linux-kernel - Re: [PATCH V5 RESEND 2/3] iommu/hisilicon: Add hi6220-SoC smmu driver

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Message-ID: <56590F22.90105@hisilicon.com>
Date:	Sat, 28 Nov 2015 10:19:14 +0800
From:	chenfeng <puck.chen@...ilicon.com>
To:	Joerg Roedel <joro@...tes.org>
CC:	<iommu@...ts.linux-foundation.org>, <linux-kernel@...r.kernel.org>,
	<robh+dt@...nel.org>, <pawel.moll@....com>, <mark.rutland@....com>,
	<ijc+devicetree@...lion.org.uk>, <devicetree@...r.kernel.org>,
	<puck.chen@...yun.com>, <w.f@...wei.com>, <xuwei5@...ilicon.com>,
	<guodong.xu@...aro.org>, <arnd@...aro.org>,
	<haojian.zhuang@...aro.org>
Subject: Re: [PATCH V5 RESEND 2/3] iommu/hisilicon: Add hi6220-SoC smmu driver



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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