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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 3CA03CA9EBB for ; Thu, 24 Oct 2019 15:38:39 +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 EF7EF20650 for ; Thu, 24 Oct 2019 15:38:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="MvTOAZTG"; dkim=fail reason="key not found in DNS" (0-bit key) header.d=codeaurora.org header.i=@codeaurora.org header.b="DPhM8ugD" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EF7EF20650 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=codeaurora.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 C4B861836; Thu, 24 Oct 2019 15:38:38 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id CE3BE1835 for ; Thu, 24 Oct 2019 15:38:37 +0000 (UTC) Received: from smtp.codeaurora.org (smtp.codeaurora.org [198.145.29.96]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 862648AE for ; Thu, 24 Oct 2019 15:38:37 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 55C9360FB8; Thu, 24 Oct 2019 15:38:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1571931517; bh=I6s631GlwyYFEU5LjYrNUm46MVmmWLmqXsZXm4N9dws=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MvTOAZTGV91JD+mXGz9eEGaJLcPpsYer3uYmmz8uR0ueM27vNW+aZRDgvueA0gNcD kOrH8VUR+16/o8MSEC8o6L/IRZaeoM7GFMJPULd5igZclNLFnIxzeW/W/zRyOAEK8E 1iQ3YTtVTSEJh5yvHxnTCUkyg81QGMhWvpb7YO88= Received: from jcrouse1-lnx.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: jcrouse@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id AC94D60779; Thu, 24 Oct 2019 15:38:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1571931516; bh=I6s631GlwyYFEU5LjYrNUm46MVmmWLmqXsZXm4N9dws=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=DPhM8ugDTSmE4qD0tEvLupFglyf78GFTRbUDo+pv1RC51AY7gwKxeA7HcFQ2zz0Fp re1HTKa1g+zUUIQIqGYBPnOcUeQkx24oeuP0m+Cay4wv4cgvp2MAHjROw1cZTBkGZ/ hsOcV44UWIZWGR1FtcyNtNUVmKfAvyYA2tXl3BSg= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org AC94D60779 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=jcrouse@codeaurora.org Date: Thu, 24 Oct 2019 09:38:33 -0600 From: Jordan Crouse To: Will Deacon Subject: Re: Users of IOMMU_QCOM_SYS_CACHE? Message-ID: <20191024153832.GA7966@jcrouse1-lnx.qualcomm.com> Mail-Followup-To: Will Deacon , iommu@lists.linux-foundation.org, sspatil@android.com, joro@8bytes.org, saiprakash.ranjan@codeaurora.org, robin.murphy@arm.com, smasetty@codeaurora.org References: <20191024105150.GC1242@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20191024105150.GC1242@willie-the-truck> User-Agent: Mutt/1.5.24 (2015-08-30) Cc: smasetty@codeaurora.org, iommu@lists.linux-foundation.org, 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 On Thu, Oct 24, 2019 at 11:51:51AM +0100, Will Deacon wrote: > 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. You are thinking of: https://lore.kernel.org/linux-arm-msm/1538744915-25490-8-git-send-email-smasetty@codeaurora.org/ That is still a thing but it never got revisited after 5.3. I believe that Sharat will have a refresh coming soon. > 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. I wouldn't mind if you plumbed it into the DMA API as well but I would ask to keep an alternate path for those of us who make our own way. Jordan -- The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu