2 * Copyright 2012 Advanced Micro Devices, Inc.
4 * Permission is hereby granted, free of charge, to any person obtaining a
5 * copy of this software and associated documentation files (the "Software"),
6 * to deal in the Software without restriction, including without limitation
7 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8 * and/or sell copies of the Software, and to permit persons to whom the
9 * Software is furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice shall be included in
12 * all copies or substantial portions of the Software.
14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
17 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20 * OTHER DEALINGS IN THE SOFTWARE.
24 #include <linux/pci.h>
25 #include <linux/acpi.h>
26 #include <linux/slab.h>
27 #include <linux/power_supply.h>
28 #include <acpi/acpi_drivers.h>
29 #include <acpi/acpi_bus.h>
30 #include <acpi/video.h>
33 #include <drm/drm_crtc_helper.h>
35 #include "radeon_acpi.h"
38 #include <linux/vga_switcheroo.h>
40 #define ACPI_AC_CLASS "ac_adapter"
42 extern void radeon_pm_acpi_event_handler(struct radeon_device *rdev);
44 struct atif_verify_interface {
45 u16 size; /* structure size in bytes (includes size field) */
46 u16 version; /* version */
47 u32 notification_mask; /* supported notifications mask */
48 u32 function_bits; /* supported functions bit vector */
51 struct atif_system_params {
52 u16 size; /* structure size in bytes (includes size field) */
53 u32 valid_mask; /* valid flags mask */
54 u32 flags; /* flags */
55 u8 command_code; /* notify command code */
58 struct atif_sbios_requests {
59 u16 size; /* structure size in bytes (includes size field) */
60 u32 pending; /* pending sbios requests */
61 u8 panel_exp_mode; /* panel expansion mode */
62 u8 thermal_gfx; /* thermal state: target gfx controller */
63 u8 thermal_state; /* thermal state: state id (0: exit state, non-0: state) */
64 u8 forced_power_gfx; /* forced power state: target gfx controller */
65 u8 forced_power_state; /* forced power state: state id */
66 u8 system_power_src; /* system power source */
67 u8 backlight_level; /* panel backlight level (0-255) */
70 #define ATIF_NOTIFY_MASK 0x3
71 #define ATIF_NOTIFY_NONE 0
72 #define ATIF_NOTIFY_81 1
73 #define ATIF_NOTIFY_N 2
75 struct atcs_verify_interface {
76 u16 size; /* structure size in bytes (includes size field) */
77 u16 version; /* version */
78 u32 function_bits; /* supported functions bit vector */
81 #define ATCS_VALID_FLAGS_MASK 0x3
83 struct atcs_pref_req_input {
84 u16 size; /* structure size in bytes (includes size field) */
85 u16 client_id; /* client id (bit 2-0: func num, 7-3: dev num, 15-8: bus num) */
86 u16 valid_flags_mask; /* valid flags mask */
87 u16 flags; /* flags */
88 u8 req_type; /* request type */
89 u8 perf_req; /* performance request */
92 struct atcs_pref_req_output {
93 u16 size; /* structure size in bytes (includes size field) */
94 u8 ret_val; /* return value */
97 /* Call the ATIF method
100 * radeon_atif_call - call an ATIF method
102 * @handle: acpi handle
103 * @function: the ATIF function to execute
104 * @params: ATIF function params
106 * Executes the requested ATIF function (all asics).
107 * Returns a pointer to the acpi output buffer.
