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Date: Thu, 13 Nov 2014 11:27:39 +0000 From: Marc Zyngier <marc.zyngier@....com> To: Thomas Gleixner <tglx@...utronix.de> CC: Jiang Liu <jiang.liu@...ux.intel.com>, Bjorn Helgaas <bhelgaas@...gle.com>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, 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@...aro.org" <grant.likely@...aro.org>, Yingjoe Chen <yingjoe.chen@...iatek.com>, Matthias Brugger <matthias.bgg@...il.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>, Yijing Wang <wangyijing@...wei.com>, "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-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org> Subject: Re: [RFC Part4 v1 00/17] Refine support of non-PCI-compliant Message Hi Thomas, On 12/11/14 14:46, Thomas Gleixner wrote: > On Wed, 12 Nov 2014, Marc Zyngier wrote: >> This patch introduces two optionnal fields to the msi_chip structure: >> - a pointer to an irq domain, describing the MSI domain associated >> with this msi_chip. To be populated with msi_create_irq_domain. >> - a domain_alloc_irqs() callback that has the same purpose as >> arch_setup_msi_irqs(), with the above domain as an additional >> parameter. >> >> If both of these fields are non-NULL, then domain_alloc_irqs() is >> called, bypassing the setup_irq callback. This allows the MSI driver >> to use the domain stacking feature without mandating core support in >> the architecture. > > I'd rather have the callback in the irqdomain itself. Along with a > callback to free the interrupts. > > AFAICT is msi_chip more or less a wrapper around the actual MSI irq > domain. So we rather move towards assigning irqdomain to the pci bus > and get rid of msi_chip instead of adding another level of obscure > indirection through msi_chip. I can see that putting the irq domain at the bus level makes a lot of sense (assuming nobody tries to have multiple MSI controllers per bus...). So I'm starting with something like this: diff --git a/include/linux/irqdomain.h b/include/linux/irqdomain.h index 640a1ec..07e50fc 100644 --- a/include/linux/irqdomain.h +++ b/include/linux/irqdomain.h @@ -41,6 +41,7 @@ struct irq_domain; struct of_device_id; struct irq_chip; struct irq_data; +struct device; /* Number of irqs reserved for a legacy isa controller */ #define NUM_ISA_INTERRUPTS 16 @@ -76,6 +77,10 @@ struct irq_domain_ops { unsigned int nr_irqs); void (*activate)(struct irq_domain *d, struct irq_data *irq_data); void (*deactivate)(struct irq_domain *d, struct irq_data *irq_data); + int (*prepare_alloc_irqs)(struct irq_domain *d, struct device *dev, + unsigned int nr_irqs, int type); + int (*cleanup_free_irqs)(struct irq_domain *d, struct device *dev, + unsigned int virq, unsigned int nr_irqs); #endif }; How do you see this behaving? At the moment, I have the "prepare" callback directly calling into pci_msi_domain_alloc_irqs() so that the irqs get created, but I have the nagging feeling that it's not what you want... ;-) The main issue I can see is that if more than one domain in the stack implements that, who gets to call pci_msi_domain_alloc_irqs? If we try to decouple those two, there is a problem with the creation of the intermediate structure (the irq_alloc_info that's in Jiang's patches), as this is a arch/driver/whatever specific structure. For reference, I've pushed out my current branch (very much a work in progress): http://git.kernel.org/cgit/linux/kernel/git/maz/arm-platforms.git/log/?h=irq/branch-from-hell The commits related to this discussion are: http://git.kernel.org/cgit/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/branch-from-hell&id=56ea48e6389fe461cb3ddf01e19afcdcd8f12f66 and http://git.kernel.org/cgit/linux/kernel/git/maz/arm-platforms.git/commit/?h=irq/branch-from-hell&id=855ab8b937967854dd070de2d0aaa07639e19526 as well as the code making use of that: http://git.kernel.org/cgit/linux/kernel/git/maz/arm-platforms.git/tree/drivers/irqchip/irq-gic-v3-its.c?h=irq/branch-from-hell&id=9f8ed988c2411831b7512006642e484c151e9a7a#n1184 Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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