Re: [PATCH 2/6] PCI: generic: Only fixup irqs for bus we are creating.

[David Daney]

On 09/16/2015 03:32 AM, Lorenzo Pieralisi wrote:
> On Tue, Sep 15, 2015 at 06:49:24PM +0100, David Daney wrote:
> > On 09/15/2015 10:36 AM, Will Deacon wrote:
> > > Hi David,
> > >
> > > On Sat, Sep 12, 2015 at 12:21:55AM +0100, David Daney wrote:
> > > > From: David Daney <david.daney@xxxxxxxxxx>
> > > >
> > > > Use pci_walk_bus() to restrict the fixup irq actions to only the bus
> > > > being created.
> > > >
> > > > If we create multiple buses with pci-host-generic, or there are buses
> > > > created by other drivers, we don't want to call pci_fixup_irqs() which
> > > > operates on all devices, not just the devices on the bus being added.
> > > > The consequence is that either the fixups are done more than once, or
> > > > in some cases incorrect fixups could be applied.
> > > >
> > > > Signed-off-by: David Daney <david.daney@xxxxxxxxxx>
> > > > ---
> > > >    drivers/pci/host/pci-host-generic.c | 8 +++++++-
> > > >    1 file changed, 7 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/drivers/pci/host/pci-host-generic.c b/drivers/pci/host/pci-host-generic.c
> > > > index 265dd25..a0fb241 100644
> > > > --- a/drivers/pci/host/pci-host-generic.c
> > > > +++ b/drivers/pci/host/pci-host-generic.c
> > > > @@ -205,6 +205,12 @@ static int gen_pci_parse_map_cfg_windows(struct gen_pci *pci)
> > > >    	return 0;
> > > >    }
> > > >
> > > > +static int gen_pci_fixup_irq_cb(struct pci_dev *dev, void *arg)
> > > > +{
> > > > +	pdev_fixup_irq(dev, pci_common_swizzle, of_irq_parse_and_map_pci);
> > > > +	return 0;
> > > > +}
> > > > +
> > > >    static int gen_pci_probe(struct platform_device *pdev)
> > > >    {
> > > >    	int err;
> > > > @@ -262,7 +268,7 @@ static int gen_pci_probe(struct platform_device *pdev)
> > > >    		return -ENODEV;
> > > >    	}
> > > >
> > > > -	pci_fixup_irqs(pci_common_swizzle, of_irq_parse_and_map_pci);
> > > > +	pci_walk_bus(bus, gen_pci_fixup_irq_cb, NULL);
> > >
> > > Any chance we could put something in the core PCI code for this? I think
> > > any host controller wanting to work with arm64 is potentially going to
> > > run into the same problem.
> >
> > Good idea.
> >
> > I will move the walking code into setup-irq.c (the current home of
> > pci_fixup_irqs()), and make it part of patch 1/6.
>
> For arm64 we could even compile out pci_fixup_irqs() since the IRQ mapping
> is done in pcibios_add_device() through DT, I agree on CONFIG_ARM this
> needs fixing though, so yes, make it common code and patch all host
> controllers that make use of pci_fixup_irqs() since that's a common
> issue as far as I can see (ARM pcibios works around it by having a
> IRQ mapping function per bus and it provides an API to initialize
> multiple host controllers at once and fixing up IRQs before devices
> are added, still, for host controllers that do not use that
> functionality - eg drivers/pci/host/pcie-designware.c - if there are
> multiple host controllers instances we run into the same problem).

Patching up other PCI bus drivers would be deferred to a different patch 
set, as I have no way to test it.

> Side note: do you have any PCI host controller where mapping IRQs through
> of_irq_parse_and_map_pci() does not work ? If yes, why ?

The of_irq_parse_and_map_pci() call in arch/arm64/kernel/pci.c 
(pcibios_add_device) seems to work for me.

I did send a patch recently to make it quite emitting erroneous error 
messages for PCI devices that have no irq pin.

David Daney
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