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Date: Thu, 31 Jan 2013 23:37:00 +0800
From: Jiang Liu <liuj97@...il.com>
To: Yinghai Lu <yinghai@...nel.org>
CC: Bjorn Helgaas <bhelgaas@...gle.com>,
"Rafael J . Wysocki" <rjw@...k.pl>,
Jiang Liu <jiang.liu@...wei.com>,
Yijing Wang <wangyijing@...wei.com>,
linux-kernel@...r.kernel.org, linux-pci@...r.kernel.org
Subject: Re: [PATCH 2/2] acpiphp: remove dead code for PCI host bridge hotplug
On 01/31/2013 01:27 AM, Yinghai Lu wrote:
> On Wed, Jan 30, 2013 at 8:10 AM, Jiang Liu <liuj97@...il.com> wrote:
>> From: Jiang Liu <jiang.liu@...wei.com>
>>
>> Commit 668192b678201d2fff27c "PCI: acpiphp: Move host bridge hotplug
>> to pci_root.c" has moved PCI host bridge hotplug logic from acpiphp
>> to pci_root, but there is still PCI host bridge hotplug related
>> dead code left in acpiphp. So remove those dead code.
>>
>> Now companion ACPI devices are always created before corresponding
>> PCI devices. And the ACPI event handle_hotplug_event_bridge() will be
>> installed only if it has associated PCI device. So remove dead code to
>> handle bridge hot-adding in function handle_hotplug_event_bridge().
>>
>> Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
>> ---
>> drivers/pci/hotplug/acpiphp.h | 13 +---
>> drivers/pci/hotplug/acpiphp_glue.c | 124 ++++--------------------------------
>> 2 files changed, 14 insertions(+), 123 deletions(-)
>>
>> diff --git a/drivers/pci/hotplug/acpiphp.h b/drivers/pci/hotplug/acpiphp.h
>> index b3ead7a..b70ac00 100644
>> --- a/drivers/pci/hotplug/acpiphp.h
>> +++ b/drivers/pci/hotplug/acpiphp.h
>> @@ -79,7 +79,6 @@ struct acpiphp_bridge {
>> /* Ejectable PCI-to-PCI bridge (PCI bridge and PCI function) */
>> struct acpiphp_func *func;
>>
>> - int type;
>> int nr_slots;
>>
>> u32 flags;
>> @@ -146,10 +145,6 @@ struct acpiphp_attention_info
>> /* PCI bus bridge HID */
>> #define ACPI_PCI_HOST_HID "PNP0A03"
>>
>> -/* PCI BRIDGE type */
>> -#define BRIDGE_TYPE_HOST 0
>> -#define BRIDGE_TYPE_P2P 1
>> -
>> /* ACPI _STA method value (ignore bit 4; battery present) */
>> #define ACPI_STA_PRESENT (0x00000001)
>> #define ACPI_STA_ENABLED (0x00000002)
>> @@ -158,13 +153,7 @@ struct acpiphp_attention_info
>> #define ACPI_STA_ALL (0x0000000f)
>>
>> /* bridge flags */
>> -#define BRIDGE_HAS_STA (0x00000001)
>> -#define BRIDGE_HAS_EJ0 (0x00000002)
>> -#define BRIDGE_HAS_HPP (0x00000004)
>> -#define BRIDGE_HAS_PS0 (0x00000010)
>> -#define BRIDGE_HAS_PS1 (0x00000020)
>> -#define BRIDGE_HAS_PS2 (0x00000040)
>> -#define BRIDGE_HAS_PS3 (0x00000080)
>> +#define BRIDGE_HAS_EJ0 (0x00000001)
>>
>> /* slot flags */
>>
>> diff --git a/drivers/pci/hotplug/acpiphp_glue.c b/drivers/pci/hotplug/acpiphp_glue.c
>> index acb7af2..4681d2c 100644
>> --- a/drivers/pci/hotplug/acpiphp_glue.c
>> +++ b/drivers/pci/hotplug/acpiphp_glue.c
>> @@ -325,8 +325,8 @@ static void init_bridge_misc(struct acpiphp_bridge *bridge)
>> return;
>> }
>>
>> - /* install notify handler */
>> - if (bridge->type != BRIDGE_TYPE_HOST) {
>> + /* install notify handler for P2P bridges */
>> + if (!pci_is_root_bus(bridge->pci_bus)) {
