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,UNPARSEABLE_RELAY,USER_AGENT_SANE_2 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 CE74FC433FF for ; Thu, 15 Aug 2019 10:18:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AB54B208C2 for ; Thu, 15 Aug 2019 10:18:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730947AbfHOKSx (ORCPT ); Thu, 15 Aug 2019 06:18:53 -0400 Received: from mailgw02.mediatek.com ([1.203.163.81]:16840 "EHLO mailgw02.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1729838AbfHOKSx (ORCPT ); Thu, 15 Aug 2019 06:18:53 -0400 X-UUID: 320ceda1c3274245bf1a01ca9a4c4a64-20190815 X-UUID: 320ceda1c3274245bf1a01ca9a4c4a64-20190815 Received: from mtkcas36.mediatek.inc [(172.27.4.253)] by mailgw02.mediatek.com (envelope-from ) (mailgw01.mediatek.com ESMTP with TLS) with ESMTP id 1914054432; Thu, 15 Aug 2019 18:18:47 +0800 Received: from MTKCAS36.mediatek.inc (172.27.4.186) by MTKMBS31N2.mediatek.inc (172.27.4.87) with Microsoft SMTP Server (TLS) id 15.0.1395.4; Thu, 15 Aug 2019 18:18:39 +0800 Received: from [10.17.3.153] (172.27.4.253) by MTKCAS36.mediatek.inc (172.27.4.170) with Microsoft SMTP Server id 15.0.1395.4 via Frontend Transport; Thu, 15 Aug 2019 18:18:42 +0800 Message-ID: <1565864318.14278.4.camel@mhfsdcap03> Subject: Re: [PATCH v9 08/21] iommu/io-pgtable-arm-v7s: Extend MediaTek 4GB Mode From: Yong Wu To: Will Deacon CC: Joerg Roedel , Matthias Brugger , Robin Murphy , Rob Herring , Evan Green , Tomasz Figa , , , , , , , , Nicolas Boichat , , Matthias Kaehlcke , , , Date: Thu, 15 Aug 2019 18:18:38 +0800 In-Reply-To: <20190815095123.rzgtpklvhtjlqir4@willie-the-truck> References: <1565423901-17008-1-git-send-email-yong.wu@mediatek.com> <1565423901-17008-9-git-send-email-yong.wu@mediatek.com> <20190814144059.ruyc45yoqkwpbuga@willie-the-truck> <1565858869.12818.51.camel@mhfsdcap03> <20190815095123.rzgtpklvhtjlqir4@willie-the-truck> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.10.4-0ubuntu2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-SNTS-SMTP: E025A19421E7A1D3E1417135ABBC09AAB1F444894762B73446C1A1D4F4AC54C82000:8 X-MTK: N Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2019-08-15 at 10:51 +0100, Will Deacon wrote: > On Thu, Aug 15, 2019 at 04:47:49PM +0800, Yong Wu wrote: > > On Wed, 2019-08-14 at 15:41 +0100, Will Deacon wrote: > > > On Sat, Aug 10, 2019 at 03:58:08PM +0800, Yong Wu wrote: > > > > MediaTek extend the arm v7s descriptor to support the dram over 4GB. > > > > > > > > In the mt2712 and mt8173, it's called "4GB mode", the physical address > > > > is from 0x4000_0000 to 0x1_3fff_ffff, but from EMI point of view, it > > > > is remapped to high address from 0x1_0000_0000 to 0x1_ffff_ffff, the > > > > bit32 is always enabled. thus, in the M4U, we always enable the bit9 > > > > for all PTEs which means to enable bit32 of physical address. Here is > > > > the detailed remap relationship in the "4GB mode": > > > > CPU PA -> HW PA > > > > 0x4000_0000 0x1_4000_0000 (Add bit32) > > > > 0x8000_0000 0x1_8000_0000 ... > > > > 0xc000_0000 0x1_c000_0000 ... > > > > 0x1_0000_0000 0x1_0000_0000 (No change) > > > > > > So in this example, there are no PAs below 0x4000_0000 yet you later > > > add code to deal with that: > > > > > > > + /* Workaround for MTK 4GB Mode: Add BIT32 only when PA < 0x4000_0000.*/ > > > > + if (cfg->oas == ARM_V7S_MTK_4GB_OAS && paddr < 0x40000000UL) > > > > + paddr |= BIT_ULL(32); > > > > > > Why? Mainline currently doesn't do anything like this for the "4gb mode" > > > support as far as I can tell. In fact, we currently unconditionally set > > > bit 32 in the physical address returned by iova_to_phys() which wouldn't > > > match your CPU PAs listed above, so I'm confused about how this is supposed > > > to work. > > > > Actually current mainline have a bug for this. So I tried to use another > > special patch[1] for it in v8. > > If you're fixing a bug in mainline, I'd prefer to see that as a separate > patch. > > > But the issue is not critical since MediaTek multimedia consumer(v4l2 > > and drm) don't call iommu_iova_to_phys currently. > > > > > > > > The way I would like this quirk to work is that the io-pgtable code > > > basically sets bit 9 in the pte when bit 32 is set in the physical address, > > > and sets bit 4 in the pte when bit 33 is set in the physical address. It > > > would then do the opposite when converting a pte to a physical address. > > > > > > That way, your driver can call the page table code directly with the high > > > addresses and we don't have to do any manual offsetting or range checking > > > in the page table code. > > > > In this case, the mt8183 can work successfully while the "4gb > > mode"(mt8173/mt2712) can not. > > > > In the "4gb mode", As the remap relationship above, we should always add > > bit32 in pte as we did in [2]. and need add bit32 in the > > "iova_to_phys"(Not always add.). That means the "4gb mode" has a special > > flow: > > a. Always add bit32 in paddr_to_iopte. > > b. Add bit32 only when PA < 0x40000000 in iopte_to_paddr. > > I think this is probably at the heart of my misunderstanding. What is so > special about PAs (is this HW PA or CPU PA?) below 0x40000000? Is this RAM > or something else? SRAM and HW register that IOMMU can not access. (sorry, My mailbox has something wrong.)