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=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 D2E68CA9EAF for ; Thu, 24 Oct 2019 10:51:56 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (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 A68F720856 for ; Thu, 24 Oct 2019 10:51:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="BJqk+r6K" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A68F720856 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 7CF841052; Thu, 24 Oct 2019 10:51:56 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id EF8F91050 for ; Thu, 24 Oct 2019 10:51:55 +0000 (UTC) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id B853B8AD for ; Thu, 24 Oct 2019 10:51:55 +0000 (UTC) Received: from willie-the-truck (236.31.169.217.in-addr.arpa [217.169.31.236]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 67B5320679; Thu, 24 Oct 2019 10:51:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1571914315; bh=rzqKwhxIxj2JnBxpVJPeuHaLzYTN6Fj5vVFdfceFnEQ=; h=Date:From:To:Cc:Subject:From; b=BJqk+r6Kx/7BR9WdSP7CN6krfoq2sS8XypeO/0d19RNgbmVIu8AzUoBdPZq5vpKLu gnK7XeCB5R4RKfICIQGKuR+mbQRAl/3VOfoVLXwxXrLMvaFAWE6KW+OIZwe2sjvGH5 fUaJZwxgKGe+5+HWckMB+70bDbWPLqCYQMbWAtYQ= Date: Thu, 24 Oct 2019 11:51:51 +0100 From: Will Deacon To: iommu@lists.linux-foundation.org Subject: Users of IOMMU_QCOM_SYS_CACHE? Message-ID: <20191024105150.GC1242@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) Cc: robin.murphy@arm.com, sspatil@android.com X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 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 Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org Hi all, In commit 90ec7a76cc4b ("iommu/io-pgtable-arm: Add support to use system cache") we added support for IOMMU_QCOM_SYS_CACHE which was merged into 5.3. This allows non-coherent devices to request an outer cacheable memory type.... except that nobody actually does this in mainline. I remember there being a potential DRM user but I don't know what happened to it. Given that this isn't actually exposed in the DMA API, I worry that we're just carrying part of an out-of-tree hack here and propose that we drop the flag altogether unless we get an upstream user, preferably by plumbing this into the DMA API via a new attribute. Thoughts? Will _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu