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Date: Mon, 17 Dec 2012 13:13:53 +0100 From: "Rafael J. Wysocki" <rjw@...k.pl> To: Yinghai Lu <yinghai@...nel.org> Cc: ACPI Devel Maling List <linux-acpi@...r.kernel.org>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, LKML <linux-kernel@...r.kernel.org>, Bjorn Helgaas <bhelgaas@...gle.com>, Benjamin Herrenschmidt <benh@...nel.crashing.org>, David Miller <davem@...emloft.net>, tony.luck@...el.com, "H. Peter Anvin" <hpa@...or.com>, Jiang Liu <liuj97@...il.com> Subject: Re: [PATCH] ACPI / PCI: Set root bridge ACPI handle in advance On Monday, December 17, 2012 12:09:46 AM Yinghai Lu wrote: > On Sun, Dec 16, 2012 at 11:51 PM, Rafael J. Wysocki <rjw@...k.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@...k.pl> wrote: > >> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.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@...el.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 Ah, it's been added rather than removed. :-) OK, will address. > >> 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; > Good point, I didn't think about that. Thanks! > >> > > >> > 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. Thanks for the review! Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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