109 static union acpi_object *radeon_atif_call(acpi_handle handle, int function,
110 struct acpi_buffer *params)
113 union acpi_object atif_arg_elements[2];
114 struct acpi_object_list atif_arg;
115 struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
118 atif_arg.pointer = &atif_arg_elements[0];
120 atif_arg_elements[0].type = ACPI_TYPE_INTEGER;
121 atif_arg_elements[0].integer.value = function;
124 atif_arg_elements[1].type = ACPI_TYPE_BUFFER;
125 atif_arg_elements[1].buffer.length = params->length;
126 atif_arg_elements[1].buffer.pointer = params->pointer;
128 /* We need a second fake parameter */
129 atif_arg_elements[1].type = ACPI_TYPE_INTEGER;
130 atif_arg_elements[1].integer.value = 0;
133 status = acpi_evaluate_object(handle, "ATIF", &atif_arg, &buffer);
135 /* Fail only if calling the method fails and ATIF is supported */
136 if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
137 DRM_DEBUG_DRIVER("failed to evaluate ATIF got %s\n",
138 acpi_format_exception(status));
139 kfree(buffer.pointer);
143 return buffer.pointer;
147 * radeon_atif_parse_notification - parse supported notifications
149 * @n: supported notifications struct
150 * @mask: supported notifications mask from ATIF
152 * Use the supported notifications mask from ATIF function
153 * ATIF_FUNCTION_VERIFY_INTERFACE to determine what notifications
154 * are supported (all asics).
156 static void radeon_atif_parse_notification(struct radeon_atif_notifications *n, u32 mask)
158 n->display_switch = mask & ATIF_DISPLAY_SWITCH_REQUEST_SUPPORTED;
159 n->expansion_mode_change = mask & ATIF_EXPANSION_MODE_CHANGE_REQUEST_SUPPORTED;
160 n->thermal_state = mask & ATIF_THERMAL_STATE_CHANGE_REQUEST_SUPPORTED;
161 n->forced_power_state = mask & ATIF_FORCED_POWER_STATE_CHANGE_REQUEST_SUPPORTED;
162 n->system_power_state = mask & ATIF_SYSTEM_POWER_SOURCE_CHANGE_REQUEST_SUPPORTED;
163 n->display_conf_change = mask & ATIF_DISPLAY_CONF_CHANGE_REQUEST_SUPPORTED;
164 n->px_gfx_switch = mask & ATIF_PX_GFX_SWITCH_REQUEST_SUPPORTED;
165 n->brightness_change = mask & ATIF_PANEL_BRIGHTNESS_CHANGE_REQUEST_SUPPORTED;
166 n->dgpu_display_event = mask & ATIF_DGPU_DISPLAY_EVENT_SUPPORTED;
170 * radeon_atif_parse_functions - parse supported functions
172 * @f: supported functions struct
173 * @mask: supported functions mask from ATIF
175 * Use the supported functions mask from ATIF function
176 * ATIF_FUNCTION_VERIFY_INTERFACE to determine what functions
177 * are supported (all asics).
179 static void radeon_atif_parse_functions(struct radeon_atif_functions *f, u32 mask)
181 f->system_params = mask & ATIF_GET_SYSTEM_PARAMETERS_SUPPORTED;
182 f->sbios_requests = mask & ATIF_GET_SYSTEM_BIOS_REQUESTS_SUPPORTED;
183 f->select_active_disp = mask & ATIF_SELECT_ACTIVE_DISPLAYS_SUPPORTED;
184 f->lid_state = mask & ATIF_GET_LID_STATE_SUPPORTED;
185 f->get_tv_standard = mask & ATIF_GET_TV_STANDARD_FROM_CMOS_SUPPORTED;
186 f->set_tv_standard = mask & ATIF_SET_TV_STANDARD_IN_CMOS_SUPPORTED;
187 f->get_panel_expansion_mode = mask & ATIF_GET_PANEL_EXPANSION_MODE_FROM_CMOS_SUPPORTED;
188 f->set_panel_expansion_mode = mask & ATIF_SET_PANEL_EXPANSION_MODE_IN_CMOS_SUPPORTED;
189 f->temperature_change = mask & ATIF_TEMPERATURE_CHANGE_NOTIFICATION_SUPPORTED;
190 f->graphics_device_types = mask & ATIF_GET_GRAPHICS_DEVICE_TYPES_SUPPORTED;
194 * radeon_atif_verify_interface - verify ATIF
196 * @handle: acpi handle
197 * @atif: radeon atif struct
199 * Execute the ATIF_FUNCTION_VERIFY_INTERFACE ATIF function
200 * to initialize ATIF and determine what features are supported
202 * returns 0 on success, error on failure.
