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Date: Sun, 20 Jan 2013 18:32:59 -0800
From: Yinghai Lu <yinghai@...nel.org>
To: "Rafael J. Wysocki" <rjw@...k.pl>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, Len Brown <lenb@...nel.org>,
Taku Izumi <izumi.taku@...fujitsu.com>,
Jiang Liu <jiang.liu@...wei.com>, linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org
Subject: Re: [PATCH v9 07/11] PCI, acpiphp: Move and enhance hotplug support
of pci host bridge
On Sun, Jan 20, 2013 at 2:55 PM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> On Thursday, January 17, 2013 11:53:18 PM Yinghai Lu wrote:
>> We have partial hot-add support in acpiphp driver, and it is confusing.
>>
>> Move host bridge hot-add support to pci_root.c, and keep acpiphp simple,
>> also add hot-remove support in pci_root.c.
>>
>> How to test it: if sci_emu patch is applied,
>>
>> Find out root bus number to acpi root name mapping from dmesg or /sys
>>
>> echo "\_SB.PCIB 3" > /sys/kernel/debug/acpi/sci_notify
>> to remove root bus
>>
>> echo "\_SB.PCIB 1" > /sys/kernel/debug/acpi/sci_notify
>> to add back root bus
>>
>> -v2: put back pci_root_hp change in one patch
>> -v3: add pcibios_resource_survey_bus() calling
>> -v4: remove not needed code with remove_bridge
>> -v5: put back support for acpiphp support for slots just on root bus.
>> -v6: change some functions to *_p2p_* to make it more clean.
>> -v7: split hot_added change out.
>> -v8: Move to pci_root.c instead of adding another file requested by Bjorn.
>> -v9: Fold three following patches into this one for easy review:
>> a: Add missing hot_remove support for root device.
>> b: Tang Chen noticed that hotplug through container will not update
>> acpi_root_bridge list. After closely checking, we don't need
>> that for struct for tracking and could use acpi_pci_root directly.
>> c: Tang Chen found handle_root_bridge_removal is very similiar to
>> acpi_bus_hot_remove_device(). Change to handle_root_bridge_removal
>> to use acpi_bus_hot_remove_device.
>>
>> Signed-off-by: Yinghai Lu <yinghai@...nel.org>
>> ---
>> drivers/acpi/pci_root.c | 139 ++++++++++++++++++++++++++++++++++++
>> drivers/pci/hotplug/acpiphp_glue.c | 59 ++++-----------
>> 2 files changed, 154 insertions(+), 44 deletions(-)
>>
>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c
>> index bf5108a..3ce5d80 100644
>> --- a/drivers/acpi/pci_root.c
>> +++ b/drivers/acpi/pci_root.c
>> @@ -655,3 +655,142 @@ int __init acpi_pci_root_init(void)
>>
>> return 0;
>> }
>> +
>> +/* Support root bridge hotplug */
>> +
>> +static void handle_root_bridge_insertion(acpi_handle handle)
>> +{
>> + struct acpi_device *device, *pdevice;
>> + acpi_handle phandle;
>> + int ret_val;
>> +
>> + acpi_get_parent(handle, &phandle);
>> + if (acpi_bus_get_device(phandle, &pdevice)) {
>> + printk(KERN_DEBUG "no parent device, assuming NULL\n");
>> + pdevice = NULL;
>> + }
>> + if (!acpi_bus_get_device(handle, &device)) {
>> + /* check if pci root_bus is removed */
>> + struct acpi_pci_root *root = acpi_driver_data(device);
>> + if (pci_find_bus(root->segment, root->secondary.start))
>> + return;
>> +
>> + printk(KERN_DEBUG "bus exists... trim\n");
>> + /* this shouldn't be in here, so remove
>> + * the bus then re-add it...
>> + */
>> + ret_val = acpi_bus_trim(device);
>
> You said that this followed acpiphp, but the purpose of the trimming in there
> seems to be to handle surprise removal and re-insertion, which I'm not sure is
> OK with something like a host bridge.
ok, will just bail out if it is there.
>
> The drawback is that if we have a spurious ACPI_NOTIFY_BUS_CHECK or
> ACPI_NOTIFY_DEVICE_CHECK, we'll be trying to remove the whole bus here in
> response. That doesn't sound quite right.
