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,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 0B7CDC83000 for ; Tue, 28 Apr 2020 13:06:32 +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 D2352206D9 for ; Tue, 28 Apr 2020 13:06:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Ybj/7O9h" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D2352206D9 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-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=THx+ekVMNXGX98YVoMO1nxAUvS86LkXcr1WwaxFrNdc=; b=Ybj/7O9hlHIfqrb6hCQ+zXDvh ONXJUB1zAhGRMtt8ZQz9dB05V5L44sAqAjuz7syFlAxd+39Vb9kcW136DPqtVJXMHuVpuhdIQUD53 cHxiAlzt9GV/k7w9npRjKkwWaXwQMgrVUJwe17N2nvUN0IXz7c1QHSNU6D+kio6Weh3Uu+NXpf/x7 jjiSNBx9UsKILejDP0DEomM1bV9Sjx1M+MUtACxXefmjsa6ePvglvhsZsCZQqUDhdzC8K4XScDJVY zBj8rlANj7MtzwJAkRA0J5iLGTOTjpadqS1Yf20k8SxO+ACNnB4Z7tLtkaNA0WMNOrNT0O6Ipq0wn JPa/j3iSg==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jTPwS-000861-98; Tue, 28 Apr 2020 13:06:28 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jTPwP-00085T-Sy for linux-arm-kernel@lists.infradead.org; Tue, 28 Apr 2020 13:06:27 +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 145BA31B; Tue, 28 Apr 2020 06:06:25 -0700 (PDT) Received: from [10.57.33.170] (unknown [10.57.33.170]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 710363F68F; Tue, 28 Apr 2020 06:06:21 -0700 (PDT) Subject: Re: [PATCH v3 02/16] mfd: mfd-core: Don't overwrite the dma_mask of the child device To: Andy Shevchenko , Michael Walle References: <20200423174543.17161-1-michael@walle.cc> <20200423174543.17161-3-michael@walle.cc> <20200428124548.GS185537@smile.fi.intel.com> From: Robin Murphy Message-ID: <3cd3705a-4f48-6a46-e869-3ee11dc17323@arm.com> Date: Tue, 28 Apr 2020 14:06:20 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200428124548.GS185537@smile.fi.intel.com> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200428_060625_991455_24406727 X-CRM114-Status: GOOD ( 15.81 ) 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: devicetree@vger.kernel.org, Linus Walleij , Thierry Reding , Lee Jones , Jason Cooper , Marc Zyngier , Bartosz Golaszewski , =?UTF-8?Q?Uwe_Kleine-K=c3=b6nig?= , Guenter Roeck , linux-pwm@vger.kernel.org, Jean Delvare , linux-watchdog@vger.kernel.org, linux-gpio@vger.kernel.org, Mark Brown , Thomas Gleixner , Wim Van Sebroeck , linux-arm-kernel@lists.infradead.org, linux-hwmon@vger.kernel.org, Greg Kroah-Hartman , linux-kernel@vger.kernel.org, Li Yang , Rob Herring , Shawn Guo Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-04-28 1:45 pm, Andy Shevchenko wrote: > On Thu, Apr 23, 2020 at 07:45:29PM +0200, Michael Walle wrote: >> Commit cdfee5623290 ("driver core: initialize a default DMA mask for >> platform device") initialize the DMA of a platform device. But if the >> parent doesn't have a dma_mask set, for example if it's an I2C device, >> the dma_mask of the child platform device will be set to zero again. >> Which leads to many "DMA mask not set" warnings, if the MFD cell has the >> of_compatible property set. > > I'm wondering why parent doesn't have it. Because the parent isn't on a DMA-capable bus, and thus really shouldn't have a valid DMA configuration ever. > I remember we have explicit patches in the past for buses such as PCI and AMBA > to set default DMA mask for all physical devices on the respective bus, of > course they can individually override it later. > > So, this seems to me a paper over the real issue (absence of default DMA mask > where it's needed) and devices should explicitly define it if they disagree > with default. > > If I'm wrong, you really need elaborate commit message much better. The problem here is that MFD children are created as platform devices (regardless of what their parent is) and assigned an of_node, at which point they look pretty much indistinguishable from SoC devices created by the of_platform code, that *do* have to be assumed to be DMA-capable to prevent ~90% of existing devicetrees from breaking. Of course the real fundamental issue is the platform bus itself, but it's way too late to fix that :( Robin. _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel