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Message-ID: <4942906.jTIhNoktzo@vostro.rjw.lan>
Date: Fri, 26 Apr 2013 12:58:12 +0200
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: Yinghai Lu <yinghai@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
Jiang Liu <jiang.liu@...wei.com>,
Gavin Guo <tuffkidtt@...il.com>, linux-pci@...r.kernel.org,
linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH -v3] PCI, ACPI, hotplug: Fix BUS_CHECK event handle on root bridge
On Thursday, April 25, 2013 06:46:38 PM Yinghai Lu wrote:
> Gavin found that acpiphp does not handle hotplug anymore even after
> now we have acpiphp built-in preparing for v3.10.
>
> Bjorn analyzed bootlog, he found that
> acpiphp: ACPI Hot Plug PCI Controller Driver version: 0.5
> ACPI: PCI Root Bridge [PCI0] (domain 0000 [bus 00-3e])
> \_SB_.PCI0:_OSC invalid UUID
> acpiphp: Slot [1] registered
> acpiphp: Slot [1-1] registered
> acpi root: \_SB_.PCI0 notify handler is installed
> _handle_hotplug_event_root: Bus check notify on \_SB_.PCI0
> _handle_hotplug_event_root: Bus check notify on \_SB_.PCI0
> And that means:
> So we should be using acpiphp, which you do have built in statically,
> and it found a couple slots. And we did get two bus check notifies on
> \_SB_.PCI0, so we *should* be re-enumerating PCI bus 0000:00. But it
> looks like we're handling this as a host bridge hotplug event instead
> of a PCI device hotplug. My guess is that
> handle_root_bridge_insertion() does nothing because the PCI0 ACPI
> device already exists, though I would expect to see the "acpi device
> exists..." in your dmesg log if this were the case.
>
> Also according to Rafael and Bjorn, it is perfect fine that we
> should enumerate bus by sending event to root bridge after hotadd
> device to slots under that root bridge or children bridges.
>
> It turns out that it is regression caused by
> | commit 668192b678201d2fff27c6cc76bb003c1ec4a52a
> | Author: Yinghai Lu <yinghai@...nel.org>
> | Date: Mon Jan 21 13:20:48 2013 -0800
> |
> | PCI: acpiphp: Move host bridge hotplug to pci_root.c
>
> We should check slots when BUS_CHECK is sent to root bridge acpi handle.
>
> Restore the old behavoir by calling acpi_check_bridge and check_sub_bridge
> in acpiphp.
>
> Jiang Liu acctually have simimar patch but it forgets calling
> acpi_check_bridge() for system that have slots on root bus directly.
> That is still valid, as in QEMU we still have that slots on bus 0 at
> least. But my first version patch wrongly check if root bridge exists
> before check_sub_bridge for children bridges.
>
> -v2: Don't check bridge for acpi_walk_namespace with check_sub_bridges.
> also put back bridge reference.
> -v3: More changelog and etc.
>
> Reported-by: Gavin Guo <tuffkidtt@...il.com>
> Tested-by: Gavin Guo <tuffkidtt@...il.com>
> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> ---
> drivers/acpi/pci_root.c | 2 ++
> drivers/pci/hotplug/acpiphp_glue.c | 14 ++++++++++++++
> include/linux/pci-acpi.h | 2 ++
> 3 files changed, 18 insertions(+)
>
> Index: linux-2.6/drivers/acpi/pci_root.c
> ===================================================================
> --- linux-2.6.orig/drivers/acpi/pci_root.c
> +++ linux-2.6/drivers/acpi/pci_root.c
> @@ -643,6 +643,8 @@ static void _handle_hotplug_event_root(s
> (char *)buffer.pointer);
> if (!root)
> handle_root_bridge_insertion(handle);
> + else
> + acpiphp_check_host_bridge(handle);
>
> break;
>
> Index: linux-2.6/drivers/pci/hotplug/acpiphp_glue.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/hotplug/acpiphp_glue.c
> +++ linux-2.6/drivers/pci/hotplug/acpiphp_glue.c
> @@ -950,6 +950,20 @@ check_sub_bridges(acpi_handle handle, u3
> return AE_OK ;
> }
>
> +void acpiphp_check_host_bridge(acpi_handle handle)
> +{
> + struct acpiphp_bridge *bridge;
> +
> + bridge = acpiphp_handle_to_bridge(handle);
> + if (bridge) {
> + acpiphp_check_bridge(bridge);
> + put_bridge(bridge);
> + }
> +
> + acpi_walk_namespace(ACPI_TYPE_DEVICE, handle,
> + ACPI_UINT32_MAX, check_sub_bridges, NULL, NULL, NULL);
> +}
> +
> static void _handle_hotplug_event_bridge(struct work_struct *work)
> {
> struct acpiphp_bridge *bridge;
> Index: linux-2.6/include/linux/pci-acpi.h
> ===================================================================
> --- linux-2.6.orig/include/linux/pci-acpi.h
> +++ linux-2.6/include/linux/pci-acpi.h
> @@ -60,11 +60,13 @@ static inline void acpi_pci_slot_remove(
> void acpiphp_init(void);
> void acpiphp_enumerate_slots(struct pci_bus *bus, acpi_handle handle);
> void acpiphp_remove_slots(struct pci_bus *bus);
> +void acpiphp_check_host_bridge(acpi_handle handle);
> #else
> static inline void acpiphp_init(void) { }
> static inline void acpiphp_enumerate_slots(struct pci_bus *bus,
> acpi_handle handle) { }
> static inline void acpiphp_remove_slots(struct pci_bus *bus) { }
> +static inline void acpiphp_check_host_bridge(acpi_handle handle) { }
> #endif
>
> #else /* CONFIG_ACPI */
--
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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