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ACPI: scan: Avoid unnecessary second pass in acpi_bus_scan() 

If there are no devices whose enumeration has been deferred after
the first pass in acpi_bus_scan(), the second pass is not necssary,
so avoid it with the help of a new static variable.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>
This commit is contained in:
Rafael J. Wysocki 2020-12-14 21:32:44 +01:00
parent 71da201f38
commit 0de7fb7c86
1 changed files with 10 additions and 1 deletions
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11
drivers/acpi/scan.c
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@ -1910,6 +1910,8 @@ static void acpi_scan_dep_init(struct acpi_device *adev)
mutex_unlock(&acpi_dep_list_lock);
}
static bool acpi_bus_scan_second_pass;
static acpi_status acpi_bus_check_add(acpi_handle handle, bool check_dep,
struct acpi_device **adev_p)
{
@ -1934,8 +1936,10 @@ static acpi_status acpi_bus_check_add(acpi_handle handle, bool check_dep,
if (type == ACPI_BUS_TYPE_DEVICE && check_dep) {
u32 count = acpi_scan_check_dep(handle);
/* Bail out if the number of recorded dependencies is not 0. */
if (count > 0)
if (count > 0) {
acpi_bus_scan_second_pass = true;
return AE_CTRL_DEPTH;
}
}
acpi_add_single_object(&device, handle, type, sta);
@ -2136,6 +2140,8 @@ int acpi_bus_scan(acpi_handle handle)
{
struct acpi_device *device = NULL;
acpi_bus_scan_second_pass = false;
/* Pass 1: Avoid enumerating devices with missing dependencies. */
if (ACPI_SUCCESS(acpi_bus_check_add(handle, true, &device)))
@ -2148,6 +2154,9 @@ int acpi_bus_scan(acpi_handle handle)
acpi_bus_attach(device, true);
if (!acpi_bus_scan_second_pass)
return 0;
/* Pass 2: Enumerate all of the remaining devices. */
device = NULL;