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,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 16B5DC0650E for ; Mon, 1 Jul 2019 09:54:53 +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 DD87520881 for ; Mon, 1 Jul 2019 09:54:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Psfbx1EM" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org DD87520881 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=Ao6DU2oFaNA8YLP2DEKkEwqx44QulmzellJ0tGhNlkY=; b=Psfbx1EMi2afW2 vPQBOSzyNlNgeRLNFEkQr7yEpGmb0xWFO7Rk34UrEr9O4CPhRR9Sl5msUkymro1AsmVAr3u8LNGoo 6gmEcqnQasVEvJ06NWyxcGayIcyywenqkbWUeQjPbbONPOpaT54BTuRBRLq/LaUG0z9RDgXvO6ajt Vs3X0NMtmBD0u2KvJoT+Roc8hPVQ3T/4GNKxmva7lMr412C+aHmslE+DDRQ0p38nn8twveOwoW+CI oJNil1FQZGti4TDenhtNOnTn8rV4Yxqk8jQP+FfX6GR8g1B/ToeP9gqNMFGxMvULGoPzwUKjbFiE3 WzRzUNjaLnnZA8aBNUXg==; 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 1hht1O-0008Pv-Hb; Mon, 01 Jul 2019 09:54:50 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hht1L-0008Pb-CD for linux-arm-kernel@lists.infradead.org; Mon, 01 Jul 2019 09:54:48 +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 952D32B; Mon, 1 Jul 2019 02:54:46 -0700 (PDT) Received: from localhost (unknown [10.37.6.20]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 168153F718; Mon, 1 Jul 2019 02:54:45 -0700 (PDT) Date: Mon, 1 Jul 2019 10:54:44 +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: <20190701095444.GB27745@e119886-lin.cambridge.arm.com> References: <20190627083525.37463-1-andrew.murray@arm.com> <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> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190701094811.GB32042@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-20190701_025447_464828_6AB640E2 X-CRM114-Status: GOOD ( 15.74 ) 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 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? 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