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=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 84452C35657 for ; Fri, 21 Feb 2020 14:17:10 +0000 (UTC) Received: from silver.osuosl.org (smtp3.osuosl.org [140.211.166.136]) (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 55132222C4 for ; Fri, 21 Feb 2020 14:17:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 55132222C4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by silver.osuosl.org (Postfix) with ESMTP id 206852206E; Fri, 21 Feb 2020 14:17:10 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from silver.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 1UHYjav09G-c; Fri, 21 Feb 2020 14:17:07 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by silver.osuosl.org (Postfix) with ESMTP id 93B7F220C2; Fri, 21 Feb 2020 14:17:05 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 79DCCC07FE; Fri, 21 Feb 2020 14:17:05 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 91FA2C013E for ; Fri, 21 Feb 2020 14:17:03 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 7ABBF86FEF for ; Fri, 21 Feb 2020 14:17:03 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 4h2hTH2P2+Lx for ; Fri, 21 Feb 2020 14:17:02 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by whitealder.osuosl.org (Postfix) with ESMTPS id 0C3CF868E7 for ; Fri, 21 Feb 2020 14:17:02 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 36BC968BFE; Fri, 21 Feb 2020 15:16:57 +0100 (CET) Date: Fri, 21 Feb 2020 15:16:56 +0100 From: Christoph Hellwig To: Robin Murphy Subject: Re: [PATCH 1/2] dma-mapping: support setting memory uncached in place Message-ID: <20200221141656.GF6968@lst.de> References: <20200220170139.387354-1-hch@lst.de> <20200220170139.387354-2-hch@lst.de> <502fa745-ddad-f91b-52bc-52edecf8fdbc@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <502fa745-ddad-f91b-52bc-52edecf8fdbc@arm.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: Jonas Bonn , Mark Rutland , linux-kernel@vger.kernel.org, Stefan Kristiansson , iommu@lists.linux-foundation.org, openrisc@lists.librecores.org, linux-arch@vger.kernel.org, Stafford Horne , Will Deacon , Christoph Hellwig , linux-arm-kernel@lists.infradead.org X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Thu, Feb 20, 2020 at 05:21:35PM +0000, Robin Murphy wrote: >> @@ -196,10 +192,15 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, >> memset(ret, 0, size); >> - if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT) && >> - dma_alloc_need_uncached(dev, attrs)) { >> + if (dma_alloc_need_uncached(dev, attrs)) { >> arch_dma_prep_coherent(page, size); >> - ret = uncached_kernel_address(ret); >> + >> + if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED)) { >> + if (!arch_dma_set_uncached(ret, size)) >> + goto out_free_pages; >> + } else if (IS_ENABLED(CONFIG_ARCH_HAS_UNCACHED_SEGMENT)) { >> + ret = uncached_kernel_address(ret); > > Hmm, would we actually need to keep ARCH_HAS_UNCACHED_SEGMENT? If > arch_dma_set_uncached() returned void*/ERR_PTR instead, then it could work > for both cases (with arch_dma_clear_uncached() being a no-op for segments). Yes, I think so. I was a little worried about what to do with cached_kernel_address() in that scheme, but it turns out with the recent round of dma-direct cleanup that is actually entirely unused now. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu