Re: [RFC PATCH v2 06/22] xen/arm: its: Port ITS driver to xen

[Julien Grall <julien.grall.oss@gmail.com>]

Hi Vijay,

On 02/04/2015 09:25, Vijay Kilari wrote:
> On Wed, Apr 1, 2015 at 5:04 PM, Ian Campbell <ian.campbell@citrix.com> wrote:
>> On Thu, 2015-03-19 at 20:07 +0530, vijay.kilari@gmail.com wrote:
>>> From: Vijaya Kumar K <Vijaya.Kumar@caviumnetworks.com>
>>>
>>> This patch just makes ITS driver taken from linux
>>> compiles in xen environment.
>>
>> What is your intention wrt future updates to this driver?
>>
>> Are you intending to keep things in sync and import things from the
>> Linux side (similar to the smmu drviers) or are you taking the Linux
>> code as a starting point and intending that it then be maintained
>> independently as a Xen driver from then on?
>
> Yes, I intend to keep things in sync with Linux driver.
> I have kept most the code same as Linux side except removing unused code.


The result of this series shows that we diverge a lot from the original 
driver. We have lots of Xen specific code added and some interface has 
changed for our purpose.

For instance, removing unused code is not something we should do in sync 
driver because it's harder to backport patch (the context of the diff 
will unlikely be the same).

Furthermore, we may also want to change the way that completion is 
notified (see discussion on patch #13).

While it was a good thing to keep the SMMU driver sync with Linux (not 
much diff required), I think this would be a mistake for the ITS.

Regards,

-- 
Julien Grall