Re: [PATCH 0/7] ACPI: scan: Split root scanning into 2 steps

Rafael J. Wysocki
2020-12-05T18:46:10Z

On Thursday, December 3, 2020 3:27:27 PM CET Rafael J. Wysocki wrote:
> On Thu, Dec 3, 2020 at 10:53 AM Hans de Goede <hdegoede@redhat.com> wrote:

[cut]

> > That indeed is not necessary if you take the entire set and always enable the
> > new behavior instead of using the module option. I guess we could go that route
> > for 5.12, and get it into next as soon as 5.11-rc1 is available for maximum
> > testing.

I'd prefer to do the whole thing in 5.11-rc and possibly revert something if it
causes problems to occur.

> > Do you want me to do a new version of the series which drops the acpi_defer_add_hids[]
> > thing and the module option and simply always uses the new behavior?
>
> No, something else. Stay tuned.

The patch below illustrates what I'd like to do. It at least doesn't kill my
test-bed system, but also it doesn't cause the enumeration ordering to change
on that system.

It really is three patches in one and (again) I borrowed some code from your
patches in the $subject series. [It is on top of the "ACPI: scan: Add PNP0D80
to the _DEP exceptions list" patch I've just posted.]

Please let me know what you think.

---
drivers/acpi/scan.c | 141 ++++++++++++++++++++++++++++++++++++++++++++--------
1 file changed, 120 insertions(+), 21 deletions(-)

Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -1646,17 +1646,77 @@ void acpi_device_add_finalize(struct acp
kobject_uevent(&device->dev.kobj, KOBJ_ADD);
}

-static int acpi_add_single_object(struct acpi_device **child,
- acpi_handle handle, int type,
- unsigned long long sta)
+/*
+ * List of IDs for which we defer enumeration them to the second pass, because
+ * some of their methods used during addition depend on OpRegions registered by
+ * the drivers for other ACPI devices.
+ */
+static const char * const acpi_defer_enumeration_ids[] = {
+ "BCM2E5B", /* Acer SW3-016 bluetooth HID vs GPIO OpRegs */
+ NULL
+};
+
+static bool acpi_should_defer_enumeration(acpi_handle handle,
+ struct acpi_device_info *info)
+{
+ struct acpi_handle_list dep_devices;
+ acpi_status status;
+ int i;
+
+ if (acpi_info_matches_ids(info, acpi_defer_enumeration_ids))
+ return true;
+
+ /*
+ * We check for _HID here to avoid deferring the enumeration of:
+ * 1. PCI devices
+ * 2. ACPI nodes describing USB ports
+ * However, checking for _HID catches more then just these cases ...
+ */
+ if (!(info->valid & ACPI_VALID_HID))
+ return false;
+
+ status = acpi_evaluate_reference(handle, "_DEP", NULL, &dep_devices);
+ if (ACPI_FAILURE(status))
+ return false;
+
+ for (i = 0; i < dep_devices.count; i++) {
+ struct acpi_device_info *dep_info;
+ bool ignore;
+
+ status = acpi_get_object_info(dep_devices.handles[i], &dep_info);
+ if (ACPI_FAILURE(status))
+ continue;
+
+ ignore = acpi_info_matches_ids(dep_info, acpi_ignore_dep_ids);
+ kfree(dep_info);
+
+ if (ignore)
+ continue;
+
+ return true;
+ }
+
+ return false;
+}
+
+static int __acpi_add_single_object(struct acpi_device **child,
+ acpi_handle handle, int type,
+ unsigned long long sta, bool check_dep)
{
int result;
struct acpi_device *device;
struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
struct acpi_device_info *info = NULL;

- if (handle != ACPI_ROOT_OBJECT && type == ACPI_BUS_TYPE_DEVICE)
+ if (handle != ACPI_ROOT_OBJECT && type == ACPI_BUS_TYPE_DEVICE) {
acpi_get_object_info(handle, &info);
+ if (check_dep && info &&
+ acpi_should_defer_enumeration(handle, info)) {
+ kfree(info);
+ acpi_handle_info(handle, "Missing dependencies\n");
+ return -EAGAIN;
+ }
+ }

device = kzalloc(sizeof(struct acpi_device), GFP_KERNEL);
if (!device) {
@@ -1696,6 +1756,13 @@ static int acpi_add_single_object(struct
return 0;
}

