Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753869AbbG0Pse (ORCPT ); Mon, 27 Jul 2015 11:48:34 -0400 Received: from foss.arm.com ([217.140.101.70]:54078 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753316AbbG0Psc (ORCPT ); Mon, 27 Jul 2015 11:48:32 -0400 Date: Mon, 27 Jul 2015 16:48:31 +0100 From: Will Deacon To: Yong Wu Cc: Joerg Roedel , Thierry Reding , Mark Rutland , Matthias Brugger , Robin Murphy , Daniel Kurtz , Tomasz Figa , Lucas Stach , Rob Herring , Catalin Marinas , "linux-mediatek@lists.infradead.org" , Sasha Hauer , "srv_heupstream@mediatek.com" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "iommu@lists.linux-foundation.org" , "pebolle@tiscali.nl" , "arnd@arndb.de" , "mitchelh@codeaurora.org" , "cloud.chou@mediatek.com" , "frederic.chen@mediatek.com" Subject: Re: [PATCH v3 5/6] iommu/mediatek: Add mt8173 IOMMU driver Message-ID: <20150727154830.GK3358@arm.com> References: <1437037475-9065-1-git-send-email-yong.wu@mediatek.com> <1437037475-9065-6-git-send-email-yong.wu@mediatek.com> <20150721145910.GG31095@arm.com> <1437716593.23932.73.camel@mhfsdcap03> <20150724165509.GD21177@arm.com> <1437971071.25925.24.camel@mhfsdcap03> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1437971071.25925.24.camel@mhfsdcap03> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1681 Lines: 40 On Mon, Jul 27, 2015 at 05:24:31AM +0100, Yong Wu wrote: > On Fri, 2015-07-24 at 17:55 +0100, Will Deacon wrote: > > On Fri, Jul 24, 2015 at 06:43:13AM +0100, Yong Wu wrote: > > > On Tue, 2015-07-21 at 15:59 +0100, Will Deacon wrote: > > > > On Thu, Jul 16, 2015 at 10:04:34AM +0100, Yong Wu wrote: > > > > > +static void mtk_iommu_tlb_flush_all(void *cookie) > > > > > +{ > > > > > + struct mtk_iommu_domain *domain = cookie; > > > > > + void __iomem *base; > > > > > + > > > > > + base = domain->data->base; > > > > > + writel(F_INVLD_EN1 | F_INVLD_EN0, base + REG_MMU_INV_SEL); > > > > > + writel(F_ALL_INVLD, base + REG_MMU_INVALIDATE); > > > > > > > > This needs to be synchronous, so you probably want to call > > > > mtk_iommu_tlb_sync at the end. > > > > > > From our spec, we have to wait until HW done after tlb flush range. > > > But it don't need wait after tlb flush all. > > > so It isn't necessary to add mtk_iommu_tlb_sync in tlb_flush_all here. > > > > Okey doke, but I'm surprised you don't need a subsequent DSB or read-back. > > What if the writel is buffered on the way to the IOMMU? > > Then I change to this: > //========== > writel_relaxed(F_INVLD_EN1 | F_INVLD_EN0, base + REG_MMU_INV_SEL); > writel_relaxed(F_ALL_INVLD, base + REG_MMU_INVALIDATE); > dsb(ishst); > //=========== > dsb or mb(). which one is better here? I think you should use mb(); Will -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/