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

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Message-ID: <PS1PR06MB1180D8114604DE8AC1125E96F5070@PS1PR06MB1180.apcprd06.prod.outlook.com>
Date:	Mon, 23 Nov 2015 09:44:10 +0000
From:	Phil Edworthy <phil.edworthy@...esas.com>
To:	Marc Zyngier <marc.zyngier@....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

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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