+static int acpi_add_single_object(struct acpi_device **child,
+ acpi_handle handle, int type,
+ unsigned long long sta)
+{
+ return __acpi_add_single_object(child, handle, type, sta, false);
+}
+
static acpi_status acpi_get_resource_memory(struct acpi_resource *ares,
void *context)
{
@@ -1892,8 +1959,8 @@ static void acpi_device_dep_initialize(s
}
}

-static acpi_status acpi_bus_check_add(acpi_handle handle, u32 lvl_not_used,
- void *not_used, void **return_value)
+static acpi_status acpi_bus_check_add(acpi_handle handle, bool check_dep,
+ struct acpi_device **adev_p)
{
struct acpi_device *device = NULL;
int type;
@@ -1913,7 +1980,7 @@ static acpi_status acpi_bus_check_add(ac
return AE_OK;
}

- acpi_add_single_object(&device, handle, type, sta);
+ __acpi_add_single_object(&device, handle, type, sta, check_dep);
if (!device)
return AE_CTRL_DEPTH;

@@ -1921,12 +1988,24 @@ static acpi_status acpi_bus_check_add(ac
acpi_device_dep_initialize(device);

out:
- if (!*return_value)
- *return_value = device;
+ if (!*adev_p)
+ *adev_p = device;

return AE_OK;
}

+static acpi_status acpi_bus_check_add_1(acpi_handle handle, u32 lvl_not_used,
+ void *not_used, void **ret_p)
+{
+ return acpi_bus_check_add(handle, true, (struct acpi_device **)ret_p);
+}
+
+static acpi_status acpi_bus_check_add_2(acpi_handle handle, u32 lvl_not_used,
+ void *not_used, void **ret_p)
+{
+ return acpi_bus_check_add(handle, false, (struct acpi_device **)ret_p);
+}
+
static void acpi_default_enumeration(struct acpi_device *device)
{
/*
@@ -1994,12 +2073,16 @@ static int acpi_scan_attach_handler(stru
return ret;
}

-static void acpi_bus_attach(struct acpi_device *device)
+static void acpi_bus_attach(struct acpi_device *device, bool first_pass)
{
struct acpi_device *child;
+ bool skip = !first_pass && device->flags.visited;
acpi_handle ejd;
int ret;

+ if (skip)
+ goto ok;
+
if (ACPI_SUCCESS(acpi_bus_get_ejd(device->handle, &ejd)))
register_dock_dependent_device(device, ejd);

@@ -2046,9 +2129,9 @@ static void acpi_bus_attach(struct acpi_

ok:
list_for_each_entry(child, &device->children, node)
- acpi_bus_attach(child);
+ acpi_bus_attach(child, first_pass);

- if (device->handler && device->handler->hotplug.notify_online)
+ if (!skip && device->handler && device->handler->hotplug.notify_online)
device->handler->hotplug.notify_online(device);
}

@@ -2066,7 +2149,8 @@ void acpi_walk_dep_device_list(acpi_hand

adev->dep_unmet--;
if (!adev->dep_unmet)
- acpi_bus_attach(adev);
+ acpi_bus_attach(adev, true);
+
list_del(&dep->node);
kfree(dep);
}
@@ -2091,17 +2175,32 @@ EXPORT_SYMBOL_GPL(acpi_walk_dep_device_l
*/
int acpi_bus_scan(acpi_handle handle)
{
- void *device = NULL;
+ struct acpi_device *device = NULL;
+
+ /* Pass 1: Avoid enumerating devices with missing dependencies. */

- if (ACPI_SUCCESS(acpi_bus_check_add(handle, 0, NULL, &device)))
+ if (ACPI_SUCCESS(acpi_bus_check_add(handle, true, &device)))
acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
- acpi_bus_check_add, NULL, NULL, &device);
+ acpi_bus_check_add_1, NULL, NULL,
+ (void **)&device);

- if (device) {
- acpi_bus_attach(device);
- return 0;
- }
- return -ENODEV;
+ if (!device)
+ return -ENODEV;
+
+ acpi_bus_attach(device, true);
+
+ /* Pass 2: Enumerate all of the remaining devices. */
+
+ device = NULL;
+
+ if (ACPI_SUCCESS(acpi_bus_check_add(handle, false, &device)))
+ acpi_walk_namespace(ACPI_TYPE_ANY, handle, ACPI_UINT32_MAX,
+ acpi_bus_check_add_2, NULL, NULL,
+ (void **)&device);
+
+ acpi_bus_attach(device, false);
+
+ return 0;
}
EXPORT_SYMBOL(acpi_bus_scan);