Message-ID: <5A5F474C.8020606@rock-chips.com>
Date: Wed, 17 Jan 2018 20:53:32 +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: [PATCH v2 09/13] iommu/rockchip: Use iommu_group_get_for_dev()
 for add_device
References: <20180116132540.18939-1-jeffy.chen@rock-chips.com> <20180116132540.18939-10-jeffy.chen@rock-chips.com> <4c1b2469-9a32-c6ca-522f-73143b0fa618@arm.com> <5A5F45DA.5000104@rock-chips.com>
In-Reply-To: <5A5F45DA.5000104@rock-chips.com>
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Sender: linux-kernel-owner@vger.kernel.org

On 01/17/2018 08:47 PM, JeffyChen wrote:
>>>
>>> +static struct iommu_group *rk_iommu_device_group(struct device *dev)
>>> +{
>>> +    struct iommu_group *group;
>>> +    int ret;
>>> +
>>> +    group = iommu_group_get(dev);
>>> +    if (!group) {
>>
>> This check is pointless - if dev->iommu_group were non-NULL you wouldn't
>> have been called in the first place.
> right, it's allocated in the probe.
oops, sorry, i see, this is not needed because device_group() is only be 
called when iommu_group_get() returns NULL