linux-kernel - Re: [Patch Part2 v4 21/31] PCI/MSI: enhance PCI MSI core to support hierarchy irqdomain

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Message-ID: <545AFF01.8000502@huawei.com>
Date:	Thu, 6 Nov 2014 12:54:25 +0800
From:	Yijing Wang <wangyijing@...wei.com>
To:	Bjorn Helgaas <bhelgaas@...gle.com>
CC:	Jiang Liu <jiang.liu@...ux.intel.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Randy Dunlap <rdunlap@...radead.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Borislav Petkov <bp@...en8.de>,
	Grant Likely <grant.likely@...aro.org>,
	Marc Zyngier <marc.zyngier@....com>,
	Yingjoe Chen <yingjoe.chen@...iatek.com>,
	Matthias Brugger <matthias.bgg@...il.com>,
	Alexander Gordeev <agordeev@...hat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Tony Luck" <tony.luck@...el.com>, Joerg Roedel <joro@...tes.org>,
	"Greg Kroah-Hartman" <gregkh@...uxfoundation.org>,
	"x86@...nel.org" <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	linux-arm <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [Patch Part2 v4 21/31] PCI/MSI: enhance PCI MSI core to support
 hierarchy irqdomain

On 2014/11/6 12:10, Bjorn Helgaas wrote:
> On Wed, Nov 5, 2014 at 6:58 PM, Yijing Wang <wangyijing@...wei.com> wrote:
> 
>>>> +{
>>>> +    return (irq_hw_number_t)msidesc->msi_attrib.entry_nr |
>>>> +            PCI_DEVID(pdev->bus->number, pdev->devfn) << 11 |
>>>> +            (pci_domain_nr(pdev->bus) & 0xFFFFFFFF) << 27;
>>>
>>> Where does this bit layout come from?  Is this defined in the spec
>>> somewhere?  A reference would help.
>>
>> Currently, more and more Non-PCI device use MSI(or similar MSI mechanism), like DMAR fault irq
>> and HPET FSB irq. And we have to add additional code to support the MSI capability.
>> So I hope we can decouple MSI code and PCI code, then we can unify all MSI(or Message Based interrupt)
>> in one framework.
> 
> Was that supposed to answer my question?  If so, I didn't understand
> how it explains where the bit layout came from.

No, that's just my concern. Because this function uses the pci device id,
but more and more Non-PCI devices use MSI.

> 
> Bjorn
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> .
> 


-- 
Thanks!
Yijing

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