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

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Message-ID: <20150721145910.GG31095@arm.com>
Date:	Tue, 21 Jul 2015 15:59:10 +0100
From:	Will Deacon <will.deacon@....com>
To:	Yong Wu <yong.wu@...iatek.com>
Cc:	Joerg Roedel <joro@...tes.org>,
	Thierry Reding <treding@...dia.com>,
	Mark Rutland <Mark.Rutland@....com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Robin Murphy <Robin.Murphy@....com>,
	Daniel Kurtz <djkurtz@...gle.com>,
	Tomasz Figa <tfiga@...gle.com>,
	Lucas Stach <l.stach@...gutronix.de>,
	Rob Herring <robh+dt@...nel.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"linux-mediatek@...ts.infradead.org" 
	<linux-mediatek@...ts.infradead.org>,
	Sasha Hauer <kernel@...gutronix.de>,
	"srv_heupstream@...iatek.com" <srv_heupstream@...iatek.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"iommu@...ts.linux-foundation.org" <iommu@...ts.linux-foundation.org>,
	"pebolle@...cali.nl" <pebolle@...cali.nl>,
	"arnd@...db.de" <arnd@...db.de>,
	"mitchelh@...eaurora.org" <mitchelh@...eaurora.org>,
	"cloud.chou@...iatek.com" <cloud.chou@...iatek.com>,
	"frederic.chen@...iatek.com" <frederic.chen@...iatek.com>
Subject: Re: [PATCH v3 5/6] iommu/mediatek: Add mt8173 IOMMU driver

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.

> +}
> +
> +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.

Will
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