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Subject: Re: [PATCH v2 09/10] irqchip: ti-sci-inta: Add support for Interrupt
 Aggregator driver
To:     Marc Zyngier <marc.zyngier@arm.com>,
        Grygorii Strashko <grygorii.strashko@ti.com>,
        Lokesh Vutla <lokeshvutla@ti.com>
Cc:     Nishanth Menon <nm@ti.com>,
        Santosh Shilimkar <ssantosh@kernel.org>,
        Rob Herring <robh+dt@kernel.org>, tglx@linutronix.de,
        jason@lakedaemon.net,
        Linux ARM Mailing List <linux-arm-kernel@lists.infradead.org>,
        linux-kernel@vger.kernel.org, Tero Kristo <t-kristo@ti.com>,
        Sekhar Nori <nsekhar@ti.com>,
        Device Tree Mailing List <devicetree@vger.kernel.org>,
        Peter Ujfalusi <peter.ujfalusi@ti.com>
References: <20181018154017.7112-1-lokeshvutla@ti.com>
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 <b20127dc-be43-3b00-9960-663738df0069@arm.com>
 <9969f24c-cdb0-1f5c-d0f4-b1c1f587325c@ti.com>
 <86va5ssrfm.wl-marc.zyngier@arm.com>
 <2369ea50-55db-c97b-5b43-99d572c97dc9@ti.com>
 <da27ecc5-db32-cf3a-c194-962c44bc782f@arm.com>
 <18df8960-9165-ba50-2c25-9f00d32198e8@oracle.com>
 <e799646e-1fff-f96b-38e8-3d46b0160867@arm.com>
From:   Santosh Shilimkar <santosh.shilimkar@oracle.com>
Organization: Oracle Corporation
Message-ID: <2207fc72-22a6-b216-7b98-7c8c7768f002@oracle.com>
Date:   Wed, 31 Oct 2018 11:48:00 -0700
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On 10/31/2018 11:42 AM, Marc Zyngier wrote:
> On 31/10/18 18:38, Santosh Shilimkar wrote:
>> On 10/31/2018 11:21 AM, Marc Zyngier wrote:
>>> Hi Grygorii,
>>>
>>
>> [...]
>>
>>>
>>> Well, I'm convinced that we do not want a networking driver to be tied
>>> to an interrupt architecture, and that the two should be completely
>>> independent. But that's my own opinion. I can only see two solutions
>>> moving forward:
>>>
>>> 1) You make the IA a real interrupt controller that exposes real
>>> interrupts (one per event), and write your networking driver
>>> independently of the underlying interrupt architecture.
>>>
>>> 2) you make the IA an integral part of your network driver, not exposing
>>> anything outside of it, and limiting the interactions with the IR
>>> *through the standard IRQ API*. You duplicate this knowledge throughout
>>> the other client drivers.
>>>
>>> I believe that (2) would be a massive design mistake as it locks the
>>> driver to a single of the HW (and potentially a single revision of the
>>> firmware) while (1) gives you the required level of flexibility by
>>> hiding the whole event "concept" at a single location.
>>>
>>> Yes, (1) makes you rewrite your existing, out of tree drivers. Oh well...
>>>
>> My preference is also not tie the network driver with IA. BTW, this is
>> very standard functionality with other network drivers too. And this
>> is handled using MSI-X.
>>
>> So strong NO for 1) from me as well.
> 
> Err. Are you opposing to (1) or (2)? From the above, I cannot really
> tell... ;-)
> 
I mixed it up, sorry. I meant NO for (2), i.e No for making IA part of
the network driver.

Regards,
Santosh