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From: Mitchel Humpherys <mitchelh@codeaurora.org>
To: <yong.wu@mediatek.com>
Cc: Rob Herring <robh+dt@kernel.org>, Joerg Roedel <joro@8bytes.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
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        Robin Murphy <robin.murphy@arm.com>,
        linux-arm-kernel@lists.infradead.org,
        Lucas Stach <l.stach@pengutronix.de>
Subject: Re: [PATCH 2/5] iommu/mediatek: Add mt8173 IOMMU driver
References: <1425638900-24989-1-git-send-email-yong.wu@mediatek.com>
	<1425638900-24989-3-git-send-email-yong.wu@mediatek.com>
Date: Fri, 06 Mar 2015 09:15:17 -0800
In-Reply-To: <1425638900-24989-3-git-send-email-yong.wu@mediatek.com> (yong
	wu's message of "Fri, 6 Mar 2015 18:48:17 +0800")
Message-ID: <vnkwwq2unj2y.fsf@mitchelh-linux.qualcomm.com>
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On Fri, Mar 06 2015 at 02:48:17 AM, <yong.wu@mediatek.com> wrote:
> From: Yong Wu <yong.wu@mediatek.com>
>
> This patch adds support for mediatek m4u (MultiMedia Memory Management Unit).
> Currently this only supports m4u gen 2 with 2 levels of page table on mt8173.

[...]

> +static int mtk_iommu_invalidate_tlb(const struct mtk_iommu_info *piommu,
> +				    int isinvall, unsigned int iova_start,
> +				    unsigned int iova_end)
> +{
> +	void __iomem *m4u_base = piommu->m4u_base;
> +	u32 val;
> +	u64 start, end;
> +
> +	start = sched_clock();
> +
> +	if (!isinvall) {
> +		iova_start = round_down(iova_start, SZ_4K);
> +		iova_end = round_up(iova_end, SZ_4K);
> +	}
> +
> +	val = F_MMU_INV_EN_L2 | F_MMU_INV_EN_L1;
> +
> +	writel(val, m4u_base + REG_INVLID_SEL);
> +
> +	if (isinvall) {
> +		writel(F_MMU_INV_ALL, m4u_base + REG_MMU_INVLD);
> +	} else {
> +		writel(iova_start, m4u_base + REG_MMU_INVLD_SA);
> +		writel(iova_end, m4u_base + REG_MMU_INVLD_EA);
> +		writel(F_MMU_INV_RANGE, m4u_base + REG_MMU_INVLD);
> +
> +		while (!readl(m4u_base + REG_MMU_CPE_DONE)) {
> +			end = sched_clock();
> +			if (end - start >= 100000000ULL) {
> +				dev_warn(piommu->dev, "invalid don't done\n");
> +				writel(F_MMU_INV_ALL, m4u_base + REG_MMU_INVLD);
> +			}
> +		};

Superfluous `;'.  Also, maybe you should be using readl_poll_timeout?

> +		writel(0, m4u_base + REG_MMU_CPE_DONE);
> +	}
> +
> +	return 0;
> +}



-Mitch

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