Mxtfr0lXvoTcEFrLhosZI+C7YwezVNM0x0Wldw0ZarRwUHfpu5d sr1sbQIijE+Y4LWHKHA== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1121,Hydra:6.1.20,FMLib:17.12.100.49 definitions=2026-01-21_01,2026-01-20_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 bulkscore=0 impostorscore=0 suspectscore=0 adultscore=0 spamscore=0 lowpriorityscore=0 phishscore=0 priorityscore=1501 clxscore=1015 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2601210107 On 1/21/2026 5:06 PM, Konrad Dybcio wrote: > On 1/20/26 9:54 PM, Akhil P Oommen wrote: >> On 1/20/2026 8:13 PM, Konrad Dybcio wrote: >>> On 1/20/26 12:25 PM, Akhil P Oommen wrote: >>>> On 1/20/2026 3:44 PM, Konrad Dybcio wrote: >>>>> On 1/19/26 8:00 PM, Akhil P Oommen wrote: >>>>>> On 12/11/2025 12:32 AM, Jagadeesh Kona wrote: >>>>>>> Add the cpucp mailbox, sram and SCMI nodes required to enable >>>>>>> the CPUFreq support using the SCMI perf protocol on SM8750 SoCs. >>>>>>> >>>>>>> Signed-off-by: Jagadeesh Kona >>>>>> >>>>>> Just curious, does this patch enable thermal mitigation for CPU clusters >>>>>> too? >>>>> >>>>> If nothing changed, we have lets-not-explode type mitigations via LMH, >>>>> but lets-not-burn-the-user would require a skin temp sensor to be >>>>> wired up, which then could be used to enable some cooling action >>>> >>>> In some chipsets, I have noticed that the gpu cooling device throttles >>>> GPU to the lowest OPP even with not-so-heavy GPU workloads, making it >>>> unusable-ly slow. My hypothesis was that it was due to unmitigated CPU >>>> temperature tripping up GPU Tsens. >>>> >>>> So, I am wondering if there are any additional CPU cooling related >>>> changes required to get a reasonable overall performance under thermal >>>> constraints. >>> >>> Yes, something like the aforementioned skin-temp sensor at least.. >> >> I suppose this sensor is off-chip and slow to react. > > Yes, this would be placed somewhere on the chassis of the device to > reflect the actual temperature that the user could experience (since > there are regulations about maximum values of that) > >>> Today Linux will not throttle the CPUs at all (they're not even declared >>> as cooling devices) and we sorta agreed that in general it's a good thing >>> (tm), because otherwise we'd be coding in a cooling profile into the SoC >>> DTSI without taking into account the cooling capabilities of a given end >>> device (i.e. in an extreme case, a PC with SM8650 with a cooler that's >>> 3kg of aluminium vs a Steam Frame headset where the SoC is centimeters >>> away from your face) >>> >>> Currently, we have cooling policies for devices with fans and the only >>> other action is based on a skin temperature sensor (sc8280xp + x13s). >>> Everything else is left up to the LMH defaults. AFAIK work is ongoing to >>> create a more informed solution, that would have to (quite obviously) >>> live in userland. >> >> I can understand that the skin-temp based mitigation is influenced by >> various design decision outside of the SoC die. But I think there should >> an on-chip sensor based mitigation which is fast and usually for a short >> duration which helps to avoid extreme temperature or violating the >> maximum operating point of the chipset. I guess it should depend only on >> the SoC characteristics as it is a last resort. It may be implemented in >> SW (like cooling device for Adreno GPU) or in HW. Probably the LMH >> hardware you mentioned offers this functionality for CPU clusters. I >> have no clue. :( > > Yes, the CPUs are covered. Does this LMH based thermal migitation require any initialization from Linux? If yes, could you please share a link to a patch which enables it for any recent chipset for my reference? -Akhil. > >> I am hoping that if this on-chip mitigation is enabled and wired up >> correctly for CPU clusters (probably DDR too), it would reduce the >> unnecessary thermal trips on GPU Tsens and help to reach a performance >> equilibrium which is reasonably good. > > Today, the OS is unaware that it can throttle anything else than the > GPU, so in its view that's the reasonable step to take. Further, any > device it knows how to throttle, it'll do so in a very jittery fashion > where it crosses the threshold, gets slowed down, cools a bit, gets > unthrottled, heats back up, rinse and repeat (because the cooling > solution of almost any form-factor is not capable of sustaining a > 100%usage workload for long) > > Konrad