Messages in this thread | | | Date | Wed, 7 Oct 2015 13:08:40 -0700 | From | David Daney <> | Subject | Re: [PATCH v4 1/5] PCI: Add pci_bus_fixup_irqs(). |
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On 10/07/2015 12:44 PM, Bjorn Helgaas wrote: > Hi David, > > On Fri, Oct 02, 2015 at 11:43:59AM -0700, David Daney wrote: >> From: David Daney <david.daney@cavium.com> >> >> pci_bus_fixup_irqs() works like pci_fixup_irqs(), except it only does >> the fixups for devices on the specified bus. >> >> Follow-on patch will use the new function. >> >> Signed-off-by: David Daney <david.daney@cavium.com> >> --- >> No change from v2. >> >> drivers/pci/setup-irq.c | 30 ++++++++++++++++++++++++++++++ >> include/linux/pci.h | 4 ++++ >> 2 files changed, 34 insertions(+) >> >> diff --git a/drivers/pci/setup-irq.c b/drivers/pci/setup-irq.c >> index 95c225b..189ad17 100644 >> --- a/drivers/pci/setup-irq.c >> +++ b/drivers/pci/setup-irq.c >> @@ -66,3 +66,33 @@ void pci_fixup_irqs(u8 (*swizzle)(struct pci_dev *, u8 *), >> pdev_fixup_irq(dev, swizzle, map_irq); >> } >> EXPORT_SYMBOL_GPL(pci_fixup_irqs); >> + >> +struct pci_bus_fixup_cb_info { >> + u8 (*swizzle)(struct pci_dev *, u8 *); >> + int (*map_irq)(const struct pci_dev *, u8, u8); >> +}; >> + >> +static int pci_bus_fixup_irq_cb(struct pci_dev *dev, void *arg) >> +{ >> + struct pci_bus_fixup_cb_info *info = arg; >> + >> + pdev_fixup_irq(dev, info->swizzle, info->map_irq); >> + return 0; >> +} >> + >> +/* >> + * Fixup the irqs only for devices on the given bus using supplied >> + * swizzle and map_irq function pointers >> + */ >> +void pci_bus_fixup_irqs(struct pci_bus *bus, >> + u8 (*swizzle)(struct pci_dev *, u8 *), >> + int (*map_irq)(const struct pci_dev *, u8, u8)) >> +{ >> + struct pci_bus_fixup_cb_info info; >> + >> + info.swizzle = swizzle; >> + info.map_irq = map_irq; >> + pci_walk_bus(bus, pci_bus_fixup_irq_cb, &info); > > I don't like the existing pci_fixup_irqs(), so by transitivity, I > don't like pci_bus_fixup_irqs() either.
We are in agreement with respect to this point.
> The problem is that in both > cases this is a one-time pass over the tree, so we don't handle > hot-added devices correctly. > > I think we need to get rid of pci_fixup_irqs() and somehow integrate > it into the pci_device_add() path, where it would be done once for > every device we enumerate.
I also agree with this point.
> If we did that, I don't think you would > need to add pci_bus_fixup_irqs(), would you?
Nope.
However, such a change is essentially untestable by me. So, I didn't attempt it. pci_fixup_irqs() is used by alpha, arm, m68k, mips, sh, sparc, tile, unicore32 and other things as well. If the core pci_device_add() code were to suddenly start doing the fixup, there would be the potential to break all these things I cannot test.
The new pci_bus_fixup_irqs() is really an optimization so that if we have multiple buses created by pci-host-generic.c, that we only iterate over each device once. I believe that pci-host-generic.c would still operate without these patches 1/5 and 2/5, and could test that if you are OK with the remaining three patches. Or we could merge all 5 and live a while longer with the ugliness that is already there.
David Daney
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