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References: <1546318276-18993-1-git-send-email-yong.wu@mediatek.com> <1546318276-18993-5-git-send-email-yong.wu@mediatek.com>
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From:   Evan Green <evgreen@chromium.org>
Date:   Mon, 25 Feb 2019 15:54:25 -0800
Message-ID: <CAE=gft7R4tkR9hAif4izQi1J1QTcC0rUVyrLAnDdzu_RHV6yHA@mail.gmail.com>
Subject: Re: [PATCH 04/13] iommu/mediatek: Add device_link between the
 consumer and the larb devices
To:     Yong Wu <yong.wu@mediatek.com>
Cc:     Joerg Roedel <joro@8bytes.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Rob Herring <robh+dt@kernel.org>,
        Robin Murphy <robin.murphy@arm.com>,
        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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Sender: linux-kernel-owner@vger.kernel.org
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On Mon, Dec 31, 2018 at 8:52 PM Yong Wu <yong.wu@mediatek.com> wrote:
>
> MediaTek IOMMU don't have its power-domain. all the consumer connect
> with smi-larb, then connect with smi-common.
>
>         M4U
>          |
>     smi-common
>          |
>   -------------
>   |         |    ...
>   |         |
> larb1     larb2
>   |         |
> vdec       venc
>
> When the consumer works, it should enable the smi-larb's power which
> also need enable the smi-common's power firstly.
>
> Thus, First of all, use the device link connect the consumer and the
> smi-larbs. then add device link between the smi-larb and smi-common.
>
> This patch adds device_link between the consumer and the larbs.
>
> Suggested-by: Tomasz Figa <tfiga@chromium.org>
> Signed-off-by: Yong Wu <yong.wu@mediatek.com>
> ---
>  drivers/iommu/mtk_iommu.c    | 15 +++++++++++++--
>  drivers/iommu/mtk_iommu_v1.c | 14 ++++++++++++--
>  2 files changed, 25 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/iommu/mtk_iommu.c b/drivers/iommu/mtk_iommu.c
> index 202e41b..735ae8d 100644
> --- a/drivers/iommu/mtk_iommu.c
> +++ b/drivers/iommu/mtk_iommu.c
> @@ -247,6 +247,7 @@ static void mtk_iommu_config(struct mtk_iommu_data *data,
>         struct mtk_smi_larb_iommu    *larb_mmu;
>         unsigned int                 larbid, portid;
>         struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> +       struct device_link *link;
>         int i;
>
>         for (i = 0; i < fwspec->num_ids; ++i) {
> @@ -257,10 +258,20 @@ static void mtk_iommu_config(struct mtk_iommu_data *data,
>                 dev_dbg(dev, "%s iommu port: %d\n",
>                         enable ? "enable" : "disable", portid);
>
> -               if (enable)
> +               if (enable) {
>                         larb_mmu->mmu |= MTK_SMI_MMU_EN(portid);
> -               else
> +                       /* Link the consumer with the larb device(supplier) */
> +                       link = device_link_add(dev, larb_mmu->dev,
> +                                              DL_FLAG_PM_RUNTIME |
> +                                              DL_FLAG_AUTOREMOVE_CONSUMER);
> +                       if (!link) {
> +                               dev_err(dev, "Unable to link %s\n",
> +                                       dev_name(larb_mmu->dev));
> +                               return;

The return is a little odd here, given that you don't return an error
and this function doesn't do anything else. If it's non-fatal that
this link didn't get set up, then remove the return. If it is fatal,
then return an error code.

> +                       }
> +               } else {
>                         larb_mmu->mmu &= ~MTK_SMI_MMU_EN(portid);
> +               }
>         }
>  }
>
> diff --git a/drivers/iommu/mtk_iommu_v1.c b/drivers/iommu/mtk_iommu_v1.c
> index 9386aee..022bad9 100644
> --- a/drivers/iommu/mtk_iommu_v1.c
> +++ b/drivers/iommu/mtk_iommu_v1.c
> @@ -201,6 +201,7 @@ static void mtk_iommu_config(struct mtk_iommu_data *data,
>         struct mtk_smi_larb_iommu    *larb_mmu;
>         unsigned int                 larbid, portid;
>         struct iommu_fwspec *fwspec = dev_iommu_fwspec_get(dev);
> +       struct device_link *link;
>         int i;
>
>         for (i = 0; i < fwspec->num_ids; ++i) {
> @@ -211,10 +212,19 @@ static void mtk_iommu_config(struct mtk_iommu_data *data,
>                 dev_dbg(dev, "%s iommu port: %d\n",
>                         enable ? "enable" : "disable", portid);
>
> -               if (enable)
> +               if (enable) {
>                         larb_mmu->mmu |= MTK_SMI_MMU_EN(portid);
> -               else
> +                       link = device_link_add(dev, larb_mmu->dev,
> +                                              DL_FLAG_PM_RUNTIME |
> +                                              DL_FLAG_AUTOREMOVE_CONSUMER);
> +                       if (!link) {
> +                               dev_err(dev, "Unable to link %s\n",
> +                                       dev_name(larb_mmu->dev));
> +                               return;

Same for this one.

> +                       }
> +               } else {
>                         larb_mmu->mmu &= ~MTK_SMI_MMU_EN(portid);
> +               }
>         }
>  }
>
> --
> 1.9.1
>