linux-kernel - Re: [PATCH 18/21] iommu/mediatek: Add support for multi domain

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Message-ID: <20200723204729.GA823856@bogus>
Date:   Thu, 23 Jul 2020 14:47:29 -0600
From:   Rob Herring <robh@...nel.org>
To:     Yong Wu <yong.wu@...iatek.com>
Cc:     Joerg Roedel <joro@...tes.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Robin Murphy <robin.murphy@....com>,
        Will Deacon <will@...nel.org>,
        Evan Green <evgreen@...omium.org>,
        Tomasz Figa <tfiga@...gle.com>,
        linux-mediatek@...ts.infradead.org, srv_heupstream@...iatek.com,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        iommu@...ts.linux-foundation.org, youlin.pei@...iatek.com,
        Nicolas Boichat <drinkcat@...omium.org>, anan.sun@...iatek.com,
        cui.zhang@...iatek.com, chao.hao@...iatek.com,
        ming-fan.chen@...iatek.com
Subject: Re: [PATCH 18/21] iommu/mediatek: Add support for multi domain

On Sat, Jul 11, 2020 at 02:48:43PM +0800, Yong Wu wrote:
> Some HW IP(ex: CCU) require the special iova range. That means the
> iova got from dma_alloc_attrs for that devices must locate in his
> special range. In this patch, we allocate a special iova_range for
> each a special requirement and create each a iommu domain for each
> a iova_range.
> 
> meanwhile we still use one pagetable which support 16GB iova.
> 
> After this patch, If the iova range of a master is over 4G, the master
> should:
> a) Declare its special dma_ranges in its dtsi node. For example, If we
> preassign the iova 4G-8G for vcodec, then the vcodec dtsi node should:
> 	dma-ranges = <0x1 0x0 0x1 0x0 0x1 0x0>;  /* 4G ~ 8G */

BTW, dma-ranges should be in the parent node of the vcodec.

> b) Update the dma_mask:
>  dma_set_mask_and_coherent(dev, DMA_BIT_MASK(33));

This should happen for you automatically. The DMA PFN offset 
should also be 4GB here.

> 
> Signed-off-by: Yong Wu <yong.wu@...iatek.com>
> ---
>  drivers/iommu/mtk_iommu.c | 49 ++++++++++++++++++++++++++++++++-------
>  drivers/iommu/mtk_iommu.h |  3 ++-
>  2 files changed, 42 insertions(+), 10 deletions(-)