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Commit 122f2672 authored by Henrique de Moraes Holschuh's avatar Henrique de Moraes Holschuh Committed by Matthew Garrett
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thinkpad-acpi: find ACPI video device by synthetic HID 



The Linux ACPI core locates the ACPI video devices for us and marks them
with ACPI_VIDEO_HID.  Use that information to locate the video device
instead of a half-baked hunt for _BCL.

This uncouples the detection of the number of backlight brightness
levels on ThinkPads from the ACPI paths in vid_handle.

With this change, the driver should be able to always detect whether the
ThinkPad uses a 8-level or 16-level brightness scale even on newer
models for which the vid_handle paths have not been updated yet.

It will skip deactivated devices in the ACPI device tree, which is a
change in behaviour.

Signed-off-by: default avatarHenrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: default avatarMatthew Garrett <mjg@redhat.com>
parent 52d7ee55

drivers/platform/x86/thinkpad_acpi.c

+12 −40
Original line number Diff line number Diff line
@@ -6080,13 +6080,18 @@ static struct backlight_ops ibm_backlight_data = { 


/* --------------------------------------------------------------------- */



/*

 * Call _BCL method of video device.  On some ThinkPads this will

 * switch the firmware to the ACPI brightness control mode.

 */



static int __init tpacpi_query_bcl_levels(acpi_handle handle)

{

	struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };

	union acpi_object *obj;

	int rc;



	if (ACPI_SUCCESS(acpi_evaluate_object(handle, NULL, NULL, &buffer))) {

	if (ACPI_SUCCESS(acpi_evaluate_object(handle, "_BCL", NULL, &buffer))) {

		obj = (union acpi_object *)buffer.pointer;

		if (!obj || (obj->type != ACPI_TYPE_PACKAGE)) {

			printk(TPACPI_ERR "Unknown _BCL data, "
@@ -6103,55 +6108,22 @@ static int __init tpacpi_query_bcl_levels(acpi_handle handle) 
	return rc;

}



static acpi_status __init tpacpi_acpi_walk_find_bcl(acpi_handle handle,

					u32 lvl, void *context, void **rv)

{

	char name[ACPI_PATH_SEGMENT_LENGTH];

	struct acpi_buffer buffer = { sizeof(name), &name };



	if (ACPI_SUCCESS(acpi_get_name(handle, ACPI_SINGLE_NAME, &buffer)) &&

	    !strncmp("_BCL", name, sizeof(name) - 1)) {

		BUG_ON(!rv || !*rv);

		**(int **)rv = tpacpi_query_bcl_levels(handle);

		return AE_CTRL_TERMINATE;

	} else {

		return AE_OK;

	}

}



/*

 * Returns 0 (no ACPI _BCL or _BCL invalid), or size of brightness map

 */

static unsigned int __init tpacpi_check_std_acpi_brightness_support(void)

{

	int status;

	acpi_handle video_device;

	int bcl_levels = 0;

	void *bcl_ptr = &bcl_levels;



	if (!vid_handle)

		TPACPI_ACPIHANDLE_INIT(vid);



	if (!vid_handle)

		return 0;



	/*

	 * Search for a _BCL method, and execute it.  This is safe on all

	 * ThinkPads, and as a side-effect, _BCL will place a Lenovo Vista

	 * BIOS in ACPI backlight control mode.  We do NOT have to care

	 * about calling the _BCL method in an enabled video device, any

	 * will do for our purposes.

	 */

	tpacpi_acpi_handle_locate("video", ACPI_VIDEO_HID, &video_device);

	if (video_device)

		bcl_levels = tpacpi_query_bcl_levels(video_device);



	status = acpi_walk_namespace(ACPI_TYPE_METHOD, vid_handle, 3,

				     tpacpi_acpi_walk_find_bcl, NULL, NULL,

				     &bcl_ptr);

	tp_features.bright_acpimode = (bcl_levels > 0);



	if (ACPI_SUCCESS(status) && bcl_levels > 2) {

		tp_features.bright_acpimode = 1;

		return bcl_levels - 2;

	}



	return 0;

	return (bcl_levels > 2) ? (bcl_levels - 2) : 0;

}



/*