From mboxrd@z Thu Jan  1 00:00:00 1970
From: Julien Grall <julien.grall@citrix.com>
Subject: Re: [RFC PATCH v2 13/22] xen/arm: its: Add virtual ITS
 command support
Date: Mon, 4 May 2015 14:04:50 +0100
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To: Vijay Kilari <vijay.kilari@gmail.com>
Cc: Ian Campbell <ian.campbell@citrix.com>, Stefano Stabellini <stefano.stabellini@eu.citrix.com>, Prasun Kapoor <Prasun.Kapoor@caviumnetworks.com>, Vijaya Kumar K <vijaya.kumar@caviumnetworks.com>, Julien Grall <julien.grall@linaro.org>, Tim Deegan <tim@xen.org>, "xen-devel@lists.xen.org" <xen-devel@lists.xen.org>, Stefano Stabellini <stefano.stabellini@citrix.com>, manish.jaggi@caviumnetworks.com
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On 04/05/2015 13:58, Vijay Kilari wrote:
> On Thu, Apr 30, 2015 at 7:59 PM, Julien Grall <julien.grall@citrix.com> wrote:
>> Hi,
>>
>> On 30/04/15 14:47, Stefano Stabellini wrote:
>>>>>>
>>>>>> If the devid is not within this range, the ITS won't recognize the value and
>>>>>> won't be able to send the interrupt.
>>>>>>
>>>>>> So this is clearly not the right value.
>>>>>
>>>>> Sure, in that case the maximum value allowed by GITS_TYPER.Devbits.
>>>>> Vijay, what is the value of GITS_TYPER.Devbits on your platform?
>>>>
>>>> It is 21 bits
>>>
>>> I would imagine that 21 bits would be plenty to find an unused devid.
>>>
>>> Alternatively we could use an inexistent function of a real device, such
>>> as 00:00.1 (function 1 of the host bridge).
>>
>> As discussed IRL, this idea sounds good to me.
>>
>> Although I would be happy with any other way which ensure the devid is free.
>
> Has prototyped with 00.00.1 as device id. But I see that Dom0 boot is
> slow compared to polling mode. This could be because Dom0 has to keep
> trapping on creader to check if creader is updated or not.

How did you implement the interrupt mode? Could it be improve?

Regards,

-- 
Julien Grall