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 X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E386CC43613 for ; Thu, 20 Jun 2019 16:45:31 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id B1A442084E for ; Thu, 20 Jun 2019 16:45:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="WqYFMeN7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B1A442084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=wfE/BGVI7p3s9KUj4VDM7nLe/sIpQTAAyk7gGe7qvyw=; b=WqYFMeN7Uwr5ny7b8hsmNMpKS 7ORtUzJty6oTRinXQjGtrJOWQ8XDtttJNgtFzRbtq7kfewpWo0whmS09D1w27BqvFPGe4mxBVirSk Eh71WLoLqV2Y5KIdW4Zw938vi/Msfxwkuv86PzwWAS5DJt7uYjFPxjk/zZdHqIxWSwUFz6p0ZtBrJ VKManNNm91Sd9WQGM2eczDoE7+GwXl2Hpwvq1ToObl61rAFFvjqlceRlm3zp5N1KjVeiNjnpFHI+W ScTmyynqJmPwooBnpGooVwXj6eqV7nI+vGEsXlfaaYYuMk3CqVGncst8YESR0a8GD93f39yw9NCDB 3Uapfp9dg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1he0Bb-0008B8-6W; Thu, 20 Jun 2019 16:45:19 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1he0BX-0008Ah-6H for linux-arm-kernel@lists.infradead.org; Thu, 20 Jun 2019 16:45:16 +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 88B9BCFC; Thu, 20 Jun 2019 09:45:13 -0700 (PDT) Received: from [10.1.196.93] (en101.cambridge.arm.com [10.1.196.93]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id F1EA13F246; Thu, 20 Jun 2019 09:45:12 -0700 (PDT) Subject: Re: [PATCH v1 0/5] coresight: etm4x: save/restore ETMv4 context across CPU low power states To: andrew.murray@arm.com, mathieu.poirier@linaro.org, alexander.shishkin@linux.intel.com References: <20190618125433.9739-1-andrew.murray@arm.com> From: Suzuki K Poulose Message-ID: <1e4193ca-ebd2-920a-dc88-127ffc279990@arm.com> Date: Thu, 20 Jun 2019 17:45:11 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190618125433.9739-1-andrew.murray@arm.com> Content-Language: en-US X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190620_094515_284783_2B97D0D2 X-CRM114-Status: GOOD ( 13.64 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 18/06/2019 13:54, Andrew Murray wrote: > Some hardware will ignore bit TRCPDCR.PU which is used to signal > to hardware that power should not be removed from the trace unit. > Let's mitigate against this by saving and restoring the trace > unit state when the CPU enters low power states. > > To provide a benefit to both self-hosted and external debuggers > we save/restore the entire state which includes etmv4_config data > and dynamic data such as inflight counter values, sequencer > states, etc. Andrew, Please could you also mention that there is a kernel command line parameter to control the save/restore here and in the patch which introduces it ? I think this missing information is creating the confusion. Cheers Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel