From: Phil Edworthy <phil.edworthy@renesas.com>
To: Marc Zyngier <marc.zyngier@arm.com>
CC: Thierry Reding <treding@nvidia.com>, Bjorn Helgaas <bhelgaas@google.com>,
        Wolfram Sang <wsa@the-dreams.de>,
        Geert Uytterhoeven <geert@linux-m68k.org>,
        Simon Horman <horms@verge.net.au>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
        "linux-sh@vger.kernel.org" <linux-sh@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Ley Foon Tan <lftan@altera.com>, Jingoo Han <jg1.han@samsung.com>
Subject: RE: [PATCH] PCI: pcie-rcar: Fix OF node passed to MSI irq domain
Thread-Topic: [PATCH] PCI: pcie-rcar: Fix OF node passed to MSI irq domain
Thread-Index: AQHRFhpazS7O4def1E+1x+YbvdM7WJ6T04kggAASxwCAABC7IIAADPxggAFvZICAAZ8KAIABBYmAgADN4gCAANc20IAFULmAgAMTyRCAAqOygIAEtSvQ
Date: Mon, 23 Nov 2015 09:44:10 +0000
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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!

Many thanks
Phil

> diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c
> index 53e4632..7eaa4c8 100644
> --- a/drivers/pci/msi.c
> +++ b/drivers/pci/msi.c
> @@ -54,7 +54,7 @@ static int pci_msi_setup_msi_irqs(struct pci_dev *dev, int
> nvec, int type)
>  	struct irq_domain *domain;
> 
>  	domain = pci_msi_get_domain(dev);
> -	if (domain)
> +	if (domain && irq_domain_is_hierarchy(domain))
>  		return pci_msi_domain_alloc_irqs(domain, dev, nvec, type);
> 
>  	return arch_setup_msi_irqs(dev, nvec, type);
> @@ -65,7 +65,7 @@ static void pci_msi_teardown_msi_irqs(struct pci_dev *dev)
>  	struct irq_domain *domain;
> 
>  	domain = pci_msi_get_domain(dev);
> -	if (domain)
> +	if (domain && irq_domain_is_hierarchy(domain))
>  		pci_msi_domain_free_irqs(domain, dev);
>  	else
>  		arch_teardown_msi_irqs(dev);
> 
> --
> Jazz is not dead. It just smells funny...
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