204 static int radeon_atif_verify_interface(acpi_handle handle,
205 struct radeon_atif *atif)
207 union acpi_object *info;
208 struct atif_verify_interface output;
212 info = radeon_atif_call(handle, ATIF_FUNCTION_VERIFY_INTERFACE, NULL);
216 memset(&output, 0, sizeof(output));
218 size = *(u16 *) info->buffer.pointer;
220 DRM_INFO("ATIF buffer is too small: %zu\n", size);
224 size = min(sizeof(output), size);
226 memcpy(&output, info->buffer.pointer, size);
228 /* TODO: check version? */
229 DRM_DEBUG_DRIVER("ATIF version %u\n", output.version);
231 radeon_atif_parse_notification(&atif->notifications, output.notification_mask);
232 radeon_atif_parse_functions(&atif->functions, output.function_bits);
240 * radeon_atif_get_notification_params - determine notify configuration
242 * @handle: acpi handle
243 * @n: atif notification configuration struct
245 * Execute the ATIF_FUNCTION_GET_SYSTEM_PARAMETERS ATIF function
246 * to determine if a notifier is used and if so which one
247 * (all asics). This is either Notify(VGA, 0x81) or Notify(VGA, n)
248 * where n is specified in the result if a notifier is used.
249 * Returns 0 on success, error on failure.
251 static int radeon_atif_get_notification_params(acpi_handle handle,
252 struct radeon_atif_notification_cfg *n)
254 union acpi_object *info;
255 struct atif_system_params params;
259 info = radeon_atif_call(handle, ATIF_FUNCTION_GET_SYSTEM_PARAMETERS, NULL);
265 size = *(u16 *) info->buffer.pointer;
271 memset(¶ms, 0, sizeof(params));
272 size = min(sizeof(params), size);
273 memcpy(¶ms, info->buffer.pointer, size);
275 DRM_DEBUG_DRIVER("SYSTEM_PARAMS: mask = %#x, flags = %#x\n",
276 params.flags, params.valid_mask);
277 params.flags = params.flags & params.valid_mask;
279 if ((params.flags & ATIF_NOTIFY_MASK) == ATIF_NOTIFY_NONE) {
282 } else if ((params.flags & ATIF_NOTIFY_MASK) == ATIF_NOTIFY_81) {
284 n->command_code = 0x81;
291 n->command_code = params.command_code;
295 DRM_DEBUG_DRIVER("Notification %s, command code = %#x\n",
296 (n->enabled ? "enabled" : "disabled"),
303 * radeon_atif_get_sbios_requests - get requested sbios event
305 * @handle: acpi handle
306 * @req: atif sbios request struct
308 * Execute the ATIF_FUNCTION_GET_SYSTEM_BIOS_REQUESTS ATIF function
309 * to determine what requests the sbios is making to the driver
311 * Returns 0 on success, error on failure.
313 static int radeon_atif_get_sbios_requests(acpi_handle handle,
314 struct atif_sbios_requests *req)
316 union acpi_object *info;
320 info = radeon_atif_call(handle, ATIF_FUNCTION_GET_SYSTEM_BIOS_REQUESTS, NULL);
324 size = *(u16 *)info->buffer.pointer;
329 memset(req, 0, sizeof(*req));
331 size = min(sizeof(*req), size);
332 memcpy(req, info->buffer.pointer, size);
333 DRM_DEBUG_DRIVER("SBIOS pending requests: %#x\n", req->pending);
335 count = hweight32(req->pending);
343 * radeon_atif_handler - handle ATIF notify requests
345 * @rdev: radeon_device pointer
346 * @event: atif sbios request struct
348 * Checks the acpi event and if it matches an atif event,
350 * Returns NOTIFY code
352 int radeon_atif_handler(struct radeon_device *rdev,
353 struct acpi_bus_event *event)
355 struct radeon_atif *atif = &rdev->atif;
356 struct atif_sbios_requests req;
360 DRM_DEBUG_DRIVER("event, device_class = %s, type = %#x\n",
361 event->device_class, event->type);
363 if (strcmp(event->device_class, ACPI_VIDEO_CLASS) != 0)
366 if (!atif->notification_cfg.enabled ||
