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=-2.2 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 3600FC433FF for ; Sat, 3 Aug 2019 10:30:32 +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 0AA182166E for ; Sat, 3 Aug 2019 10:30:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="f5tiOR/Z" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0AA182166E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de 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=jrtxYykTOwSnVxSoRWOghLivx2rjUzz/U4eMI1c6uJo=; b=f5tiOR/ZtXKBIy rRr2NXWuuDXY0QRfgvqVkxiacNkCuhTNYdtFIDWdF0sjdvimIzLtkLMI/xIV0uG6SPCyx25TlwSK+ x9VVySDQLM3gYx4GjKFqx++2x999+gbWmYh7Oegi/PZRhwFf7oqOjuIzzskvvurF5Qxai9opMtSUP 3vYWpHscYII7UILNklIX7yLWMmYULwHxZqhbgB6/BHXU4SdMBs/OT4NTB7BaD6N+A6EzD8Af6Evyh CaOBd467+Ugy591XNtJwC+q19n/pczQ+XVafGFO5gGdra2h46gsvAm/mdVcdmH8IpbTtRmr3NjYK7 lWm/h9Z4TSvYsFr26RZQ==; 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 1htrJ1-0002Gp-Hz; Sat, 03 Aug 2019 10:30:31 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1htrIz-0002GW-7o for linux-arm-kernel@lists.infradead.org; Sat, 03 Aug 2019 10:30:30 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 4321A227A81; Sat, 3 Aug 2019 12:30:24 +0200 (CEST) Date: Sat, 3 Aug 2019 12:30:24 +0200 From: Christoph Hellwig To: Takashi Iwai Subject: Re: [PATCH 5/5] dma-mapping: remove ARCH_NO_COHERENT_DMA_MMAP Message-ID: <20190803103024.GA32624@lst.de> References: <20190725063401.29904-1-hch@lst.de> <20190725063401.29904-6-hch@lst.de> <20190802070354.GA8280@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190803_033029_427960_B934BD20 X-CRM114-Status: GOOD ( 12.70 ) 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: linux-xtensa@linux-xtensa.org, Michal Simek , linux-parisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-m68k@lists.linux-m68k.org, Robin Murphy , x86@kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, linuxppc-dev@lists.ozlabs.org, Christoph Hellwig , linux-arm-kernel@lists.infradead.org, Marek Szyprowski 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 Fri, Aug 02, 2019 at 10:24:02AM +0200, Takashi Iwai wrote: > I wasn't careful enough to look at that change, sorry. > > The code there tries to check whether dma_mmap_coherent() would always > fail on some platforms. Then the driver clears the mmap capability > flag at the device open time and notifies user-space to fall back to > the dumb read/write mode. > > So I'm afraid that simply dropping the check would cause the behavior > regression, e.g. on PARISC. > > Is there any simple way to test whether dma_mmap_coherent() would work > or not in general on the target platform? It's not necessarily in an > ifdef at all. This isn't really a platform, but a per-device question. I can add a "bool dma_can_mmap(struct device *dev)" helper to check that. But how do I get at a suitable struct device in hw_support_mmap()? _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel