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Date: Thu, 01 Mar 2018 19:14:10 +0800
From: JeffyChen <jeffy.chen@rock-chips.com>
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To: Robin Murphy <robin.murphy@arm.com>, linux-kernel@vger.kernel.org
CC: jcliang@chromium.org, xxm@rock-chips.com, tfiga@chromium.org,
        Heiko Stuebner <heiko@sntech.de>, linux-rockchip@lists.infradead.org,
        iommu@lists.linux-foundation.org, Joerg Roedel <joro@8bytes.org>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [RESEND PATCH v6 14/14] iommu/rockchip: Support sharing IOMMU
 between masters
References: <20180301101837.27969-1-jeffy.chen@rock-chips.com> <20180301101837.27969-15-jeffy.chen@rock-chips.com> <44efebd3-ab48-4e12-cf92-66b6563f7644@arm.com>
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Hi Robin,

On 03/01/2018 07:03 PM, Robin Murphy wrote:
>>
>> +static struct iommu_group *rk_iommu_device_group(struct device *dev)
>> +{
>> +    struct rk_iommu *iommu;
>> +
>> +    iommu = rk_iommu_from_dev(dev);
>> +
>> +    return iommu->group;
>
> Oops, seems I overlooked this in my previous review - it should really be:
>
>      return iommu_group_get(iommu->group);
>
> or the refcounting will be unbalanced on those future systems where it
> really will be called more than once.
>
hmmm, right, it should be return iommu_group_ref_get(iommu->group);

i was following omap iommu:
static struct iommu_group *omap_iommu_device_group(struct device *dev)
{
         struct omap_iommu_arch_data *arch_data = dev->archdata.iommu;
         struct iommu_group *group = ERR_PTR(-EINVAL);

         if (arch_data->iommu_dev)
                 group = arch_data->iommu_dev->group;

         return group;
}

will fix it too in the version.

> Robin.