From mboxrd@z Thu Jan 1 00:00:00 1970 From: Will Deacon Subject: Re: [PATCH v3 5/6] iommu/mediatek: Add mt8173 IOMMU driver Date: Mon, 27 Jul 2015 16:48:31 +0100 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 Return-path: Content-Disposition: inline In-Reply-To: <1437971071.25925.24.camel@mhfsdcap03> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org 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-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , Sasha Hauer , "srv_heupstream-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org" , "pebolle-IWqWACnzNjzz+pZb47iToQ@public.gmane.org" "arnd-r2nGTMty4D4@public.gmane.org" List-Id: devicetree@vger.kernel.org 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 devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html