>> if ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func) {
>> status = acpi_remove_notify_handler(bridge->func->handle,
>> ACPI_SYSTEM_NOTIFY,
>> @@ -369,27 +369,12 @@ static struct acpiphp_func *acpiphp_bridge_handle_to_function(acpi_handle handle
>> static inline void config_p2p_bridge_flags(struct acpiphp_bridge *bridge)
>> {
>> acpi_handle dummy_handle;
>> + struct acpiphp_func *func;
>>
>> if (ACPI_SUCCESS(acpi_get_handle(bridge->handle,
>> - "_STA", &dummy_handle)))
>> - bridge->flags |= BRIDGE_HAS_STA;
>> -
>> - if (ACPI_SUCCESS(acpi_get_handle(bridge->handle,
>> - "_EJ0", &dummy_handle)))
>> + "_EJ0", &dummy_handle))) {
>> bridge->flags |= BRIDGE_HAS_EJ0;
>>
>> - if (ACPI_SUCCESS(acpi_get_handle(bridge->handle,
>> - "_PS0", &dummy_handle)))
>> - bridge->flags |= BRIDGE_HAS_PS0;
>> -
>> - if (ACPI_SUCCESS(acpi_get_handle(bridge->handle,
>> - "_PS3", &dummy_handle)))
>> - bridge->flags |= BRIDGE_HAS_PS3;
>> -
>> - /* is this ejectable p2p bridge? */
>> - if (bridge->flags & BRIDGE_HAS_EJ0) {
>> - struct acpiphp_func *func;
>> -
>> dbg("found ejectable p2p bridge\n");
>>
>> /* make link between PCI bridge and PCI function */
>> @@ -412,7 +397,6 @@ static void add_host_bridge(struct acpi_pci_root *root)
>> if (bridge == NULL)
>> return;
>>
>> - bridge->type = BRIDGE_TYPE_HOST;
>> bridge->handle = handle;
>>
>> bridge->pci_bus = root->bus;
>> @@ -432,7 +416,6 @@ static void add_p2p_bridge(acpi_handle *handle)
>> return;
>> }
>>
>> - bridge->type = BRIDGE_TYPE_P2P;
>> bridge->handle = handle;
>> config_p2p_bridge_flags(bridge);
>>
>> @@ -543,7 +526,7 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
>> acpi_status status;
>> acpi_handle handle = bridge->handle;
>>
>> - if (bridge->type != BRIDGE_TYPE_HOST) {
>> + if (!pci_is_root_bus(bridge->pci_bus)) {
>> status = acpi_remove_notify_handler(handle,
>> ACPI_SYSTEM_NOTIFY,
>> handle_hotplug_event_bridge);
>> @@ -551,8 +534,7 @@ static void cleanup_bridge(struct acpiphp_bridge *bridge)
>> err("failed to remove notify handler\n");
>> }
>>
>> - if ((bridge->type != BRIDGE_TYPE_HOST) &&
>> - ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func)) {
>> + if ((bridge->flags & BRIDGE_HAS_EJ0) && bridge->func) {
>> status = acpi_install_notify_handler(bridge->func->handle,
>> ACPI_SYSTEM_NOTIFY,
>> handle_hotplug_event_func,
>> @@ -1122,64 +1104,11 @@ static void acpiphp_sanitize_bus(struct pci_bus *bus)
>> }
>> }
>>
>> -/* Program resources in newly inserted bridge */
>> -static int acpiphp_configure_p2p_bridge(acpi_handle handle)
>> -{
>> - struct pci_dev *pdev = acpi_get_pci_dev(handle);
>> - struct pci_bus *bus = pdev->subordinate;
>> -
>> - pci_dev_put(pdev);
>> -
>> - pci_bus_size_bridges(bus);
>> - pci_bus_assign_resources(bus);
>> - acpiphp_sanitize_bus(bus);
>> - acpiphp_set_hpp_values(bus);
>> - pci_enable_bridges(bus);
>> - return 0;
>> -}
>> -
>> -static void handle_p2p_bridge_insertion(acpi_handle handle, u32 type)
>> -{
>> - struct acpi_device *device;
>> -
>> - if ((type != ACPI_NOTIFY_BUS_CHECK) &&
>> - (type != ACPI_NOTIFY_DEVICE_CHECK)) {
>> - err("unexpected notification type %d\n", type);
>> - return;
>> - }
>> -