367 event->type != atif->notification_cfg.command_code)
371 /* Check pending SBIOS requests */
372 handle = ACPI_HANDLE(&rdev->pdev->dev);
373 count = radeon_atif_get_sbios_requests(handle, &req);
378 DRM_DEBUG_DRIVER("ATIF: %d pending SBIOS requests\n", count);
380 if (req.pending & ATIF_PANEL_BRIGHTNESS_CHANGE_REQUEST) {
381 struct radeon_encoder *enc = atif->encoder_for_bl;
384 DRM_DEBUG_DRIVER("Changing brightness to %d\n",
385 req.backlight_level);
387 radeon_set_backlight_level(rdev, enc, req.backlight_level);
389 #if defined(CONFIG_BACKLIGHT_CLASS_DEVICE) || defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE)
390 if (rdev->is_atom_bios) {
391 struct radeon_encoder_atom_dig *dig = enc->enc_priv;
392 backlight_force_update(dig->bl_dev,
393 BACKLIGHT_UPDATE_HOTKEY);
395 struct radeon_encoder_lvds *dig = enc->enc_priv;
396 backlight_force_update(dig->bl_dev,
397 BACKLIGHT_UPDATE_HOTKEY);
402 /* TODO: check other events */
404 /* We've handled the event, stop the notifier chain. The ACPI interface
405 * overloads ACPI_VIDEO_NOTIFY_PROBE, we don't want to send that to
406 * userspace if the event was generated only to signal a SBIOS
412 /* Call the ATCS method
415 * radeon_atcs_call - call an ATCS method
417 * @handle: acpi handle
418 * @function: the ATCS function to execute
419 * @params: ATCS function params
421 * Executes the requested ATCS function (all asics).
422 * Returns a pointer to the acpi output buffer.
424 static union acpi_object *radeon_atcs_call(acpi_handle handle, int function,
425 struct acpi_buffer *params)
428 union acpi_object atcs_arg_elements[2];
429 struct acpi_object_list atcs_arg;
430 struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
433 atcs_arg.pointer = &atcs_arg_elements[0];
435 atcs_arg_elements[0].type = ACPI_TYPE_INTEGER;
436 atcs_arg_elements[0].integer.value = function;
439 atcs_arg_elements[1].type = ACPI_TYPE_BUFFER;
440 atcs_arg_elements[1].buffer.length = params->length;
441 atcs_arg_elements[1].buffer.pointer = params->pointer;
443 /* We need a second fake parameter */
444 atcs_arg_elements[1].type = ACPI_TYPE_INTEGER;
445 atcs_arg_elements[1].integer.value = 0;
448 status = acpi_evaluate_object(handle, "ATCS", &atcs_arg, &buffer);
450 /* Fail only if calling the method fails and ATIF is supported */
451 if (ACPI_FAILURE(status) && status != AE_NOT_FOUND) {
452 DRM_DEBUG_DRIVER("failed to evaluate ATCS got %s\n",
453 acpi_format_exception(status));
454 kfree(buffer.pointer);
458 return buffer.pointer;
462 * radeon_atcs_parse_functions - parse supported functions
464 * @f: supported functions struct
465 * @mask: supported functions mask from ATCS
467 * Use the supported functions mask from ATCS function
468 * ATCS_FUNCTION_VERIFY_INTERFACE to determine what functions
469 * are supported (all asics).
471 static void radeon_atcs_parse_functions(struct radeon_atcs_functions *f, u32 mask)
473 f->get_ext_state = mask & ATCS_GET_EXTERNAL_STATE_SUPPORTED;
474 f->pcie_perf_req = mask & ATCS_PCIE_PERFORMANCE_REQUEST_SUPPORTED;
475 f->pcie_dev_rdy = mask & ATCS_PCIE_DEVICE_READY_NOTIFICATION_SUPPORTED;
476 f->pcie_bus_width = mask & ATCS_SET_PCIE_BUS_WIDTH_SUPPORTED;
480 * radeon_atcs_verify_interface - verify ATCS
482 * @handle: acpi handle
483 * @atcs: radeon atcs struct
485 * Execute the ATCS_FUNCTION_VERIFY_INTERFACE ATCS function
486 * to initialize ATCS and determine what features are supported
488 * returns 0 on success, error on failure.
