linux-kernel - Re: [PATCH 0/4] ACPI / bind: Simplify child devices lookup

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Message-ID: <6140633.otq91cJcVd@vostro.rjw.lan>
Date:	Wed, 27 Nov 2013 02:32:53 +0100
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Toshi Kani <toshi.kani@...com>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Aaron Lu <aaron.lu@...el.com>
Subject: Re: [PATCH 0/4] ACPI / bind: Simplify child devices lookup

On Tuesday, November 26, 2013 06:11:57 PM Toshi Kani wrote:
> On Wed, 2013-11-27 at 02:02 +0100, Rafael J. Wysocki wrote:
> > On Tuesday, November 26, 2013 05:33:28 PM Toshi Kani wrote:
> > > On Wed, 2013-11-27 at 01:27 +0100, Rafael J. Wysocki wrote:
> > > > On Tuesday, November 26, 2013 05:00:42 PM Toshi Kani wrote:
> > > > > On Mon, 2013-11-25 at 01:09 +0100, Rafael J. Wysocki wrote:
> > > > > > Hi,
> > > > > > 
> > > > > > The following series of four patches (on top of current linux-pm.git/bleeding-edge)
> > > > > > rework child device lookup in drivers/acpi/glue.c and related things:
> > > > > > 
> > > > > > [1/4] ACPI / bind: Simplify child device lookup
> > > > > > [2/4] PCI/ ACPI: Use acpi_find_child_device() for child device lookup
> > > > > > [3/4] ACPI / bind: Redefine acpi_get_child()
> > > > > > [4/4] ACPI / bind: Redefine acpi_preset_companion()
> > > > > 
> > > > > This patchset caused the attached panic during boot on a system.
> > > > > acpi_pci_find_device() called acpi_find_child_device() with
> > > > > ACPI_COMPANION(dev->parent) being a NULL pointer when scanning bus 0xf.
> > > > > 
> > > > > This bus 0xf seems to be a chipset internal bus, which is not intended
> > > > > for the OS to use.  Therefore, ACPI does not list its PCI bridge device.
> > > > > 
> > > > > # lspci -tv
> > > > >    :
> > > > >  +-[0000:0f]-+-08.0  Intel Corporation Ivytown QPI Link 0
> > > > >  |           +-08.2  Intel Corporation Ivytown QPI Link 0
> > > > >    :
> > > > > 
> > > > > However, pcibios_fixup_peer_bridges(), called from pci_subsys_init(),
> > > > > finds this bus as it scans all the buses from 0 to pcibios_last_bus.
> > > > > Hence, this dev->parent does not have an associated ACPI device object. 
> > > > 
> > > > Thanks for the report!
> > > > 
> > > > I've dropped the patches from bleeding-edge for now.
> > > > 
> > > > Does "[1/4] ACPI / bind: Simplify child device lookup" alone work on that
> > > > system?
> > > 
> > > Yes, the system boots fine with 1/4 alone.
> > 
> > Thanks!
> > 
> > Can you please check if the following modified [2/4] also works on top of it?
> 
> Yes, it works fine.
> 
> Thanks for the quick fix!

No problem. :-)

[3/4] and [4/4] on top of this one should work too.

Thanks,
Rafael

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