linux-kernel - Re: [PATCH] PCI: pcie-rcar: Fix OF node passed to MSI irq domain

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Message-ID: <20151123101521.07e8dc9b@arm.com>
Date:	Mon, 23 Nov 2015 10:15:21 +0000
From:	Marc Zyngier <marc.zyngier@....com>
To:	Phil Edworthy <phil.edworthy@...esas.com>
Cc:	Thierry Reding <treding@...dia.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Wolfram Sang <wsa@...-dreams.de>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Simon Horman <horms@...ge.net.au>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"linux-sh@...r.kernel.org" <linux-sh@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Ley Foon Tan <lftan@...era.com>,
	Jingoo Han <jg1.han@...sung.com>
Subject: Re: [PATCH] PCI: pcie-rcar: Fix OF node passed to MSI irq domain

On Mon, 23 Nov 2015 09:44:10 +0000
Phil Edworthy <phil.edworthy@...esas.com> wrote:

> Hi Marc,
> 
> On 20 November 2015 09:49, Marc Zyngier wrote:
> > On 18/11/15 18:01, Phil Edworthy wrote:
> > > Hi Marc,
> > >
> > > On 16 November 2015 18:31, Marc Zyngier wrote:
> > >> On 13/11/15 09:36, Phil Edworthy wrote:
> > > <snip>
> > >>> Since the stack trace doesn't help that much I added some tracing:
> > >>> pci_msi_setup_msi_irqs()
> > >>>   calls pci_msi_get_domain()
> > >>>     calls dev_get_msi_domain(), gets a non-NULL domain.
> > >>> pci_msi_setup_msi_irqs()
> > >>>   calls pci_msi_domain_alloc_irqs()
> > >>>     calls msi_domain_alloc_irqs()
> > >>> msi_domain_alloc_irqs:273: ops=ffffffc03193a810
> > >>> msi_domain_alloc_irqs:274: ops->msi_check=ffffffc031161418
> > >>> systemd-udevd[1311]: undefined instruction: pc=ffffffc03116141c
> > >>> That looks to me as though msi_check is off pointing to the weeds.
> > >>
> > >> So the next step is to find out who initializes msi_check. Assuming
> > >> someone does...
> > > Nothing initializes msi_check...
> > >
> > >
> > >>> By passing a NULL domain into irq_domain_add_linear() you get:
> > >>> pci_msi_setup_msi_irqs()
> > >>>   calls pci_msi_get_domain()
> > >>>     calls dev_get_msi_domain(), gets a NULL domain.
> > >>>     calls arch_setup_msi_irq()
> > >>> All ok then.
> > >>
> > >> Yes, because you're sidestepping the issue. Any chance you could dig a
> > >> bit deeper? I'd really like to nail this one down (before we convert
> > >> your PCI driver to the right API... ;-).
> > > The problem appears to be that when the pci host driver enables msi
> > > it calls the following:
> > > 	msi->domain = irq_domain_add_linear(pcie->dev->of_node,
> > INT_PCI_MSI_NR,
> > > 					    &msi_domain_ops, &msi->chip);
> > > The last arg is documented as:
> > > * @host_data: Controller private data pointer
> > > In _irq_domain_add() this ptr is stored in struct irq_domain's host_data.
> > >
> > > However, msi_domain_alloc_irqs() expects host_data to be a ptr to a
> > > struct msi_domain_info.
> > >
> > > It seems that a number of other pci host drivers do the same, so I am
> > > surprised that no one else has seen this.
> > 
> > Can you please give this hack a go and let me know if that helps?
> Works for me!

Cool. I'll post a patch with your Reported-by/Tested-by later today.

Thanks a lot.

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