Re: [PATCH v9 02/12] PCI: OF: Parse and map the IRQ when adding the PCI device.

[Wei Yang]

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@xxxxxxxxxx>
>> >Cc: Grant Likely <grant.likely@xxxxxxxxxx>
>> >Cc: Rob Herring <robh+dt@xxxxxxxxxx>
>> >Signed-off-by: Liviu Dudau <Liviu.Dudau@xxxxxxx>
>> >---
>> > 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.

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
    2. have other way to fix it up,  otherwise how it works now?
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.

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
>> >
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>> -- 
>> Richard Yang
>> Help you, Help me
>> 
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>
>-- 
>====================
>| I would like to |
>| fix the world,  |
>| but they're not |
>| giving me the   |
> \ source code!  /
>  ---------------
>    Â\_(ã)_/Â

-- 
Richard Yang
Help you, Help me

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