From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Subject: ACPI: Rework acpi_get_child() to be more efficient
Observe that acpi_get_child() doesn't need to use the helper
struct acpi_find_child structure and change it to work without it.
Also, using acpi_get_object_info() to get the output of _ADR for the
given device is overkill, because that function does much more than
just evaluating _ADR (let alone the additional memory allocation
done by it).
Moreover, acpi_get_child() doesn't need to loop any more once it has
found a matching handle, so make it stop in that case. To prevent
the results from changing, make it use do_acpi_find_child() as
a post-order callback.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
---
The difference from the previous version is the replacement of
acpi_get_object_info() with the direct execution of _ADR, which is
more straightforward.
Thanks,
Rafael
---
drivers/acpi/glue.c | 33 ++++++++++++---------------------
1 file changed, 12 insertions(+), 21 deletions(-)
Index: linux/drivers/acpi/glue.c
===================================================================
--- linux.orig/drivers/acpi/glue.c
+++ linux/drivers/acpi/glue.c
@@ -93,40 +93,31 @@ static int acpi_find_bridge_device(struc
return ret;
}
-/* Get device's handler per its address under its parent */
-struct acpi_find_child {
- acpi_handle handle;
- u64 address;
-};
-
-static acpi_status
-do_acpi_find_child(acpi_handle handle, u32 lvl, void *context, void **rv)
+static acpi_status do_acpi_find_child(acpi_handle handle, u32 lvl_not_used,
+ void *addr_p, void **ret_p)
{
+ unsigned long long addr;
acpi_status status;
- struct acpi_device_info *info;
- struct acpi_find_child *find = context;
- status = acpi_get_object_info(handle, &info);
- if (ACPI_SUCCESS(status)) {
- if ((info->address == find->address)
- && (info->valid & ACPI_VALID_ADR))
- find->handle = handle;
- kfree(info);
+ status = acpi_evaluate_integer(handle, METHOD_NAME__ADR, NULL, &addr);
+ if (ACPI_SUCCESS(status) && addr == *((u64 *)addr_p)) {
+ *ret_p = handle;
+ return AE_CTRL_TERMINATE;
}
return AE_OK;
}
acpi_handle acpi_get_child(acpi_handle parent, u64 address)
{
- struct acpi_find_child find = { NULL, address };
+ void *ret = NULL;
if (!parent)
return NULL;
- acpi_walk_namespace(ACPI_TYPE_DEVICE, parent,
- 1, do_acpi_find_child, NULL, &find, NULL);
- return find.handle;
-}
+ acpi_walk_namespace(ACPI_TYPE_DEVICE, parent, 1, NULL,
+ do_acpi_find_child, &address, &ret);
+ return (acpi_handle)ret;
+}
EXPORT_SYMBOL(acpi_get_child);
static int acpi_bind_one(struct device *dev, acpi_handle handle)
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
