xref: /linux/drivers/gpu/drm/i915/display/intel_dp_aux_backlight.c (revision 7c04b6c7e9c5b1d8121b4fe88bc47daed2ff8665)
1 /*
2  * Copyright © 2015 Intel Corporation
3  *
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:
10  *
11  * The above copyright notice and this permission notice (including the next
12  * paragraph) shall be included in all copies or substantial portions of the
13  * Software.
14  *
15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
21  * IN THE SOFTWARE.
22  *
23  */
24 
25 /*
26  * Laptops with Intel GPUs which have panels that support controlling the
27  * backlight through DP AUX can actually use two different interfaces: Intel's
28  * proprietary DP AUX backlight interface, and the standard VESA backlight
29  * interface. Unfortunately, at the time of writing this a lot of laptops will
30  * advertise support for the standard VESA backlight interface when they
31  * don't properly support it. However, on these systems the Intel backlight
32  * interface generally does work properly. Additionally, these systems will
33  * usually just indicate that they use PWM backlight controls in their VBIOS
34  * for some reason.
35  */
36 
37 #include <drm/drm_print.h>
38 
39 #include "i915_utils.h"
40 #include "intel_backlight.h"
41 #include "intel_display_core.h"
42 #include "intel_display_types.h"
43 #include "intel_dp.h"
44 #include "intel_dp_aux_backlight.h"
45 
46 /*
47  * DP AUX registers for Intel's proprietary HDR backlight interface. We define
48  * them here since we'll likely be the only driver to ever use these.
49  */
50 #define INTEL_EDP_HDR_TCON_CAP0                                        0x340
51 
52 #define INTEL_EDP_HDR_TCON_CAP1                                        0x341
53 # define INTEL_EDP_HDR_TCON_2084_DECODE_CAP                           BIT(0)
54 # define INTEL_EDP_HDR_TCON_2020_GAMUT_CAP                            BIT(1)
55 # define INTEL_EDP_HDR_TCON_TONE_MAPPING_CAP                          BIT(2)
56 # define INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_CAP                   BIT(3)
57 # define INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP                       BIT(4)
58 # define INTEL_EDP_HDR_TCON_OPTIMIZATION_CAP                          BIT(5)
59 # define INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_CAP                       BIT(6)
60 # define INTEL_EDP_HDR_TCON_SRGB_TO_PANEL_GAMUT_CONVERSION_CAP        BIT(7)
61 
62 #define INTEL_EDP_HDR_TCON_CAP2                                        0x342
63 # define INTEL_EDP_SDR_TCON_BRIGHTNESS_AUX_CAP                        BIT(0)
64 
65 #define INTEL_EDP_HDR_TCON_CAP3                                        0x343
66 
67 #define INTEL_EDP_HDR_GETSET_CTRL_PARAMS                               0x344
68 # define INTEL_EDP_HDR_TCON_2084_DECODE_ENABLE                        BIT(0)
69 # define INTEL_EDP_HDR_TCON_2020_GAMUT_ENABLE                         BIT(1)
70 # define INTEL_EDP_HDR_TCON_TONE_MAPPING_ENABLE                       BIT(2)
71 # define INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_ENABLE                BIT(3)
72 # define INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE                     BIT(4)
73 # define INTEL_EDP_HDR_TCON_SRGB_TO_PANEL_GAMUT_ENABLE                BIT(5)
74 /* Bit 6 is reserved */
75 # define INTEL_EDP_HDR_TCON_SDP_OVERRIDE_AUX			      BIT(7)
76 
77 #define INTEL_EDP_HDR_CONTENT_LUMINANCE                                0x346
78 #define INTEL_EDP_HDR_PANEL_LUMINANCE_OVERRIDE                         0x34A
79 #define INTEL_EDP_SDR_LUMINANCE_LEVEL                                  0x352
80 #define INTEL_EDP_BRIGHTNESS_NITS_LSB                                  0x354
81 #define INTEL_EDP_BRIGHTNESS_NITS_MSB                                  0x355
82 #define INTEL_EDP_BRIGHTNESS_DELAY_FRAMES                              0x356
83 #define INTEL_EDP_BRIGHTNESS_PER_FRAME_STEPS                           0x357
84 
85 #define INTEL_EDP_BRIGHTNESS_OPTIMIZATION_0                            0x358
86 # define INTEL_EDP_TCON_USAGE_MASK                             GENMASK(0, 3)
87 # define INTEL_EDP_TCON_USAGE_UNKNOWN                                    0x0
88 # define INTEL_EDP_TCON_USAGE_DESKTOP                                    0x1
89 # define INTEL_EDP_TCON_USAGE_FULL_SCREEN_MEDIA                          0x2
90 # define INTEL_EDP_TCON_USAGE_FULL_SCREEN_GAMING                         0x3
91 # define INTEL_EDP_TCON_POWER_MASK                                    BIT(4)
92 # define INTEL_EDP_TCON_POWER_DC                                    (0 << 4)
93 # define INTEL_EDP_TCON_POWER_AC                                    (1 << 4)
94 # define INTEL_EDP_TCON_OPTIMIZATION_STRENGTH_MASK             GENMASK(5, 7)
95 
96 #define INTEL_EDP_BRIGHTNESS_OPTIMIZATION_1                            0x359
97 
98 enum intel_dp_aux_backlight_modparam {
99 	INTEL_DP_AUX_BACKLIGHT_AUTO = -1,
100 	INTEL_DP_AUX_BACKLIGHT_OFF = 0,
101 	INTEL_DP_AUX_BACKLIGHT_ON = 1,
102 	INTEL_DP_AUX_BACKLIGHT_FORCE_VESA = 2,
103 	INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL = 3,
104 };
105 
106 static bool is_intel_tcon_cap(const u8 tcon_cap[4])
107 {
108 	return tcon_cap[0] >= 1;
109 }
110 
111 /* Intel EDP backlight callbacks */
112 static bool
113 intel_dp_aux_supports_hdr_backlight(struct intel_connector *connector)
114 {
115 	struct intel_display *display = to_intel_display(connector);
116 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
117 	struct drm_dp_aux *aux = &intel_dp->aux;
118 	struct intel_panel *panel = &connector->panel;
119 	int ret;
120 	u8 tcon_cap[4];
121 
122 	intel_dp_wait_source_oui(intel_dp);
123 
124 	ret = drm_dp_dpcd_read(aux, INTEL_EDP_HDR_TCON_CAP0, tcon_cap, sizeof(tcon_cap));
125 	if (ret != sizeof(tcon_cap))
126 		return false;
127 
128 	drm_dbg_kms(display->drm,
129 		    "[CONNECTOR:%d:%s] Detected %s HDR backlight interface version %d\n",
130 		    connector->base.base.id, connector->base.name,
131 		    is_intel_tcon_cap(tcon_cap) ? "Intel" : "unsupported", tcon_cap[0]);
132 
133 	if (!is_intel_tcon_cap(tcon_cap))
134 		return false;
135 
136 	if (!(tcon_cap[1] & INTEL_EDP_HDR_TCON_BRIGHTNESS_NITS_CAP))
137 		return false;
138 
139 	/*
140 	 * If we don't have HDR static metadata there is no way to
141 	 * runtime detect used range for nits based control. For now
142 	 * do not use Intel proprietary eDP backlight control if we
143 	 * don't have this data in panel EDID. In case we find panel
144 	 * which supports only nits based control, but doesn't provide
145 	 * HDR static metadata we need to start maintaining table of
146 	 * ranges for such panels.
147 	 */
148 	if (display->params.enable_dpcd_backlight != INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL &&
149 	    !(connector->base.hdr_sink_metadata.hdmi_type1.metadata_type &
150 	      BIT(HDMI_STATIC_METADATA_TYPE1))) {
151 		drm_info(display->drm,
152 			 "[CONNECTOR:%d:%s] Panel is missing HDR static metadata. Possible support for Intel HDR backlight interface is not used. If your backlight controls don't work try booting with i915.enable_dpcd_backlight=%d. needs this, please file a _new_ bug report on drm/i915, see " FDO_BUG_URL " for details.\n",
153 			 connector->base.base.id, connector->base.name,
154 			 INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL);
155 		return false;
156 	}
157 
158 	panel->backlight.edp.intel_cap.sdr_uses_aux =
159 		tcon_cap[2] & INTEL_EDP_SDR_TCON_BRIGHTNESS_AUX_CAP;
160 	panel->backlight.edp.intel_cap.supports_2084_decode =
161 		tcon_cap[1] & INTEL_EDP_HDR_TCON_2084_DECODE_CAP;
162 	panel->backlight.edp.intel_cap.supports_2020_gamut =
163 		tcon_cap[1] & INTEL_EDP_HDR_TCON_2020_GAMUT_CAP;
164 	panel->backlight.edp.intel_cap.supports_segmented_backlight =
165 		tcon_cap[1] & INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_CAP;
166 	panel->backlight.edp.intel_cap.supports_sdp_colorimetry =
167 		tcon_cap[1] & INTEL_EDP_HDR_TCON_SDP_COLORIMETRY_CAP;
168 	panel->backlight.edp.intel_cap.supports_tone_mapping =
169 		tcon_cap[1] & INTEL_EDP_HDR_TCON_TONE_MAPPING_CAP;
170 
171 	return true;
172 }
173 
174 static u32
175 intel_dp_aux_hdr_get_backlight(struct intel_connector *connector, enum pipe pipe)
176 {
177 	struct intel_display *display = to_intel_display(connector);
178 	struct intel_panel *panel = &connector->panel;