490 static int radeon_atcs_verify_interface(acpi_handle handle,
491 struct radeon_atcs *atcs)
493 union acpi_object *info;
494 struct atcs_verify_interface output;
498 info = radeon_atcs_call(handle, ATCS_FUNCTION_VERIFY_INTERFACE, NULL);
502 memset(&output, 0, sizeof(output));
504 size = *(u16 *) info->buffer.pointer;
506 DRM_INFO("ATCS buffer is too small: %zu\n", size);
510 size = min(sizeof(output), size);
512 memcpy(&output, info->buffer.pointer, size);
514 /* TODO: check version? */
515 DRM_DEBUG_DRIVER("ATCS version %u\n", output.version);
517 radeon_atcs_parse_functions(&atcs->functions, output.function_bits);
525 * radeon_acpi_is_pcie_performance_request_supported
527 * @rdev: radeon_device pointer
529 * Check if the ATCS pcie_perf_req and pcie_dev_rdy methods
530 * are supported (all asics).
531 * returns true if supported, false if not.
533 bool radeon_acpi_is_pcie_performance_request_supported(struct radeon_device *rdev)
535 struct radeon_atcs *atcs = &rdev->atcs;
537 if (atcs->functions.pcie_perf_req && atcs->functions.pcie_dev_rdy)
544 * radeon_acpi_pcie_notify_device_ready
546 * @rdev: radeon_device pointer
548 * Executes the PCIE_DEVICE_READY_NOTIFICATION method
550 * returns 0 on success, error on failure.
552 int radeon_acpi_pcie_notify_device_ready(struct radeon_device *rdev)
555 union acpi_object *info;
556 struct radeon_atcs *atcs = &rdev->atcs;
558 /* Get the device handle */
559 handle = ACPI_HANDLE(&rdev->pdev->dev);
563 if (!atcs->functions.pcie_dev_rdy)
566 info = radeon_atcs_call(handle, ATCS_FUNCTION_PCIE_DEVICE_READY_NOTIFICATION, NULL);
576 * radeon_acpi_pcie_performance_request
578 * @rdev: radeon_device pointer
579 * @perf_req: requested perf level (pcie gen speed)
580 * @advertise: set advertise caps flag if set
582 * Executes the PCIE_PERFORMANCE_REQUEST method to
583 * change the pcie gen speed (all asics).
584 * returns 0 on success, error on failure.
586 int radeon_acpi_pcie_performance_request(struct radeon_device *rdev,
587 u8 perf_req, bool advertise)
590 union acpi_object *info;
591 struct radeon_atcs *atcs = &rdev->atcs;
592 struct atcs_pref_req_input atcs_input;
593 struct atcs_pref_req_output atcs_output;
594 struct acpi_buffer params;
598 /* Get the device handle */
599 handle = ACPI_HANDLE(&rdev->pdev->dev);
603 if (!atcs->functions.pcie_perf_req)
606 atcs_input.size = sizeof(struct atcs_pref_req_input);
607 /* client id (bit 2-0: func num, 7-3: dev num, 15-8: bus num) */
608 atcs_input.client_id = rdev->pdev->devfn | (rdev->pdev->bus->number << 8);
609 atcs_input.valid_flags_mask = ATCS_VALID_FLAGS_MASK;
610 atcs_input.flags = ATCS_WAIT_FOR_COMPLETION;
612 atcs_input.flags |= ATCS_ADVERTISE_CAPS;
613 atcs_input.req_type = ATCS_PCIE_LINK_SPEED;
614 atcs_input.perf_req = perf_req;
616 params.length = sizeof(struct atcs_pref_req_input);
617 params.pointer = &atcs_input;
620 info = radeon_atcs_call(handle, ATCS_FUNCTION_PCIE_PERFORMANCE_REQUEST, ¶ms);
624 memset(&atcs_output, 0, sizeof(atcs_output));
626 size = *(u16 *) info->buffer.pointer;
628 DRM_INFO("ATCS buffer is too small: %zu\n", size);
632 size = min(sizeof(atcs_output), size);
634 memcpy(&atcs_output, info->buffer.pointer, size);
638 switch (atcs_output.ret_val) {
