From mboxrd@z Thu Jan  1 00:00:00 1970
From: thunder.leizhen@huawei.com (leizhen)
Date: Tue, 17 Jun 2014 15:57:28 +0800
Subject: [PATCH RFC v1 1/2] documentation/iommu: Add description of
 Hisilicon System MMU binding
In-Reply-To: <5537408.I9tiuCA96J@wuerfel>
References: <1401975430-2648-1-git-send-email-thunder.leizhen@huawei.com>
 <20140606110652.GB4116@e103592.cambridge.arm.com>
 <20140616162653.GV16758@arm.com> <5537408.I9tiuCA96J@wuerfel>
Message-ID: <539FF4E8.7010202@huawei.com>
To: linux-arm-kernel@lists.infradead.org
List-Id: linux-arm-kernel.lists.infradead.org

On 2014/6/17 0:42, Arnd Bergmann wrote:
> On Monday 16 June 2014 17:26:53 Will Deacon wrote:
>> On Fri, Jun 06, 2014 at 12:07:11PM +0100, Dave Martin wrote:
>>> On Fri, Jun 06, 2014 at 08:48:26AM +0200, Arnd Bergmann wrote:
>>>> On Thursday 05 June 2014 21:37:09 Zhen Lei wrote:
>>>>
>>>>> +- smmu-masters  : A list of phandles to device nodes representing bus
>>>>> +                  masters for which the SMMU can provide a translation
>>>>> +                  and their corresponding StreamIDs (see example below).
>>>>>
>>>>
>>>> We're currently in the process of defining a generic binding for IOMMUs.
>>>>
>>>> While the smmu-masters property was copied from an existing binding,
>>>> I think we will end up migrating away from that towards a common way
>>>> to express those things, and we shouldn't add another one doing this
>>>> in a nonstandard way. Please have a look at the latest discussion
>>>> about the iommu binding using #iommu-cells and a reference from the
>>>> master to the iommu and see if you can migrate your code to use that.
>>>
>>> Thanks for making this point -- I was going to do so yesterday but then
>>> hesitated due to uncertainty about whether this should really be a new
>>> driver.
>>>
>>> Either way, it would be very valuable at least to attempt to describe
>>> the Hisilicon SMMU implemenation using the new proposals, since that is
>>> a good test of how reusable the proposed generic binding actually is.
>>
>> If this ends up being an addition to the existing ARM SMMU driver, I'm
>> really not keen on using the new DT bindings. We're already stuck with
>> the old bindings for that driver -- supporting both old and new in the
>> same code only buys us maintenance headaches and pointless divergence
>> within the driver.
> 
> We have to migrate the driver to the new binding anyway, it may be
> a bit painful, but there are not really any users yet so there
> is a chance we can remove the nonstandard code at some point,
> perhaps in a few years.
> 
> 	Arnd
> 
> .
> 
My driver will base on arm-smmu, and I saw Will Deacon had agreed to you.
So me too.