linux-kernel - Re: [PATCH 2/2] arm64: dts: juno: Describe the full GICv2m region

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Date:   Mon, 12 Feb 2018 18:26:09 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Robin Murphy <robin.murphy@....com>,
        Marc Zyngier <marc.zyngier@....com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Liviu Dudau <liviu.dudau@....com>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: [PATCH 2/2] arm64: dts: juno: Describe the full GICv2m region

Hi Robin,

On 12/02/18 18:22, Robin Murphy wrote:
> On 12/02/18 18:17, Sudeep Holla wrote:
>>
>>
>> On 07/02/18 14:32, Marc Zyngier wrote:
>>> From: Robin Murphy <robin.murphy@....com>
>>>
>>> Juno's GICv2m implementation consists of four frames providing 32
>>> interrupts each. Since it is possible to plug in enough PCIe endpoints
>>> to consume more than 32 MSIs, and the driver already has a bodge to
>>> handle multiple frames, let's expose the other three as well.
>>>
>>
>> Change on it own looks good. So if you want to merge via your tree:
>>
>> Acked-by: Sudeep Holla <sudeep.holla@....com>
>>
>> Let me know if you decide not to take it via your tree and you want me
>> to send it to arm-soc.
>>
>> On the side note I just noticed the Juno TRM[1] has 64k for each of
>> these MSI frames(page 3-24 section 3.3.5 Application memory map summary)
>>
>> I am not sure if TRM is wrong. This patch is just copying the 4k size
>> from frame 0 which got added with initial Juno DTS.
> 
> Depends what your point of view is: The address map allocates 64KB worth
> of space for the device, but the device itself only decodes the first
> 4KB of that. My view is that the DT is describing the actual devices,
> not the interconnect routing between them, so there's really no need to
> tell consumers to map known-useless empty space.
> 

Thanks for the clarification.

-- 
Regards,
Sudeep