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=-6.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 E22E5C07E96 for ; Tue, 6 Jul 2021 13:31:42 +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 A1D0461975 for ; Tue, 6 Jul 2021 13:31:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A1D0461975 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+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.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:Cc:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=e2uV6dEH6aFhf/m/+h3Ap636WkBNB+dJtL7VR1MudnA=; b=JHTq7/oFNlTJ5THeGg1AIceyVB 1cptnxCg5z9zIjLtc4d92a4urZCzkza6iVTXZskSKylY7NHwspULJ06TY94YDt652XeEKPXgmMXEx YeDvZm/xCv3IBecTNYRpsmp0BW+6KDzc7Oj8upfIB4+fGSYjyAcRgSFNCCRbCK6xmKscYjC/5ww8P 2lcGcztv7UksclTH6quHxm0LLUH9XrSgm86jYm7OVJkYUUFx+aJ9T2zDRk5umheE4Wk7PlpzXmu53 sq0jH88hI3MgNL1DpDDIoGlFIXS/OaNTYs38xfI6hgH9925DkMT++JXupf51noc24Gxl7ybjf9FCb eS+17hFQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m0l8o-00Bt7a-Qz; Tue, 06 Jul 2021 13:29:34 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1m0l8f-00Bt7D-N4 for linux-arm-kernel@lists.infradead.org; Tue, 06 Jul 2021 13:29:27 +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 667CC1FB; Tue, 6 Jul 2021 06:29:18 -0700 (PDT) Received: from [10.57.40.45] (unknown [10.57.40.45]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B294E3F73B; Tue, 6 Jul 2021 06:29:16 -0700 (PDT) Subject: Re: [PATCH] arm64: cache: Lower ARCH_DMA_MINALIGN to 64 (L1_CACHE_BYTES) To: Catalin Marinas , Yassine Oudjana Cc: "will@kernel.org" , "ardb@kernel.org" , "arnd@arndb.de" , "kernel-team@android.com" , "linux-arm-kernel@lists.infradead.org" , "mark.rutland@arm.com" , "vincent.whitchurch@axis.com" , "linux-arm-msm@vger.kernel.org" References: <20210527124356.22367-1-will@kernel.org> <20210706102634.GB24903@arm.com> From: Robin Murphy Message-ID: <59800d6c-364a-f4be-e341-c5b531657ba3@arm.com> Date: Tue, 6 Jul 2021 14:29:07 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210706102634.GB24903@arm.com> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210706_062925_858886_98F826A7 X-CRM114-Status: GOOD ( 16.79 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2021-07-06 11:26, Catalin Marinas wrote: > On Tue, Jul 06, 2021 at 09:26:59AM +0000, Yassine Oudjana wrote: >> In-Reply-To: <20210527124356.22367-1-will@kernel.org> >>> Reduce ARCH_DMA_MINALIGN to 64 bytes and allow the warning/taint to >>> indicate if there are machines that unknowingly rely on this. >> >> The warning is being triggered on Qualcomm MSM8996, as well as the out-of-spec taint: > > Is this booting with ACPI or DT? > >> ------------[ cut here ]------------ >> rtc-pm8xxx 400f000.qcom,spmi:pmic@0:rtc@6000: ARCH_DMA_MINALIGN smaller than CTR_EL0.CWG (64 < 128) >> WARNING: CPU: 0 PID: 1 at arch/arm64/mm/dma-mapping.c:45 arch_setup_dma_ops+0xf8/0x10c > [...] >> This warning is triggered with nearly every driver probe, not only rtc-pm8xxx. > > I have a suspicion none of the reported devices actually do any DMA, so > in practice it should be safe but we need to figure out why > arch_setup_dma_ops() gets called. It gets called because there's no straightforward way to know that a platform device *isn't* DMA-capable, so we have to assume they are. I would also assume that in a Qcom SoC there really are at least some things doing non-coherent DMA :( Robin. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel