Re: [PATCH v3 5/6] iommu/mediatek: Add mt8173 IOMMU driver

From: Yong Wu <yong.wu@mediatek.com>
To: Will Deacon <will.deacon@arm.com>
Cc: Joerg Roedel <joro@8bytes.org>,
	Thierry Reding <treding@nvidia.com>,
	Mark Rutland <Mark.Rutland@arm.com>,
	Matthias Brugger <matthias.bgg@gmail.com>,
	Robin Murphy <Robin.Murphy@arm.com>,
	Daniel Kurtz <djkurtz@google.com>, Tomasz Figa <tfiga@google.com>,
	Lucas Stach <l.stach@pengutronix.de>,
	Rob Herring <robh+dt@kernel.org>,
	Catalin Marinas <Catalin.Marinas@arm.com>,
	"linux-mediatek@lists.infradead.org" 
	<linux-mediatek@lists.infradead.org>,
	Sasha Hauer <kernel@pengutronix.de>,
	"srv_heupstream@mediatek.com" <srv_heupstream@mediatek.com>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
	"iommu@lists.linux-foundation.org"
	<iommu@lists.linux-foundation.org>,
	"pebolle@tiscali.nl" <pebolle@tiscali.nl>,
	"arnd@arndb.de" <arnd@arndb.de>,
	"mitchelh@codeaurora.org" <mitchelh@codeaurora.org>,
	"cloud.chou@mediatek.com" <cloud.chou@mediatek.com>,
	"frederic.chen@mediatek.com" <frederic.chen@mediatek.com>
Subject: Re: [PATCH v3 5/6] iommu/mediatek: Add mt8173 IOMMU driver
Date: Fri, 24 Jul 2015 13:43:13 +0800	[thread overview]
Message-ID: <1437716593.23932.73.camel@mhfsdcap03> (raw)
In-Reply-To: <20150721145910.GG31095@arm.com>

On Tue, 2015-07-21 at 15:59 +0100, Will Deacon wrote:
> Hi Yong Wu,
> 
> On Thu, Jul 16, 2015 at 10:04:34AM +0100, Yong Wu wrote:
> > This patch adds support for mediatek m4u (MultiMedia Memory Management
> > Unit).
> 
> [...]
> 
> > +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.

> 
> > +}
> > +
> > +static void mtk_iommu_tlb_add_flush(unsigned long iova, size_t size,
> > +                                   bool leaf, void *cookie)
> > +{
> > +       struct mtk_iommu_domain *domain = cookie;
> > +       void __iomem *base = domain->data->base;
> > +       unsigned int iova_start = iova, iova_end = iova + size - 1;
> > +
> > +       writel(F_INVLD_EN1 | F_INVLD_EN0, base + REG_MMU_INV_SEL);
> > +
> > +       writel(iova_start, base + REG_MMU_INVLD_START_A);
> > +       writel(iova_end, base + REG_MMU_INVLD_END_A);
> > +       writel(F_MMU_INV_RANGE, base + REG_MMU_INVALIDATE);
> 
> Why are you using writel instead of writel_relaxed? I asked this before
> but I don't think you replied.

Sorry, I didn't notice _relax last time. I will improve in next version.
Thanks very much.

> 
> Will