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    SubjectRe: [PATCH v9 02/12] PCI: OF: Parse and map the IRQ when adding the PCI device.
    On Fri, Aug 15, 2014 at 11:30:52AM +0100, Liviu Dudau wrote:
    >On Fri, Aug 15, 2014 at 09:56:32AM +0100, Wei Yang wrote:
    >> On Thu, Aug 14, 2014 at 04:49:59PM +0100, Liviu Dudau wrote:
    >> >On Thu, Aug 14, 2014 at 03:58:04PM +0100, Wei Yang wrote:
    >> >> On Tue, Aug 12, 2014 at 05:25:15PM +0100, Liviu Dudau wrote:
    >> >> >Enhance the default implementation of pcibios_add_device() to
    >> >> >parse and map the IRQ of the device if a DT binding is available.
    >> >> >
    >> >> >Cc: Bjorn Helgaas <bhelgaas@google.com>
    >> >> >Cc: Grant Likely <grant.likely@linaro.org>
    >> >> >Cc: Rob Herring <robh+dt@kernel.org>
    >> >> >Signed-off-by: Liviu Dudau <Liviu.Dudau@arm.com>
    >> >> >---
    >> >> > drivers/pci/pci.c | 3 +++
    >> >> > 1 file changed, 3 insertions(+)
    >> >> >
    >> >> >diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
    >> >> >index 1c8592b..29d1775 100644
    >> >> >--- a/drivers/pci/pci.c
    >> >> >+++ b/drivers/pci/pci.c
    >> >> >@@ -17,6 +17,7 @@
    >> >> > #include <linux/spinlock.h>
    >> >> > #include <linux/string.h>
    >> >> > #include <linux/log2.h>
    >> >> >+#include <linux/of_pci.h>
    >> >> > #include <linux/pci-aspm.h>
    >> >> > #include <linux/pm_wakeup.h>
    >> >> > #include <linux/interrupt.h>
    >> >> >@@ -1453,6 +1454,8 @@ EXPORT_SYMBOL(pcim_pin_device);
    >> >> > */
    >> >> > int __weak pcibios_add_device(struct pci_dev *dev)
    >> >> > {
    >> >> >+ dev->irq = of_irq_parse_and_map_pci(dev, 0, 0);
    >> >> >+
    >> >> > return 0;
    >> >> > }
    >> >>
    >> >> Liviu,
    >> >>
    >> >> For this, my suggestion is to add arch dependent function to setup the irq
    >> >> line for pci devices. I can't find an obvious reason this won't work on other
    >> >> archs, but maybe this will hurt some of them?
    >> >
    >> >Hi Wei,
    >> >
    >> >I'm not sure I understand your point. Architectures that support OF will obviously
    >> >benefit from this common approach, and for the other ones the function is empty
    >> >so it will not change existing behaviour. If you are suggesting that I should
    >> >create a new API that each architecture could go and implement for setting up the
    >> >IRQ line then I would agree that it would be nice to have that, but the question
    >> >is how many architectures are outside OF that need this?
    >>
    >> My suggestion is to define the pcibios_add_device() for arm arch, like the one
    >> in arch/powerpc/kernel/pci-common.c. If my understanding is correct, this
    >> patch set address the pci bus setup mostly on arm arch.
    >
    >And also arm64 at the least.
    >
    >>
    >> For those archs not support OF, this function is empty and has no effect. I
    >> agree on this one.
    >>
    >> For those archs rely on OF, we still have two cases:
    >> 1. they would have implement this function like powerpc
    >
    >Actually, powerpc seems to be the only OF platform reimplementing this function.
    >s390 and x86 are not OF platforms.
    >
    >> 2. have other way to fix it up, otherwise how it works now?
    >
    >Don't forget that my patchset aims to replace existing house-made code with a more
    >generic version. When architectures and platforms switch to my code they will have
    >to add this back in their code if it's needed.
    >
    >> If my assumption is correct, this change will either have no effect, or fix up
    >> the irq line the second time. Not harmful, but not necessary.
    >
    >Well, it will become necessary as old code gets dismantled and converted towards
    >this patchset. To give you an example that I'm familiar with, for arch/arm the
    >host bridge drivers have moved into drivers/pci/host, but they still depend/use
    >the bios32 infrastructure that takes care of setting up the irq. When they switch
    >to my version they would have to go and debug the "irq not being assigned" issue
    >and it is quite likely that some of the people doing the conversion will complain
    >about my code rather than understanding the issue. What I'm trying to do is to
    >make switching to my patchset as painless as possible, with a cleanup to remove
    >redundant operations coming after the switchover.
    >

    This means this is a temporary version for the switchover period and will be
    reverted after switchover?

    >Does that sound like a reasonable plan?
    >
    >Best regards,
    >Liviu
    >
    >>
    >> I am not familiar with other arch, so the second case is my deduction. If this
    >> is not correct, please let me know.
    >>
    >> >
    >> >If I understood you correctly, it is a nice idea but slightly outside the scope
    >> >of my current patchset.
    >> >
    >> >Best regards,
    >> >Liviu
    >> >
    >> >>
    >> >> >
    >> >> >--
    >> >> >2.0.4
    >> >> >
    >> >> >--
    >> >> >To unsubscribe from this list: send the line "unsubscribe linux-pci" in
    >> >> >the body of a message to majordomo@vger.kernel.org
    >> >> >More majordomo info at http://vger.kernel.org/majordomo-info.html
    >> >>
    >> >> --
    >> >> Richard Yang
    >> >> Help you, Help me
    >> >>
    >> >> --
    >> >> To unsubscribe from this list: send the line "unsubscribe linux-pci" in
    >> >> the body of a message to majordomo@vger.kernel.org
    >> >> More majordomo info at http://vger.kernel.org/majordomo-info.html
    >> >>
    >> >
    >>
    >> --
    >> Richard Yang
    >> Help you, Help me
    >>
    >>
    >
    >--
    >====================
    >| I would like to |
    >| fix the world, |
    >| but they're not |
    >| giving me the |
    > \ source code! /
    > ---------------
    > ¯\_(ツ)_/¯

    --
    Richard Yang
    Help you, Help me

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