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 8B754C369DC for ; Mon, 28 Apr 2025 13:29:15 +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: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=Q8lp5UrUp+XdpwqCCx1TxDIQu5ltAd7kTY6JKNYmfio=; b=hY0ERlU2RGae/tRWBV+HgC9Iaa zgZi+RCk4rWpD/lNm6WdrVvvzI3RglLJbxHusYALEYCdGjuy1vSVBDFDRqpQD27eopk8GCkKGh3xJ MDVyyD+zfPB8FhiTHvsdSUsE4VNCIYbxxfLdpS9iVZtT7fA5Umi+il0Cm3+vDN7f0X5RzoJsVs/VY Y3qCPu4UBC4R+fXhDxS6GVCjkBbm8e/CakG9puQvX7RR8xhLvJq5eTQwZlVnIzP4W4OUzTnY9oce1 KQyip0CQ/ZkQ2m3YCGJZg/ktMUZTFUZPj7yomspcwPj2L0ztZcca9aWB7QeWSfe7qbrev+T1sSKrs F9aAelHQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u9OXi-00000006TyB-0bXg; Mon, 28 Apr 2025 13:29:06 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1u9OBD-00000006LSe-0kuc for linux-arm-kernel@bombadil.infradead.org; Mon, 28 Apr 2025 13:05:51 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Q8lp5UrUp+XdpwqCCx1TxDIQu5ltAd7kTY6JKNYmfio=; b=F4p8K4X7Wvd1p/zxoqz2lg4cX9 g+buQgW7LC7Ipq3/UyUq8IBt7KZpvCiSWDT2YYnY60M8eMxYTdIbQmljDlo/ZWME2Vv3kJtT0znCg d4wPJfZQEcBDEVXtJfzGu4rvFWA6TTWidT38Q667Ty09e7AEmmlLRpshoWUe7TTGDCpziQsGyakEY DioV2vjjvlxfAQnZ9SmQKe+ba/HLibbh5xHn04FJISNV5ZeDh+mNE7MVFjSCHTEI4HL50EoIoWz68 hdmzmgC6RE+EPgrKds1urPe57FqBsukN+WOue0WM8Du7sMdDpnPqC240sJLP3az4CG7SEDDRyXYQm AkIQ/MXw==; Received: from foss.arm.com ([217.140.110.172]) by casper.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1u9OAw-0000000HRCA-15NH for linux-arm-kernel@lists.infradead.org; Mon, 28 Apr 2025 13:05:43 +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 BBF6F1516; Mon, 28 Apr 2025 06:05:17 -0700 (PDT) Received: from localhost (e132581.arm.com [10.1.196.87]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CD5A63F673; Mon, 28 Apr 2025 06:05:23 -0700 (PDT) Date: Mon, 28 Apr 2025 14:05:19 +0100 From: Leo Yan To: Mike Leach Cc: Yabin Cui , Anshuman Khandual , Suzuki K Poulose , James Clark , Jie Gan , Alexander Shishkin , coresight@lists.linaro.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] coresight: trbe: Save/restore state across CPU low power state Message-ID: <20250428130519.GF551819@e132581.arm.com> References: <20250423230046.1134389-1-yabinc@google.com> <731dbb1d-e804-4678-9b8c-40f6395e94a7@arm.com> <20250428122408.GD551819@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-20250428_140534_589923_BC8456EF X-CRM114-Status: GOOD ( 15.92 ) 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 Mon, Apr 28, 2025 at 01:55:29PM +0100, Mike Leach wrote: [...] > > > The TRBE PM can follow the model of the ETE / ETMv4 and save and > > > restore if currently in use. > > > > If TRBE PM is registered as a seperate PM notifier, a prominent issue is > > it cannot promise the depedency between ETE and TRBE when execute CPU > > power management. E.g., when entering CPU idle states, ETE should be > > disabled prior to switch off TRBE, otherwise, it might cause lockup > > issue in hardware. If ETE and TRBE register PM notifier separately, > > we cannot ensure the sequence between ETE and TRBE, this is why we need > > to do the operations based on CoreSight paths. > > > > I believe that the architecture requires that if the disabled TRBE > cannot receive trace then the ETE should regard the trace as having > been output (A1.4 ETE spec). Incorrect sequencing should only result > in missing trace, not a core lockup - unless the implementation is not > compliant. Thanks for clarification, Mike. I would prefer to stick with the CoreSight path approach, as this will help us to resolve the issue in a general way - not just for ETE / TRBE case, this would be applicable for other types of links and sinks. Thanks, Leo