639 case ATCS_REQUEST_REFUSED:
642 case ATCS_REQUEST_COMPLETE:
644 case ATCS_REQUEST_IN_PROGRESS:
654 * radeon_acpi_event - handle notify events
656 * @nb: notifier block
660 * Calls relevant radeon functions in response to various
662 * Returns NOTIFY code
664 static int radeon_acpi_event(struct notifier_block *nb,
668 struct radeon_device *rdev = container_of(nb, struct radeon_device, acpi_nb);
669 struct acpi_bus_event *entry = (struct acpi_bus_event *)data;
671 if (strcmp(entry->device_class, ACPI_AC_CLASS) == 0) {
672 if (power_supply_is_system_supplied() > 0)
673 DRM_DEBUG_DRIVER("pm: AC\n");
675 DRM_DEBUG_DRIVER("pm: DC\n");
677 radeon_pm_acpi_event_handler(rdev);
680 /* Check for pending SBIOS requests */
681 return radeon_atif_handler(rdev, entry);
684 /* Call all ACPI methods here */
686 * radeon_acpi_init - init driver acpi support
688 * @rdev: radeon_device pointer
690 * Verifies the AMD ACPI interfaces and registers with the acpi
691 * notifier chain (all asics).
692 * Returns 0 on success, error on failure.
694 int radeon_acpi_init(struct radeon_device *rdev)
697 struct radeon_atif *atif = &rdev->atif;
698 struct radeon_atcs *atcs = &rdev->atcs;
701 /* Get the device handle */
702 handle = ACPI_HANDLE(&rdev->pdev->dev);
704 /* No need to proceed if we're sure that ATIF is not supported */
705 if (!ASIC_IS_AVIVO(rdev) || !rdev->bios || !handle)
708 /* Call the ATCS method */
709 ret = radeon_atcs_verify_interface(handle, atcs);
711 DRM_DEBUG_DRIVER("Call to ATCS verify_interface failed: %d\n", ret);
714 /* Call the ATIF method */
715 ret = radeon_atif_verify_interface(handle, atif);
717 DRM_DEBUG_DRIVER("Call to ATIF verify_interface failed: %d\n", ret);
721 if (atif->notifications.brightness_change) {
722 struct drm_encoder *tmp;
723 struct radeon_encoder *target = NULL;
725 /* Find the encoder controlling the brightness */
726 list_for_each_entry(tmp, &rdev->ddev->mode_config.encoder_list,
728 struct radeon_encoder *enc = to_radeon_encoder(tmp);
730 if ((enc->devices & (ATOM_DEVICE_LCD_SUPPORT)) &&
732 if (rdev->is_atom_bios) {
733 struct radeon_encoder_atom_dig *dig = enc->enc_priv;
739 struct radeon_encoder_lvds *dig = enc->enc_priv;
748 atif->encoder_for_bl = target;
750 /* Brightness change notification is enabled, but we
751 * didn't find a backlight controller, this should
754 DRM_ERROR("Cannot find a backlight controller\n");
758 if (atif->functions.sbios_requests && !atif->functions.system_params) {
759 /* XXX check this workraround, if sbios request function is
760 * present we have to see how it's configured in the system
763 atif->functions.system_params = true;
766 if (atif->functions.system_params) {
767 ret = radeon_atif_get_notification_params(handle,
768 &atif->notification_cfg);
770 DRM_DEBUG_DRIVER("Call to GET_SYSTEM_PARAMS failed: %d\n",
772 /* Disable notification */
773 atif->notification_cfg.enabled = false;
778 rdev->acpi_nb.notifier_call = radeon_acpi_event;
779 register_acpi_notifier(&rdev->acpi_nb);
785 * radeon_acpi_fini - tear down driver acpi support
787 * @rdev: radeon_device pointer
789 * Unregisters with the acpi notifier chain (all asics).
791 void radeon_acpi_fini(struct radeon_device *rdev)
793 unregister_acpi_notifier(&rdev->acpi_nb);