From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id C3836D767C3 for ; Fri, 19 Dec 2025 10:28:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=jWzAK4DRMOzi/z58HnevXQUOYdKr+tJ7WarNZsTc1VE=; b=x9B+dLea50Vo9BkZHh467RcCIc fnKcA7Ibs5mxUzC/6wHOA5Cn2fIQdVN7FGQMkPW5pLWvqN9hm3tO4ssKR8dWvqQaanx6CJic0iEe9 NYDPfmQ/m3/o9KZxQpiW3UPg+lMhmfpf7bfTsouIuzl4nmCta4cA0qgDSB2MUSUhvze/P5+hN0EiI FiyrD5ZK+gGItmZzc9anj1ZvCx/hcKlJVHK7DVC6pn0pYVHYY9u/jNZIrI+/+GF5cGfjLc4J4+VBr +xxlzc6t/4JVKpUfyC/hDuuMcVBGYmXvWc/D2MrBeuVRB32VNWkwdVdAd/9rysMLAE4WvH0AoKDas 2ojxoG9w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vWXiT-0000000A4V7-1nJK; Fri, 19 Dec 2025 10:28:09 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vWXiQ-0000000A4UX-3OHT for linux-arm-kernel@lists.infradead.org; Fri, 19 Dec 2025 10:28:07 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 61753106F; Fri, 19 Dec 2025 02:27:58 -0800 (PST) Received: from [10.1.197.1] (ewhatever.cambridge.arm.com [10.1.197.1]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 34BA43F5CA; Fri, 19 Dec 2025 02:28:03 -0800 (PST) Message-ID: Date: Fri, 19 Dec 2025 10:28:01 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 00/12] coresight: Add CPU cluster funnel/replicator/tmc support To: Sudeep Holla , yuanfang zhang Cc: Mike Leach , James Clark , Rob Herring , Krzysztof Kozlowski , Conor Dooley , Mathieu Poirier , Leo Yan , Alexander Shishkin , Bjorn Andersson , Konrad Dybcio , kernel@oss.qualcomm.com, coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, maulik.shah@oss.qualcomm.com, Jie Gan References: <20251218-cpu_cluster_component_pm-v2-0-2335a6ae62a0@oss.qualcomm.com> <20251218-careful-ruby-wildebeest-a8babd@sudeepholla> <20251219-hysterical-sparkling-meerkat-59c5eb@sudeepholla> Content-Language: en-US From: Suzuki K Poulose In-Reply-To: <20251219-hysterical-sparkling-meerkat-59c5eb@sudeepholla> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251219_022806_889460_D5621462 X-CRM114-Status: GOOD ( 20.01 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 19/12/2025 10:21, Sudeep Holla wrote: > On Fri, Dec 19, 2025 at 10:13:14AM +0800, yuanfang zhang wrote: >> >> >> On 12/18/2025 7:33 PM, Sudeep Holla wrote: >>> On Thu, Dec 18, 2025 at 12:09:40AM -0800, Yuanfang Zhang wrote: >>>> This patch series adds support for CoreSight components local to CPU clusters, >>>> including funnel, replicator, and TMC, which reside within CPU cluster power >>>> domains. These components require special handling due to power domain >>>> constraints. >>>> >>> >>> Could you clarify why PSCI-based power domains associated with clusters in >>> domain-idle-states cannot address these requirements, given that PSCI CPU-idle >>> OSI mode was originally intended to support them? My understanding of this >>> patch series is that OSI mode is unable to do so, which, if accurate, appears >>> to be a flaw that should be corrected. >> >> It is due to the particular characteristics of the CPU cluster power >> domain.Runtime PM for CPU devices works little different, it is mostly used >> to manage hierarchicalCPU topology (PSCI OSI mode) to talk with genpd >> framework to manage the last CPU handling in cluster. > > That is indeed the intended design. Could you clarify which specific > characteristics differentiate it here? > >> It doesn’t really send IPI to wakeup CPU device (It don’t have >> .power_on/.power_off) callback implemented which gets invoked from >> .runtime_resume callback. This behavior is aligned with the upstream Kernel. >> > > I am quite lost here. Why is it necessary to wake up the CPU? If I understand > correctly, all of this complexity is meant to ensure that the cluster power > domain is enabled before any of the funnel registers are accessed. Is that > correct? > > If so, and if the cluster domains are already defined as the power domains for > these funnel devices, then they should be requested to power on automatically > before any register access occurs. Is that not the case? > > What am I missing in this reasoning? Exactly, this is what I am too. But then you get the "pre-formated standard response" without answering our questions. Suzuki