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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_MUTT 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 F0400C43613 for ; Thu, 20 Jun 2019 16:57:28 +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 C363220656 for ; Thu, 20 Jun 2019 16:57:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="DJa/vBXB" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C363220656 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-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=B1tSqahzs/BqQPL/Kepccd1z8lfTovATziPsBgHAlEE=; b=DJa/vBXBuncrhS 9PtCCtCeTXhl2xZ1CpsnGORPKgQfz7moqrL8kqUs9GoA+Mpgf87AOPEr4d+zfYcZfwrNGyflV8Fqu gWC+C5OfxwfElqUM3tXPvSMiMTEuSAnHcBrsPvFpNYzmRzmbwZgitwAdqlQCAHfk8f7I/jVGn97Yd ACczv2El6EwMEXcrJFjCjG5qK6uctMfgNaPSX4ZNAsuchoBueHa3+q4v0Ib7jaLFw/HpgiRsbf1vU byFQWloR7rBliywisjri4qtB6/1CX+Bz2UxlvtrFZuyjBOVgEg1pKk7cgSSLtfBH7pP8CCDkc2ieH uyifyTovIgyN1qS3RYxQ==; 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 1he0NJ-0005NO-AE; Thu, 20 Jun 2019 16:57:25 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1he0NG-0005Mv-Id for linux-arm-kernel@lists.infradead.org; Thu, 20 Jun 2019 16:57:23 +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 B7F3D2B; Thu, 20 Jun 2019 09:57:16 -0700 (PDT) Received: from localhost (unknown [10.37.6.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 388493F246; Thu, 20 Jun 2019 09:57:16 -0700 (PDT) Date: Thu, 20 Jun 2019 17:57:14 +0100 From: Andrew Murray To: Suzuki K Poulose Subject: Re: [PATCH v1 0/5] coresight: etm4x: save/restore ETMv4 context across CPU low power states Message-ID: <20190620165714.GI20984@e119886-lin.cambridge.arm.com> References: <20190618125433.9739-1-andrew.murray@arm.com> <1e4193ca-ebd2-920a-dc88-127ffc279990@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1e4193ca-ebd2-920a-dc88-127ffc279990@arm.com> User-Agent: Mutt/1.10.1+81 (426a6c1) (2018-08-26) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190620_095722_662315_F12764BA X-CRM114-Status: GOOD ( 12.87 ) 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: alexander.shishkin@linux.intel.com, linux-arm-kernel@lists.infradead.org, mathieu.poirier@linaro.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Jun 20, 2019 at 05:45:11PM +0100, Suzuki K Poulose wrote: > > > 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. Yes sure. Thanks, Andrew Murray > > Cheers > Suzuki _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel