powerpc/pci: Use of_irq_parse_and_map_pci() helper

Hi Rob,

I can no longer boot my old Mac Mini G4 using a custom config. After a
tedious bisect it appears that (*). Since Mac Mini does not provide
any serial port I cannot provide a kernel message dump (wish there was
some kind of null modem serial cable). All I can see is some crazy
stuff going on with ATA DMA/66 & DMA/100.

Is there anything suspicious in this commit which may prevent this
machine to boot ?

Thanks much,

(*)
$ git bisect good
59f47eff03a08cd2d91310f1c15a5343fa0071e5 is the first bad commit
commit 59f47eff03a08cd2d91310f1c15a5343fa0071e5
Author: Rob Herring [off-list ref]
Date:   Thu Jan 4 15:12:14 2018 -0600

    powerpc/pci: Use of_irq_parse_and_map_pci() helper

    Instead of calling both of_irq_parse_pci() and irq_create_of_mapping(),
    call of_irq_parse_and_map_pci(), which does the same thing. This will allow
    making of_irq_parse_pci() a private, static function.

    This changes the logic slightly in that the fallback path will also be
    taken if irq_create_of_mapping() fails internally.

    Signed-off-by: Rob Herring [off-list ref]
    [bhelgaas: fold in virq init from Stephen Rothwell [off-list ref]]
    Signed-off-by: Bjorn Helgaas [off-list ref]
    Cc: Benjamin Herrenschmidt [off-list ref]
    Cc: Paul Mackerras [off-list ref]
    Cc: Michael Ellerman [off-list ref]

:040000 040000 b979406deb8957af240d659be1e76ed75fa43288
ec3c127fe30428955e2ad1d716c9be2adbd2623d M arch

On Fri, Feb 9, 2018 at 4:01 PM, Mathieu Malaterre [off-list ref] wrote:

Hi Rob,

I can no longer boot my old Mac Mini G4 using a custom config. After a
tedious bisect it appears that (*). Since Mac Mini does not provide
any serial port I cannot provide a kernel message dump (wish there was
some kind of null modem serial cable). All I can see is some crazy
stuff going on with ATA DMA/66 & DMA/100.

Is there anything suspicious in this commit which may prevent this
machine to boot ?

Yes, it's broken. You need this patch[1]. Sorry for the breakage.

Rob

[1] https://patchwork.kernel.org/patch/10208267/