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=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 9415CCA9EA0 for ; Mon, 28 Oct 2019 07:42:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F33A214E0 for ; Mon, 28 Oct 2019 07:42:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733026AbfJ1Hl7 (ORCPT ); Mon, 28 Oct 2019 03:41:59 -0400 Received: from verein.lst.de ([213.95.11.211]:33125 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730952AbfJ1Hl7 (ORCPT ); Mon, 28 Oct 2019 03:41:59 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 5AF8668C65; Mon, 28 Oct 2019 08:41:56 +0100 (CET) Date: Mon, 28 Oct 2019 08:41:56 +0100 From: Christoph Hellwig To: isaacm@codeaurora.org Cc: Christoph Hellwig , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, joro@8bytes.org, m.szyprowski@samsung.com, robin.murphy@arm.com, will@kernel.org, pratikp@codeaurora.org, lmark@codeaurora.org Subject: Re: [PATCH] iommu/dma: Add support for DMA_ATTR_SYS_CACHE Message-ID: <20191028074156.GB20443@lst.de> References: <1572050616-6143-1-git-send-email-isaacm@codeaurora.org> <20191026053026.GA14545@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 26, 2019 at 03:12:57AM -0700, isaacm@codeaurora.org wrote: > On 2019-10-25 22:30, Christoph Hellwig wrote: >> The definition makes very little sense. > Can you please clarify what part doesn’t make sense, and why? It looks like complete garbage to me. That might just be because it uses tons of terms I've never heard of of and which aren't used anywhere in the DMA API. It also might be because it doesn't explain how the flag might actually be practically useful. > This is > really just an extension of this patch that got mainlined, so that clients > that use the DMA API can use IOMMU_QCOM_SYS_CACHE as well: > https://patchwork.kernel.org/patch/10946099/ >> Any without a user in the same series it is a complete no-go anyway. > IOMMU_QCOM_SYS_CACHE does not have any current users in the mainline, nor > did it have it in the patch series in which it got merged, yet it is still > present? Furthermore, there are plans to upstream support for one of our > SoCs that may benefit from this, as seen here: > https://www.spinics.net/lists/iommu/msg39608.html. Which means it should have never been merged. As a general policy we do not add code to the Linux kernel without actual users. 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=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 72D13CA9EA0 for ; Mon, 28 Oct 2019 07:42:02 +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 4494D21783 for ; Mon, 28 Oct 2019 07:42:02 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4494D21783 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 mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id F2CB4B1F; Mon, 28 Oct 2019 07:42:01 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 