>
>> + printk(KERN_DEBUG "acpi_bus_trim return %x\n", ret_val);
>> + }
>> + if (acpi_bus_add(handle))
>> + printk(KERN_ERR "cannot add bridge to acpi list\n");
>> +}
>> +
>> +static void handle_root_bridge_removal(struct acpi_device *device)
>> +{
>> + struct acpi_eject_event *ej_event;
>> +
>> + ej_event = kmalloc(sizeof(*ej_event), GFP_KERNEL);
>> + if (!ej_event)
>
> Shouldn't we do acpi_evaluate_hotplug_ost() here?
ok. will add
/* Inform firmware the hot-remove operation has error */
(void) acpi_evaluate_hotplug_ost(device->handle,
ACPI_NOTIFY_EJECT_REQUEST,
ACPI_OST_SC_NON_SPECIFIC_FAILURE,
NULL);
before return.
>
>> + return;
>> +
>> + ej_event->device = device;
>> + ej_event->event = ACPI_NOTIFY_EJECT_REQUEST;
>> +
>> + acpi_bus_hot_remove_device(ej_event);
>> +}
>> +
>> +static void _handle_hotplug_event_root(struct work_struct *work)
>> +{
>> + struct acpi_pci_root *root;
>> + char objname[64];
>> + struct acpi_buffer buffer = { .length = sizeof(objname),
>> + .pointer = objname };
>> + struct acpi_hp_work *hp_work;
>> + acpi_handle handle;
>> + u32 type;
>> +
>> + hp_work = container_of(work, struct acpi_hp_work, work);
>> + handle = hp_work->handle;
>> + type = hp_work->type;
>> +
>> + root = acpi_pci_find_root(handle);
>> +
>> + acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
>
> Is the path guaranteed not to be longer than 64 characters?
good. will use
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER };
instead.
>
>> +
>> + switch (type) {
>> + case ACPI_NOTIFY_BUS_CHECK:
>> + /* bus enumerate */
>> + printk(KERN_DEBUG "%s: Bus check notify on %s\n", __func__,
>> + objname);
>
> pr_debug() would be nicer (and analogously below).
maybe we can change that later after it gets stable a bit.
>
>> + if (!root)
>> + handle_root_bridge_insertion(handle);
>> +
>> + break;
>> +
>> + case ACPI_NOTIFY_DEVICE_CHECK:
>> + /* device check */
>> + printk(KERN_DEBUG "%s: Device check notify on %s\n", __func__,
>> + objname);
>> + if (!root)
>> + handle_root_bridge_insertion(handle);
>> + break;
>> +
>> + case ACPI_NOTIFY_EJECT_REQUEST:
>> + /* request device eject */
>> + printk(KERN_DEBUG "%s: Device eject notify on %s\n", __func__,
>> + objname);
>> + if (root)
>> + handle_root_bridge_removal(root->device);
>> + break;
>> + default:
>> + printk(KERN_WARNING "notify_handler: unknown event type 0x%x for %s\n",
>> + type, objname);
>> + break;
>> + }
>> +
>> + kfree(hp_work); /* allocated in handle_hotplug_event_bridge */
>> +}
>> +
>> +static void handle_hotplug_event_root(acpi_handle handle, u32 type,
>> + void *context)
>> +{
>> + alloc_acpi_hp_work(handle, type, context,
>> + _handle_hotplug_event_root);
>> +}
>> +
>> +static acpi_status __init
>> +find_root_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
>> +{
>> + char objname[64];
>> + struct acpi_buffer buffer = { .length = sizeof(objname),
>> + .pointer = objname };
>> + int *count = (int *)context;
>> +
>> + if (!acpi_is_root_bridge(handle))
>> + return AE_OK;
>> +
>> + (*count)++;
>> +
>> + acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
>> +
>> + acpi_install_notify_handler(handle, ACPI_SYSTEM_NOTIFY,
>> + handle_hotplug_event_root, NULL);
>> + printk(KERN_DEBUG "acpi root: %s notify handler installed\n", objname);
>> +
>> + return AE_OK;
>> +}
>> +
>> +static int __init acpi_pci_root_hp_init(void)
>> +{
>> + int num = 0;
>> +
>> + acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
>> + ACPI_UINT32_MAX, find_root_bridges, NULL, &num, NULL);
>> +
>> + printk(KERN_DEBUG "Found %d acpi root devices\n", num);
>> +
>> + return 0;
>> +}
>> +
>> +subsys_initcall(acpi_pci_root_hp_init);
>
> Why do we need a separate initcall here? Is it not enough to call
> acpi_pci_root_hp_init() from acpi_init() or acpi_scan_init(), or
> acpi_pci_root_init() even?
ok, will give it a try.
Thanks
Yinghai
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