>> - if (acpi_bus_scan(handle)) {
>> - err("cannot add bridge to acpi list\n");
>> - return;
>> - }
>> - if (acpi_bus_get_device(handle, &device)) {
>> - err("ACPI device object missing\n");
>> - return;
>> - }
>> - if (!acpiphp_configure_p2p_bridge(handle))
>> - add_p2p_bridge(handle);
>> - else
>> - err("cannot configure and start bridge\n");
>> -
>> -}
>> -
>> /*
>> * ACPI event handlers
>> */
>>
>> static acpi_status
>> -count_sub_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
>> -{
>> - int *count = (int *)context;
>> - struct acpiphp_bridge *bridge;
>> -
>> - bridge = acpiphp_handle_to_bridge(handle);
>> - if (bridge)
>> - (*count)++;
>> - return AE_OK ;
>> -}
>> -
>> -static acpi_status
>> check_sub_bridges(acpi_handle handle, u32 lvl, void *context, void **rv)
>> {
>> struct acpiphp_bridge *bridge;
>> @@ -1203,8 +1132,6 @@ static void _handle_hotplug_event_bridge(struct work_struct *work)
>> char objname[64];
>> struct acpi_buffer buffer = { .length = sizeof(objname),
>> .pointer = objname };
>> - struct acpi_device *device;
>> - int num_sub_bridges = 0;
>> struct acpi_hp_work *hp_work;
>> acpi_handle handle;
>> u32 type;
>> @@ -1212,23 +1139,7 @@ static void _handle_hotplug_event_bridge(struct work_struct *work)
>> hp_work = container_of(work, struct acpi_hp_work, work);
>> handle = hp_work->handle;
>> type = hp_work->type;
>> -
>> - if (acpi_bus_get_device(handle, &device)) {
>> - /* This bridge must have just been physically inserted */
>> - handle_p2p_bridge_insertion(handle, type);
>> - goto out;
>> - }
>
> According to my understanding, for acpiphp we still need to support:
>
> one slot is on root bus 0, and will take p2p bridge directly.
Hi Yinghai,
I think the acpiphp driver still supports PCI hotplug slots directly attached
to PCI host bridges with the patch applied. The situations are:
1) The acpiphp driver won't install ACPI system event handler onto ACPI handles for
PCI/PCIe host bridges, otherwise it will conflict with the PCI host bridge hotplug
driver.
2) If there's no PCI device attached to a PCI hotplug slot or the attached PCI device
is not a P2P bridge, acpiphp installs handle_hotplug_event_func() to handle ACPI
system events. Otherwise handle_hotplug_event_bridge() will be installed.
3) When hot-adding a P2P bridge, acpiphp replaces handle_hotplug_event_func() with
handle_hotplug_event_bridge(), so hot-removal of P2P bridge will be handled by
handle_hotplug_event_bridge().
4) When hot-removing a P2P bridge, acpi replaces handle_hotplug_event_bridge() with
handle_hotplug_event_func(). So P2P bridge hot-add will always be handled by
handle_hotplug_event_func() instead of handle_hotplug_event_bridge()
5) The acpiphp driver still scans for hotplug slots directly attached to PCI host
bridges.
So I think the code in handle_hotplug_event_bridge() to handle P2P hot-addition
is dead. Yijing has helped to test the code by faking ACPI CUSTOM_METHOD, and it
does work as expected.
Regards!
Gerry
>
> I thought that I pointed this out when Yijing Wang or someone else
> pose similar patch.
>
> Thanks
>
> Yinghai
>
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