lkml.org 
[lkml]   [2012]   [Dec]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH] ACPI / PCI: Set root bridge ACPI handle in advance
From
On Sun, Dec 16, 2012 at 11:51 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
> On Sunday, December 16, 2012 09:27:49 PM Yinghai Lu wrote:
>> On Sun, Dec 16, 2012 at 2:25 PM, Rafael J. Wysocki <rjw@sisk.pl> wrote:
>> > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> >
>> > The ACPI handles of PCI root bridges need to be known to
>> > acpi_bind_one(), so that it can create the appropriate
>> > "firmware_node" and "physical_node" files for them, but currently
>> > the way it gets to know those handles is not exactly straightforward
>> > (to put it lightly).
>> >
>> > This is how it works, roughly:
>> >
>> > 1. acpi_bus_scan() finds the handle of a PCI root bridge,
>> > creates a struct acpi_device object for it and passes that
>> > object to acpi_pci_root_add().
>> >
>> > 2. acpi_pci_root_add() creates a struct acpi_pci_root object,
>> > populates its "device" field with its argument's address
>> > (device->handle is the ACPI handle found in step 1).
>> >
>> > 3. The struct acpi_pci_root object created in step 2 is passed
>> > to pci_acpi_scan_root() and used to get resources that are
>> > passed to pci_create_root_bus().
>> >
>> > 4. pci_create_root_bus() creates a struct pci_host_bridge object
>> > and passes its "dev" member to device_register().
>> >
>> > 5. platform_notify(), which for systems with ACPI is set to
>> > acpi_platform_notify(), is called.
>> >
>> > So far, so good. Now it starts to be "interesting".
>> >
>> > 6. acpi_find_bridge_device() is used to find the ACPI handle of
>> > the given device (which is the PCI root bridge) and executes
>> > acpi_pci_find_root_bridge(), among other things, for the
>> > given device object.
>> >
>> > 7. acpi_pci_find_root_bridge() uses the name (sic!) of the given
>> > device object to extract the segment and bus numbers of the PCI
>> > root bridge and passes them to acpi_get_pci_rootbridge_handle().
>> >
>> > 8. acpi_get_pci_rootbridge_handle() browses the list of ACPI PCI
>> > root bridges and finds the one that matches the given segment
>> > and bus numbers. Its handle is then used to initialize the
>> > ACPI handle of the PCI root bridge's device object by
>> > acpi_bind_one(). However, this is *exactly* the ACPI handle we
>> > started with in step 1.
>> >
>> > Needless to say, this is quite embarassing, but it may be avoided
>> > thanks to commit f3fd0c8 (ACPI: Allow ACPI handles of devices to be
>> > initialized in advance), which makes it possible to initialize the
>> > ACPI handle of a device before passing it to device_register().
>> > Namely, if pci_acpi_scan_root() could easily pass the root bridge's
>> > ACPI handle to pci_create_root_bus(), the latter could set the ACPI
>> > handle in its struct pci_host_bridge object's "dev" member before
>> > passing it to device_register() and steps 6-8 above wouldn't be
>> > necessary any more.
>> >
>> > To make that happen I decided to repurpose the 4th argument of
>> > pci_create_root_bus(), because that allowed me to avoid defining
>> > additional callbacks or similar things and didn't seem to impact
>> > architectures without ACPI substantially.
>> >
>> > Only x86 and ia64 are affected directly, there should be no
>> > functional changes resulting from this on other architectures.
>>
>> that is good one to avoid that find_root_bridge...
>>
>> >
>> > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> > ---
>> >
>> > Should apply to the current Linus' tree, boots correctly on x86(-64).
>
>> >
>> > ---
>> > arch/ia64/pci/pci.c | 5 ++++-
>> > arch/powerpc/kernel/pci-common.c | 3 ++-
>> > arch/sparc/kernel/pci.c | 3 ++-
>> > arch/x86/pci/acpi.c | 5 ++++-
>> > drivers/acpi/pci_root.c | 18 ------------------
>> > drivers/pci/pci-acpi.c | 19 -------------------
>> > drivers/pci/probe.c | 16 +++++++++++-----
>> > include/acpi/acpi_bus.h | 1 -
>> > include/linux/pci.h | 9 ++++++++-
>> > 9 files changed, 31 insertions(+), 48 deletions(-)
>>
>> you need to update other arch for pci_create_root_bus
>>
>> arch/powerpc/kernel/pci-common.c: bus =
>> pci_create_root_bus(hose->parent, hose->first_busno,
>
> I thought I addressed this one, didn't I?
>
>> arch/s390/pci/pci.c: zdev->bus = pci_create_root_bus(NULL,
>> ZPCI_BUS_NR, &pci_root_ops,
>
> This one appears to have been removed. There's no pci_create_root_bus()
> in all arch/s390, as far as I can say.

at least it is there on linus tree today.

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=blob;f=arch/s390/pci/pci.c;h=7ed38e5e3028689543c8c6356ef49b3a45546cd6;hb=HEAD

line 890

>
>> arch/sparc/kernel/pci.c: bus = pci_create_root_bus(parent,
>> pbm->pci_first_busno, pbm->pci_ops,
>
> I modified this one too, is that not sufficient?
>
>> drivers/parisc/dino.c: dino_dev->hba.hba_bus = bus =
>> pci_create_root_bus(&dev->dev,
>> drivers/parisc/lba_pci.c: pci_create_root_bus(&dev->dev,
>> lba_dev->hba.bus_num.start,
>
> These two pass NULL as the 4th argument to pci_create_root_bus() and don't
> need to be updated, AFAICS.

then how could
- b->sysdata = sysdata;
+ b->sysdata = sys_info->sysdata;

be survived ? need to change to

+ b->sysdata = sys_info?sys_info->sysdata : NULL;

>
>> >
>> > Index: linux/arch/x86/pci/acpi.c
>> > ===================================================================
>> > --- linux.orig/arch/x86/pci/acpi.c
>> > +++ linux/arch/x86/pci/acpi.c
>> > @@ -450,6 +450,7 @@ struct pci_bus * __devinit pci_acpi_scan
>> > LIST_HEAD(resources);
>> > struct pci_bus *bus = NULL;
>> > struct pci_sysdata *sd;
>> > + struct pci_root_sys_info si;
>> > int node;
>> > #ifdef CONFIG_ACPI_NUMA
>> > int pxm;
>> > @@ -486,6 +487,8 @@ struct pci_bus * __devinit pci_acpi_scan
>> > sd = &info->sd;
>> > sd->domain = domain;
>> > sd->node = node;
>> > + si.acpi_node.handle = device->handle;
>> > + si.sysdata = sd;
>>
>> maybe you can try to have si.acpi_handle directly ?
>
> I did it this way for handle to be compiled out when CONFIG_ACPI is not set
> (struct acpi_dev_node is an empty structure in that case).

ok.


\
 
 \ /
  Last update: 2012-12-17 10:01    [W:2.017 / U:0.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site