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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 32902C43331 for ; Tue, 31 Mar 2020 07:53:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 01DC1207FF for ; Tue, 31 Mar 2020 07:53:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="H3sLQ1Co" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730095AbgCaHxf (ORCPT ); Tue, 31 Mar 2020 03:53:35 -0400 Received: from mail26.static.mailgun.info ([104.130.122.26]:55528 "EHLO mail26.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730030AbgCaHxf (ORCPT ); Tue, 31 Mar 2020 03:53:35 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1585641214; h=Message-ID: References: In-Reply-To: Subject: Cc: To: From: Date: Content-Transfer-Encoding: Content-Type: MIME-Version: Sender; bh=y+g2aIRUiXN9G3r1jVBnLvDDqFYXx0VUiwFi2S/Qu/A=; b=H3sLQ1CoH29ETxKLM+77eHcLhxXLiBvb49NOsnCHYI4QJZ05HDB2aVv318BxGk9l+4k+qCwW CQPSCAGsvcOG5OquZeabsbHAeZqdstu4MEiJG0dX5sZLD2uNIxtXwcQh9vCo6/3OGTUh7Mvz wsHob/VXi0QimV9NbfONeeNdJTs= X-Mailgun-Sending-Ip: 104.130.122.26 X-Mailgun-Sid: WyI1MzIzYiIsICJsaW51eC1hcm0tbXNtQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by mxa.mailgun.org with ESMTP id 5e82f6fe.7f009c56a848-smtp-out-n03; Tue, 31 Mar 2020 07:53:34 -0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1001) id E9797C43637; Tue, 31 Mar 2020 07:53:33 +0000 (UTC) Received: from mail.codeaurora.org (localhost.localdomain [127.0.0.1]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: saiprakash.ranjan) by smtp.codeaurora.org (Postfix) with ESMTPSA id 31674C433F2; Tue, 31 Mar 2020 07:53:33 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Tue, 31 Mar 2020 13:23:33 +0530 From: Sai Prakash Ranjan To: Will Deacon Cc: Doug Anderson , Robin Murphy , Joerg Roedel , "list@263.net:IOMMU DRIVERS , Joerg Roedel ," , linux-arm-msm , LKML Subject: Re: [PATCH] iommu/arm-smmu: Demote error messages to debug in shutdown callback In-Reply-To: <20200331074400.GB25612@willie-the-truck> References: <20200327132852.10352-1-saiprakash.ranjan@codeaurora.org> <0023bc68-45fb-4e80-00c8-01fd0369243f@arm.com> <37db9a4d524aa4d7529ae47a8065c9e0@codeaurora.org> <5858bdac-b7f9-ac26-0c0d-c9653cef841d@arm.com> <890456524e2df548ba5d44752513a62c@codeaurora.org> <20200331074400.GB25612@willie-the-truck> Message-ID: <1bf04938249bcd5b2111c1921facfd25@codeaurora.org> X-Sender: saiprakash.ranjan@codeaurora.org User-Agent: Roundcube Webmail/1.3.9 Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org Hi Will, On 2020-03-31 13:14, Will Deacon wrote: > On Tue, Mar 31, 2020 at 01:06:11PM +0530, Sai Prakash Ranjan wrote: >> On 2020-03-30 23:54, Doug Anderson wrote: >> > On Sat, Mar 28, 2020 at 12:35 AM Sai Prakash Ranjan >> > wrote: >> > > >> > > > Of course the fact that in practice we'll *always* see the warning >> > > > because there's no way to tear down the default DMA domains, and even >> > > > if all devices *have* been nicely quiesced there's no way to tell, is >> > > > certainly less than ideal. Like I say, it's not entirely clear-cut >> > > > either way... >> > > > >> > > >> > > Thanks for these examples, good to know these scenarios in case we >> > > come >> > > across these. >> > > However, if we see these error/warning messages appear everytime then >> > > what will be >> > > the credibility of these messages? We will just ignore these messages >> > > when >> > > these issues you mention actually appears because we see them >> > > everytime >> > > on >> > > reboot or shutdown. >> > >> > I would agree that if these messages are expected to be seen every >> > time, there's no way to fix them, and they're not indicative of any >> > problem then something should be done. Seeing something printed at >> > "dev_error" level with an exclamation point (!) at the end makes me >> > feel like this is something that needs immediate action on my part. >> > >> > If we really can't do better but feel that the messages need to be >> > there, at least make them dev_info and less scary like: >> > >> > arm-smmu 15000000.iommu: turning off; DMA should be quiesced before >> > now >> > >> > ...that would still give you a hint in the logs that if you saw a DMA >> > transaction after the message that it was a bug but also wouldn't >> > sound scary to someone who wasn't seeing any other problems. >> > >> >> We can do this if Robin is OK? > > It would be nice if you could figure out which domains are still live > when > the SMMU is being shut down in your case and verify that it *is* infact > benign before we start making the message more friendly. As Robin said > earlier, rogue DMA is a real nightmare to debug. > I could see this error message for all the clients of apps_smmu. I checked manually enabling bypass and removing iommus dt property for each client of apps_smmu. Thanks, Sai -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation