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From: Jingoo Han <jg1.han@samsung.com>
To: 'Kishon Vijay Abraham I' <kishon@ti.com>
Cc: 'Bjorn Helgaas' <bhelgaas@google.com>, linux-pci@vger.kernel.org,
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	'Jingoo Han' <jg1.han@samsung.com>
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Subject: Re: [PATCH] PCI: designware: Add irq_create_mapping()
Date: Wed, 09 Oct 2013 19:49:15 +0900
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On Wednesday, October 09, 2013 7:27 PM, Kishon Vijay Abraham I wrote:
> On Wednesday 09 October 2013 03:35 PM, Jingoo Han wrote:
> > On Wednesday, October 09, 2013 6:48 PM, Kishon Vijay Abraham I wrote:
> >> On Wednesday 09 October 2013 02:47 PM, Jingoo Han wrote:
> >>> On Wednesday, October 09, 2013 6:06 PM, Kishon Vijay Abraham I wrote:
> >>>> On Wednesday 09 October 2013 01:39 PM, Jingoo Han wrote:
> >>>>> Without irq_create_mapping(), the correct irq number cannot be
> >>>>> provided. In this case, it makes problem such as NULL deference.
> >>>>> Thus, irq_create_mapping() should be added for MSI.
> >>>>>
> >>>>> Signed-off-by: Jingoo Han <jg1.han@samsung.com>
> >>>>> Cc: Kishon Vijay Abraham I <kishon@ti.com>
> >>>>> ---
> >>>>> Tested on Exynos5440.
> >>>>>
> >>>>>  drivers/pci/host/pcie-designware.c |   10 ++++------
> >>>>>  drivers/pci/host/pcie-designware.h |    1 +
> >>>>>  2 files changed, 5 insertions(+), 6 deletions(-)
> >>>>>
> >>>>> diff --git a/drivers/pci/host/pcie-designware.c b/drivers/pci/host/pcie-designware.c
> >>>>> index 8963017..e536bb6 100644
> >>>>> --- a/drivers/pci/host/pcie-designware.c
> >>>>> +++ b/drivers/pci/host/pcie-designware.c
> >>>>> @@ -237,6 +237,8 @@ static int assign_irq(int no_irqs, struct msi_desc *desc, int *pos)
> >>>>>  		}
> >>>>>  	}
> >>>>>
> >>>>> +	pp->msi_irq_start = irq_create_mapping(pp->irq_domain, 0);
> >>>>> +
> >>>>
> >>>> I think irq_create_mapping should be done for all the MSI irq lines instead of
> >>>> only the first line. So you might have to do for MAX_MSI_IRQS lines.
> >>
> >> Maybe it should be only till MAX_MSI_IRQS-1?
> 
> I meant something like this,
> 
> 	for (i = 0; i < MAX_MSI_IRQS; i++)
> 		irq_create_mapping(pp->irq_domain, i);
>
> That didn't give me any issues though.

However, no driver calls irq_create_mapping() like this.
For example, Tegra PCI driver gives 'hwirq' as single offset value
to irq_create_mapping() without any loop.

static int tegra_msi_setup_irq(struct msi_chip *chip, struct pci_dev *pdev,
                               struct msi_desc *desc)
{
	hwirq = tegra_msi_alloc(msi);
	irq = irq_create_mapping(msi->domain, hwirq);

Maybe, the following can be used, it uses 'pos0' as the offset value.

	pp->msi_irq_start = irq_create_mapping(pp->irq_domain, pos0);
	irq = pp->msi_irq_start;


Best regards,
Jingoo Han