linux-kernel - Re: [RFC PATCH v0.2] PCI: Add support for tango PCIe host bridge

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Message-ID: <37cd6172-b04e-fcad-18fc-4fbb26cc611b@arm.com>
Date:   Wed, 12 Apr 2017 10:59:13 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Mason <slash.tmp@...e.fr>, Thomas Gleixner <tglx@...utronix.de>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Liviu Dudau <liviu.dudau@....com>,
        David Laight <david.laight@...lab.com>,
        linux-pci <linux-pci@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Thibaud Cornic <thibaud_cornic@...madesigns.com>,
        Phuong Nguyen <phuong_nguyen@...madesigns.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH v0.2] PCI: Add support for tango PCIe host bridge

On 12/04/17 10:50, Mason wrote:
> On 12/04/2017 10:08, Marc Zyngier wrote:
> 
>> On 11/04/17 18:52, Mason wrote:
>>
>>> so data->irq is the virq (30, 34, 35, 36)
>>> and data->hwirq is the domain hwirq (0, 524288, 524289, 524290)
>>>
>>> Is there a way to map hwirq 524288 to MSI 0, hwirq 524289 to MSI 1, etc?
>>
>> Why would you need to do such a thing?
>> - In MSI domain: IRQ34 -> hwirq 524288
>> - In foo domain: IRQ34 -> hwirq [whatever your driver has allocated]
>>
>> The data is already there, at your fingertips. Just deal with with your
>> "foo" irqchip.
> 
> OK, let me take a step back, I may have missed the forest for
> the trees.
> 
> In my original code (copied from the Altera driver) I unmasked
> a given MSI in the tango_irq_domain_alloc() function. You said
> this was the wrong place, as it should be done in the irqchip
> unmask callback. Did I understand correctly, so far?

Yes.

> I have registered custom mask/unmask callbacks for both irq_chips.

And that's *wrong*. I've repeatedly said that you only need to deal with
*your* irqchip. End of story. Nowhere else. Please leave the MSI irqchip
alone, it is very unlikely that you have to provide anything at all to it.

	M.
-- 
Jazz is not dead. It just smells funny...