Date: Thu, 6 Nov 2014 11:30:47 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Jiang Liu <jiang.liu@linux.intel.com>
cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Randy Dunlap <rdunlap@infradead.org>, Yinghai Lu <yinghai@kernel.org>,
        Borislav Petkov <bp@alien8.de>, Grant Likely <grant.likely@linaro.org>,
        Marc Zyngier <marc.zyngier@arm.com>,
        Yingjoe Chen <yingjoe.chen@mediatek.com>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        Yijing Wang <wangyijing@huawei.com>,
        Alexander Gordeev <agordeev@redhat.com>,
        Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Tony Luck <tony.luck@intel.com>, Joerg Roedel <joro@8bytes.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Suravee Suthikulanit <suravee.suthikulpanit@amd.com>, x86@kernel.org,
        LKML <linux-kernel@vger.kernel.org>, linux-pci@vger.kernel.org,
        linux-acpi@vger.kernel.org, LAK <linux-arm-kernel@lists.infradead.org>
Subject: Re: [Patch Part2 v4 21/31] PCI/MSI: enhance PCI MSI core to support
 hierarchy irqdomain
In-Reply-To: <alpine.DEB.2.11.1411061023400.24960@nanos>
Message-ID: <alpine.DEB.2.11.1411061110550.24960@nanos>
References: <1415102525-9898-1-git-send-email-jiang.liu@linux.intel.com> <1415102525-9898-22-git-send-email-jiang.liu@linux.intel.com> <alpine.DEB.2.11.1411061023400.24960@nanos>
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On Thu, 6 Nov 2014, Thomas Gleixner wrote:
> On Tue, 4 Nov 2014, Jiang Liu wrote:
> > +#ifdef	CONFIG_PCI_MSI_IRQ_DOMAIN
> > +static inline irq_hw_number_t
> > +msi_get_hwirq(struct pci_dev *pdev, struct msi_desc *msidesc)
> > +{
> > +	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;
> > +}
> > +
> > +static int msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
> > +			    unsigned int nr_irqs, void *arg)
> > +{
> > +	int i, ret;
> > +	irq_hw_number_t hwirq = arch_msi_irq_domain_get_hwirq(arg);
> > +
> > +	if (irq_find_mapping(domain, hwirq) > 0)
> > +		return -EEXIST;
> > +
> > +	ret = irq_domain_alloc_irqs_parent(domain, virq, nr_irqs, arg);
> > +	if (ret >= 0)
> > +		for (i = 0; i < nr_irqs; i++) {
> > +			irq_domain_set_hwirq_and_chip(domain, virq + i,
> > +					hwirq + i, &msi_chip, (void *)(long)i);
> 
> I think msi_chip being a global unique thing is problematic. It does
> not allow multi platform kernels to select a chip at boot time and it
> does not allow per domain chip implementations when you have multiple
> msi domains. Aside of that msi_chip is a pretty bad name for a global.
> 
> The solution is rather simple and msi is wide spread enough to justify
> that.
> 
> struct irqdomain_msi_data {
>        struct irq_chip       *irq_chip;
> };
> 
> We make that a struct so we can accomodate for other special things
> which might be domain rather than architecture specific. One
> obvious use case would be to hold the arch_msi_irq_domain_get/set_hwirq
> callbacks.

That needs to hand in the domain as an argument as well.

Thanks,

	tglx
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