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=-2.5 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,USER_AGENT_SANE_1 autolearn=no 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 E7D19C06516 for ; Thu, 4 Jul 2019 10:21:32 +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 C0ECB218A0 for ; Thu, 4 Jul 2019 10:21:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Z6Rg2aKQ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C0ECB218A0 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=VCMCzOQdcGv7Ai2YkM1y0sKvEy71g4zQcjUGxzE0Tu0=; b=Z6Rg2aKQbO4vxe M+L2wSQNijBJe1eln+DLQA8goLlLByAYoj0TGDM8bYbJEhLAZbbKBINBMPUYZu9/kLeRoxcRkXnQH gnyILnz4XmQpW32H6jbvrg8xMy/4yKN0oQzApDr8w9Pu/oUfv11BaCEARJnElKgXFGJUeTiWQhHQG jMUyOXvf8Jz/so/hf0fZcy2R+xNEoyCbkaPGicebaBwLmm8NzcMahgRuFFlbuSijeiO4OpppYVZdM 54yXntvRWrbOos5dujXtHOQUYvbRTQAOmSHLCsB23CVSMPkA+PFMqBGV+Ffnr977AniDE5+ysvRAi /Dp4S75L0L4Qg97ovPfA==; 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 1hiyrm-0002C3-KT; Thu, 04 Jul 2019 10:21:26 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hiyrj-0002Bi-Jh for linux-arm-kernel@lists.infradead.org; Thu, 04 Jul 2019 10:21:24 +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 D9EF4344; Thu, 4 Jul 2019 03:21:22 -0700 (PDT) Received: from localhost (unknown [10.37.6.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 59B313F703; Thu, 4 Jul 2019 03:21:22 -0700 (PDT) Date: Thu, 4 Jul 2019 11:21:20 +0100 From: Andrew Murray To: Leo Yan Subject: Re: [PATCH v2 5/5] coresight: etm4x: save/restore state across CPU low power states Message-ID: <20190704102120.GE7227@e119886-lin.cambridge.arm.com> References: <20190627083525.37463-6-andrew.murray@arm.com> <20190628080732.GA32370@leoy-ThinkPad-X240s> <20190628085357.GH34530@e119886-lin.cambridge.arm.com> <20190628091246.GE32370@leoy-ThinkPad-X240s> <20190628092227.GJ34530@e119886-lin.cambridge.arm.com> <20190701020710.GC28475@leoy-ThinkPad-X240s> <20190701093458.GA27745@e119886-lin.cambridge.arm.com> <20190701094811.GB32042@leoy-ThinkPad-X240s> <20190701095444.GB27745@e119886-lin.cambridge.arm.com> <20190701101440.GD32042@leoy-ThinkPad-X240s> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190701101440.GD32042@leoy-ThinkPad-X240s> 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-20190704_032123_695653_AAE342DE X-CRM114-Status: GOOD ( 19.66 ) 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: Mathieu Poirier , Suzuki K Poulose , Alexander Shishkin , coresight@lists.linaro.org, Sudeep Holla , linux-arm-kernel@lists.infradead.org, Mike Leach 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 Mon, Jul 01, 2019 at 06:14:40PM +0800, Leo Yan wrote: > On Mon, Jul 01, 2019 at 10:54:44AM +0100, Andrew Murray wrote: > > On Mon, Jul 01, 2019 at 05:48:11PM +0800, Leo Yan wrote: > > > On Mon, Jul 01, 2019 at 10:34:58AM +0100, Andrew Murray wrote: > > > > > > [...] > > > > > > > > > In any case, not only do we want to override the firmware to always > > > > > > save/restore. Sometimes we may also want to override the firmware to never > > > > > > save/restore (despite the firmware having the > > > > > > 'arm,coresight-needs-save-restore' flag present). For example to debug power > > > > > > management. > > > > > > > > > > > > Thus with this current approach you can override the firmware to either enable > > > > > > or disable save/restore. > > > > > > > > > > Thanks for explanation and agree with this. Just a suggestion, maybe we > > > > > can initialize 'drvdata->pm_save_enable' in probe as below: > > > > > > > > > > if (pm_save_enable == PARAM_PM_SAVE_FIRMWARE) > > > > > drvdata->pm_save_enable = etm4_needs_save_restore(dev); > > > > > else > > > > > drvdata->pm_save_enable = pm_save_enable; > > > > > > > > > > From then on, we can only use 'drvdata->pm_save_enable' and don't need > > > > > to check the module parameter anymore. > > > > > > > > This is OK, however it means you can't then change the mode once the driver > > > > is probed. I.e. you can't echo values into > > > > /sys/module/coresight-etm4x/pm_save_enable at runtime. This was useful to > > > > me during testing, I assumed it may be useful for others too (especially > > > > given that you can't unload the module). > > > > > > Ah, okay, this is fine for me. Thanks for sharing the knowledge. > > > > Thanks for the review, can I add your Reviewed-By? > > Yes, please. Usually, I would like to give a test for patches, this > patch is important for productions after enable CoreSight with CPU > idle; but some platforms are easily to hang after enable CPU idle with > Coresight. > > So if you suggest to test this patch set on some public platform, I > can give a testing on it (if I have the boards). I've only been able to test this on a Juno (which doesn't suffer from this issue). Perhaps Mathieu can suggest known platforms that require cpuidle disabled to use coresight? Thanks, Andrew Murray > > Thanks, > Leo Yan _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel