Subject: Re: [PATCH V5 RESEND 2/3] iommu/hisilicon: Add hi6220-SoC smmu driver
To: Joerg Roedel <joro@8bytes.org>
References: <1447986309-47548-1-git-send-email-puck.chen@hisilicon.com>
 <1447986309-47548-3-git-send-email-puck.chen@hisilicon.com>
 <20151127120203.GI24300@8bytes.org>
CC: <iommu@lists.linux-foundation.org>, <linux-kernel@vger.kernel.org>,
        <robh+dt@kernel.org>, <pawel.moll@arm.com>, <mark.rutland@arm.com>,
        <ijc+devicetree@hellion.org.uk>, <devicetree@vger.kernel.org>,
        <puck.chen@aliyun.com>, <w.f@huawei.com>, <xuwei5@hisilicon.com>,
        <guodong.xu@linaro.org>, <arnd@linaro.org>,
        <haojian.zhuang@linaro.org>
From: chenfeng <puck.chen@hisilicon.com>
Message-ID: <56590F22.90105@hisilicon.com>
Date: Sat, 28 Nov 2015 10:19:14 +0800
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On 2015/11/27 20:02, Joerg Roedel wrote:
> On Fri, Nov 20, 2015 at 10:25:08AM +0800, Chen Feng wrote:
>> +config HI6220_IOMMU
>> +	bool "Hi6220 IOMMU Support"
>> +	depends on ARM64
>> +	select IOMMU_API
>> +	select IOMMU_IOVA
>> +	help
>> +	  Enable IOMMU Driver for hi6220 SoC. The IOMMU API and IOMMU IOVA
>> +	  is also selected.
> 
> The last sentence is of little help for the user. Better put the reasons
> in here when a user should select this option.
> 
>> +	/*set axi id*/
> 
> Coding style nit: Please write these oneline comments with spaces, like
> this:
> 
> 	/* set axi id */
> 

learned,Thanks.
>> +static int hi6220_smmu_attach_dev(struct iommu_domain *domain,
>> +				  struct device *dev)
>> +{
>> +	dev->archdata.iommu = &iova_allocator;
>> +
>> +	return 0;
>> +}
>> +
>> +static void hi6220_smmu_detach_dev(struct iommu_domain *domain,
>> +				   struct device *dev)
>> +{
>> +	dev->archdata.iommu = NULL;
>> +}
> 
> This basically means that this driver only supports one domain, right?
yes.
> That is not compatible with the iommu-api requirements.
> 
> You need to create an iommu-group per smmu in your system and put all
> devices translated by this smmu in that group. And then you must change
> your code to allow attaching/detaching this iommu-group to different
> domains.
> 
I read the code,I am confused about these concepts.
In my opinion,
IOMMU-Domain: The masters in one domain share the same iova space. Is that right?
IOMMU-GROUP: As you mentioned up,all devices translated by this smmu should be into one group.
I can do this. But if there is only on domain in the system, how can I attaching/detaching the group
to different domains.

I think I have something wrong with these concepts.

Could you help to give me some suggestions.

> 
> 	Joerg
> 
> 
> .
> 

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