5248AB0B for ; Mon, 28 Oct 2019 07:42:00 +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 smtp1.linuxfoundation.org (Postfix) with ESMTPS id C5C9142D for ; Mon, 28 Oct 2019 07:41:59 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 5AF8668C65; Mon, 28 Oct 2019 08:41:56 +0100 (CET) Date: Mon, 28 Oct 2019 08:41:56 +0100 From: Christoph Hellwig To: isaacm@codeaurora.org Subject: Re: [PATCH] iommu/dma: Add support for DMA_ATTR_SYS_CACHE Message-ID: <20191028074156.GB20443@lst.de> References: <1572050616-6143-1-git-send-email-isaacm@codeaurora.org> <20191026053026.GA14545@lst.de> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Cc: will@kernel.org, linux-kernel@vger.kernel.org, pratikp@codeaurora.org, iommu@lists.linux-foundation.org, lmark@codeaurora.org, robin.murphy@arm.com, Christoph Hellwig 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="utf-8" Content-Transfer-Encoding: base64 Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org T24gU2F0LCBPY3QgMjYsIDIwMTkgYXQgMDM6MTI6NTdBTSAtMDcwMCwgaXNhYWNtQGNvZGVhdXJv cmEub3JnIHdyb3RlOgo+IE9uIDIwMTktMTAtMjUgMjI6MzAsIENocmlzdG9waCBIZWxsd2lnIHdy b3RlOgo+PiBUaGUgZGVmaW5pdGlvbiBtYWtlcyB2ZXJ5IGxpdHRsZSBzZW5zZS4KPiBDYW4geW91 IHBsZWFzZSBjbGFyaWZ5IHdoYXQgcGFydCBkb2VzbuKAmXQgbWFrZSBzZW5zZSwgYW5kIHdoeT8K Ckl0IGxvb2tzIGxpa2UgY29tcGxldGUgZ2FyYmFnZSB0byBtZS4gIFRoYXQgbWlnaHQganVzdCBi ZSBiZWNhdXNlIGl0CnVzZXMgdG9ucyBvZiB0ZXJtcyBJJ3ZlIG5ldmVyIGhlYXJkIG9mIG9mIGFu ZCB3aGljaCBhcmVuJ3QgdXNlZCBhbnl3aGVyZQppbiB0aGUgRE1BIEFQSS4gIEl0IGFsc28gbWln aHQgYmUgYmVjYXVzZSBpdCBkb2Vzbid0IGV4cGxhaW4gaG93IHRoZQpmbGFnIG1pZ2h0IGFjdHVh bGx5IGJlIHByYWN0aWNhbGx5IHVzZWZ1bC4KCj4gVGhpcyBpcyAKPiByZWFsbHkganVzdCBhbiBl eHRlbnNpb24gb2YgdGhpcyBwYXRjaCB0aGF0IGdvdCBtYWlubGluZWQsIHNvIHRoYXQgY2xpZW50 cyAKPiB0aGF0IHVzZSB0aGUgRE1BIEFQSSBjYW4gdXNlIElPTU1VX1FDT01fU1lTX0NBQ0hFIGFz IHdlbGw6IAo+IGh0dHBzOi8vcGF0Y2h3b3JrLmtlcm5lbC5vcmcvcGF0Y2gvMTA5NDYwOTkvCj4+ ICBBbnkgd2l0aG91dCBhIHVzZXIgaW4gdGhlIHNhbWUgc2VyaWVzIGl0IGlzIGEgY29tcGxldGUg bm8tZ28gYW55d2F5Lgo+IElPTU1VX1FDT01fU1lTX0NBQ0hFIGRvZXMgbm90IGhhdmUgYW55IGN1 cnJlbnQgdXNlcnMgaW4gdGhlIG1haW5saW5lLCBub3IgCj4gZGlkIGl0IGhhdmUgaXQgaW4gdGhl IHBhdGNoIHNlcmllcyBpbiB3aGljaCBpdCBnb3QgbWVyZ2VkLCB5ZXQgaXQgaXMgc3RpbGwgCj4g cHJlc2VudD8gRnVydGhlcm1vcmUsIHRoZXJlIGFyZSBwbGFucyB0byB1cHN0cmVhbSBzdXBwb3J0 IGZvciBvbmUgb2Ygb3VyIAo+IFNvQ3MgdGhhdCBtYXkgYmVuZWZpdCBmcm9tIHRoaXMsIGFzIHNl ZW4gaGVyZTogCj4gaHR0cHM6Ly93d3cuc3Bpbmljcy5uZXQvbGlzdHMvaW9tbXUvbXNnMzk2MDgu aHRtbC4KCldoaWNoIG1lYW5zIGl0IHNob3VsZCBoYXZlIG5ldmVyIGJlZW4gbWVyZ2VkLiAgQXMg YSBnZW5lcmFsIHBvbGljeSB3ZSBkbwpub3QgYWRkIGNvZGUgdG8gdGhlIExpbnV4IGtlcm5lbCB3 aXRob3V0IGFjdHVhbCB1c2Vycy4KX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX18KaW9tbXUgbWFpbGluZyBsaXN0CmlvbW11QGxpc3RzLmxpbnV4LWZvdW5kYXRp b24ub3JnCmh0dHBzOi8vbGlzdHMubGludXhmb3VuZGF0aW9uLm9yZy9tYWlsbWFuL2xpc3RpbmZv L2lvbW11