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Commit 5f8902ac authored by Lin Ming's avatar Lin Ming Committed by Len Brown
Browse files

ACPICA: AcpiGetDevices: Eliminate unnecessary _STA calls 



In the case where a specific _HID is requested, do not run _STA
until a _HID match is found. This eliminates potentially dozens
of _STA calls during a search for a particular device/HID.

Signed-off-by: default avatarLin Ming <ming.m.lin@intel.com>
Signed-off-by: default avatarBob Moore <robert.moore@intel.com>
Signed-off-by: default avatarLen Brown <len.brown@intel.com>
parent a8357b0c

drivers/acpi/acpica/nsxfeval.c

+33 −19
Original line number Diff line number Diff line
@@ -562,25 +562,20 @@ acpi_ns_get_device_callback(acpi_handle obj_handle, 
		return (AE_BAD_PARAMETER);

	}



	/* Run _STA to determine if device is present */



	status = acpi_ut_execute_STA(node, &flags);

	if (ACPI_FAILURE(status)) {

		return (AE_CTRL_DEPTH);

	}



	if (!(flags & ACPI_STA_DEVICE_PRESENT) &&

	    !(flags & ACPI_STA_DEVICE_FUNCTIONING)) {

	/*

		 * Don't examine the children of the device only when the

		 * device is neither present nor functional. See ACPI spec,

		 * description of _STA for more information.

	 * First, filter based on the device HID and CID.

	 *

	 * 01/2010: For this case where a specific HID is requested, we don't

	 * want to run _STA until we have an actual HID match. Thus, we will

	 * not unnecessarily execute _STA on devices for which the caller

	 * doesn't care about. Previously, _STA was executed unconditionally

	 * on all devices found here.

	 *

	 * A side-effect of this change is that now we will continue to search

	 * for a matching HID even under device trees where the parent device

	 * would have returned a _STA that indicates it is not present or

	 * not functioning (thus aborting the search on that branch).

	 */

		return (AE_CTRL_DEPTH);

	}



	/* Filter based on device HID & CID */



	if (info->hid != NULL) {

		status = acpi_ut_execute_HID(node, &hid);

		if (status == AE_NOT_FOUND) {
@@ -620,6 +615,25 @@ acpi_ns_get_device_callback(acpi_handle obj_handle, 
		}

	}



	/* Run _STA to determine if device is present */



	status = acpi_ut_execute_STA(node, &flags);

	if (ACPI_FAILURE(status)) {

		return (AE_CTRL_DEPTH);

	}



	if (!(flags & ACPI_STA_DEVICE_PRESENT) &&

	    !(flags & ACPI_STA_DEVICE_FUNCTIONING)) {

		/*

		 * Don't examine the children of the device only when the

		 * device is neither present nor functional. See ACPI spec,

		 * description of _STA for more information.

		 */

		return (AE_CTRL_DEPTH);

	}



	/* We have a valid device, invoke the user function */



	status = info->user_function(obj_handle, nesting_level, info->context,

				     return_value);

	return (status);