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From:   Evan Green <evgreen@chromium.org>
Date:   Wed, 30 Jan 2019 10:29:33 -0800
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Subject: Re: [PATCH v5 08/20] iommu/mediatek: Add larb-id remapped support
To:     Yong Wu <yong.wu@mediatek.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Robin Murphy <robin.murphy@arm.com>,
        Rob Herring <robh+dt@kernel.org>,
        Tomasz Figa <tfiga@google.com>,
        Will Deacon <will.deacon@arm.com>,
        linux-mediatek@lists.infradead.org, srv_heupstream@mediatek.com,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
        linux-arm-kernel@lists.infradead.org,
        iommu@lists.linux-foundation.org, Arnd Bergmann <arnd@arndb.de>,
        yingjoe.chen@mediatek.com, youlin.pei@mediatek.com,
        Nicolas Boichat <drinkcat@chromium.org>
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On Mon, Dec 31, 2018 at 7:58 PM Yong Wu <yong.wu@mediatek.com> wrote:
>
> The larb-id may be remapped in the smi-common, this means the
> larb-id reported in the mtk_iommu_isr isn't the real larb-id,
>
> Take mt8183 as a example:
>                        M4U
>                         |
> ---------------------------------------------
> |               SMI common                  |
> -0-----7-----5-----6-----1-----2------3-----4- <- Id remapped
>  |     |     |     |     |     |      |     |
> larb0 larb1 IPU0  IPU1 larb4 larb5  larb6  CCU
> disp  vdec  img   cam   venc  img    cam
> As above, larb0 connects with the id 0 in smi-common.
>           larb1 connects with the id 7 in smi-common.
>           ...
> If the larb-id reported in the isr is 7, actually it's larb1(vdec).
> In order to output the right larb-id in the isr, we add a larb-id
> remapping relationship in this patch.
>
> If there is no this larb-id remapping in some SoCs, use the linear
> mapping array instead.
>
> This also is a preparing patch for mt8183.
>
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
>  drivers/iommu/mtk_iommu.c | 4 ++++
>  drivers/iommu/mtk_iommu.h | 2 ++
>  2 files changed, 6 insertions(+)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 847082c..eca1536 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -220,6 +220,8 @@ static irqreturn_t mtk_iommu_isr(int irq, void *dev_id)
>         fault_larb = F_MMU0_INT_ID_LARB_ID(regval);
>         fault_port = F_MMU0_INT_ID_PORT_ID(regval);
>
> +       fault_larb = data->plat_data->larbid_remap[fault_larb];
> +
>         if (report_iommu_fault(&dom->domain, data->dev, fault_iova,
>                                write ? IOMMU_FAULT_WRITE : IOMMU_FAULT_READ)) {
>                 dev_err_ratelimited(
> @@ -742,12 +744,14 @@ static int __maybe_unused mtk_iommu_resume(struct device *dev)
>         .m4u_plat     = M4U_MT2712,
>         .has_4gb_mode = true,
>         .has_bclk     = true,
> +       .larbid_remap = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9},
>  };
>
>  static const struct mtk_iommu_plat_data mt8173_data = {
>         .m4u_plat     = M4U_MT8173,
>         .has_4gb_mode = true,
>         .has_bclk     = true,
> +       .larbid_remap = {0, 1, 2, 3, 4, 5}, /* Linear mapping. */

I briefly considered bikeshedding about how to define these arrays in
a way that might save memory for linear-map devices, but then decided
this is fine.

Reviewed-by: Evan Green <evgreen@chromium.org>