PCI / ACPI: Use acpi_find_child_device() for child devices lookup

It is much more efficient to use acpi_find_child_device()
for child devices lookup in acpi_pci_find_device() and pass
ACPI_COMPANION(dev->parent) to it directly instead of obtaining
ACPI_HANDLE() of ACPI_COMPANION(dev->parent) and passing it to
acpi_find_child() which has to run acpi_bus_get_device() to
obtain ACPI_COMPANION(dev->parent) from that again.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Aaron Lu <aaron.lu@intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/acpi/glue.c b/drivers/acpi/glue.c
index ea77512ad70c..9d200d5029ca 100644
--- a/drivers/acpi/glue.c
+++ b/drivers/acpi/glue.c
@@ -106,6 +106,9 @@ struct acpi_device *acpi_find_child_device(struct acpi_device *parent,
         struct acpi_device *adev, *ret = NULL;
         int ret_score = 0;
 
+        if (!parent)
+                return NULL;
+
         list_for_each_entry(adev, &parent->children, node) {
                 unsigned long long addr;
                 acpi_status status;