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 264DACCF9E3 for ; Tue, 11 Nov 2025 10:18:17 +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:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=mZtzKsYKXuyZOjPqT7ixJbnhG4D+CsUiH+r4jEbNTKM=; b=k2+eV1/ebUJUVeHLtYEBF6mFVj +RxQh3CziAZE02KQu0hlhORhreCVumjvzlNZVOIfHFETvnFiGNdok5eJtYW5q5XS1P3hpbUDqWjkZ HUpLARP0TQhoGhfdqQvoxKmjB3os+9jMFFesYYVTYXGDp72R2OkrmgQ5OHrn/XldqdIuHyY134IFt XX30ETJycZO4UMVKTrnA83ZPyxGhXSjoLxwTXFwZ2YGjsnRdc0VcHe0tkZG3wELLEv8yAsJgi+0rv 29x2bG7Z+v0+E7pEb6eacm7j4kPjeiHy/0tT9YR7/1rmY+XDjBeFt4MoaFOAMmlFDAttVajm7AHCd GZpWahEw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vIlRz-00000006vyK-17oE; Tue, 11 Nov 2025 10:18:11 +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 1vIlRx-00000006vxv-0p30 for linux-arm-kernel@lists.infradead.org; Tue, 11 Nov 2025 10:18:10 +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 702DB2F; Tue, 11 Nov 2025 02:18:00 -0800 (PST) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id BA2843F63F; Tue, 11 Nov 2025 02:18:07 -0800 (PST) Date: Tue, 11 Nov 2025 10:18:05 +0000 From: Leo Yan To: Suzuki K Poulose Cc: Mike Leach , James Clark , Yeoreum Yun , Greg Kroah-Hartman , Alexander Shishkin , Yabin Cui , Keita Morisaki , Yuanfang Zhang , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v5 09/11] coresight: etm4x: Add flag to control single-shot restart Message-ID: <20251111101805.GD281971@e132581.arm.com> References: <20251103-arm_coresight_power_management_fix-v5-0-f803c19aa153@arm.com> <20251103-arm_coresight_power_management_fix-v5-9-f803c19aa153@arm.com> <20251111092403.GB281971@e132581.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251111_021809_294487_F61F2FD9 X-CRM114-Status: GOOD ( 11.96 ) 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 Tue, Nov 11, 2025 at 09:43:13AM +0000, Suzuki Kuruppassery Poulose wrote: [...] > > if (!is_idle_task(current)) { > > if (config->ss_ctrl[i] || config->ss_pe_cmp[i]) > > config->ss_status[i] &= ~TRCSSCSRn_STATUS; > > } > > What happens when we do a system wide session and a CPU is running an > idle task ? For a system wide trace, the ETM device is enabled and disabled by the perf when the session start and finish. During the session: - If CPU off states are not enabled, nothing will happen in idle threads, as no CPU PM notifier will be invoked. - If CPU off states have been enabled, CPU PM notifier will save and restore ETM device context, and keep single-shot status. This is same with current save/restore flow. I don't see any issue for this. Thanks, Leo