179 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
180 	u8 tmp;
181 	u8 buf[2] = {};
182 
183 	if (drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &tmp) != 1) {
184 		drm_err(display->drm,
185 			"[CONNECTOR:%d:%s] Failed to read current backlight mode from DPCD\n",
186 			connector->base.base.id, connector->base.name);
187 		return 0;
188 	}
189 
190 	if (!(tmp & INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE)) {
191 		if (!panel->backlight.edp.intel_cap.sdr_uses_aux) {
192 			u32 pwm_level = panel->backlight.pwm_funcs->get(connector, pipe);
193 
194 			return intel_backlight_level_from_pwm(connector, pwm_level);
195 		}
196 
197 		/* Assume 100% brightness if backlight controls aren't enabled yet */
198 		return panel->backlight.max;
199 	}
200 
201 	if (drm_dp_dpcd_read(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
202 			     sizeof(buf)) != sizeof(buf)) {
203 		drm_err(display->drm,
204 			"[CONNECTOR:%d:%s] Failed to read brightness from DPCD\n",
205 			connector->base.base.id, connector->base.name);
206 		return 0;
207 	}
208 
209 	return (buf[1] << 8 | buf[0]);
210 }
211 
212 static void
213 intel_dp_aux_hdr_set_aux_backlight(const struct drm_connector_state *conn_state, u32 level)
214 {
215 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
216 	struct drm_device *dev = connector->base.dev;
217 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
218 	u8 buf[4] = {};
219 
220 	buf[0] = level & 0xFF;
221 	buf[1] = (level & 0xFF00) >> 8;
222 
223 	if (drm_dp_dpcd_write(&intel_dp->aux, INTEL_EDP_BRIGHTNESS_NITS_LSB, buf,
224 			      sizeof(buf)) != sizeof(buf))
225 		drm_err(dev, "[CONNECTOR:%d:%s] Failed to write brightness level to DPCD\n",
226 			connector->base.base.id, connector->base.name);
227 }
228 
229 static bool
230 intel_dp_in_hdr_mode(const struct drm_connector_state *conn_state)
231 {
232 	struct hdr_output_metadata *hdr_metadata;
233 
234 	if (!conn_state->hdr_output_metadata)
235 		return false;
236 
237 	hdr_metadata = conn_state->hdr_output_metadata->data;
238 
239 	return hdr_metadata->hdmi_metadata_type1.eotf == HDMI_EOTF_SMPTE_ST2084;
240 }
241 
242 static void
243 intel_dp_aux_hdr_set_backlight(const struct drm_connector_state *conn_state, u32 level)
244 {
245 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
246 	struct intel_panel *panel = &connector->panel;
247 
248 	if (intel_dp_in_hdr_mode(conn_state) ||
249 	    panel->backlight.edp.intel_cap.sdr_uses_aux) {
250 		intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
251 	} else {
252 		const u32 pwm_level = intel_backlight_level_to_pwm(connector, level);
253 
254 		intel_backlight_set_pwm_level(conn_state, pwm_level);
255 	}
256 }
257 
258 static void
259 intel_dp_aux_write_content_luminance(struct intel_connector *connector,
260 				     struct hdr_output_metadata *hdr_metadata)
261 {
262 	struct intel_display *display = to_intel_display(connector);
263 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
264 	int ret;
265 	u8 buf[4];
266 
267 	if (!intel_dp_has_gamut_metadata_dip(connector->encoder))
268 		return;
269 
270 	buf[0] = hdr_metadata->hdmi_metadata_type1.max_cll & 0xFF;
271 	buf[1] = (hdr_metadata->hdmi_metadata_type1.max_cll & 0xFF00) >> 8;
272 	buf[2] = hdr_metadata->hdmi_metadata_type1.max_fall & 0xFF;
273 	buf[3] = (hdr_metadata->hdmi_metadata_type1.max_fall & 0xFF00) >> 8;
274 
275 	ret = drm_dp_dpcd_write(&intel_dp->aux,
276 				INTEL_EDP_HDR_CONTENT_LUMINANCE,
277 				buf, sizeof(buf));
278 	if (ret < 0)
279 		drm_dbg_kms(display->drm,
280 			    "Content Luminance DPCD reg write failed, err:-%d\n",
281 			    ret);
282 }
283 
284 static void
285 intel_dp_aux_fill_hdr_tcon_params(const struct drm_connector_state *conn_state, u8 *ctrl)
286 {
287 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
288 	struct intel_panel *panel = &connector->panel;
289 	struct intel_display *display = to_intel_display(connector);
290 
291 	/*
292 	 * According to spec segmented backlight needs to be set whenever panel is in
293 	 * HDR mode.
294 	 */
295 	if (intel_dp_in_hdr_mode(conn_state)) {
296 		*ctrl |= INTEL_EDP_HDR_TCON_SEGMENTED_BACKLIGHT_ENABLE;
297 		*ctrl |= INTEL_EDP_HDR_TCON_2084_DECODE_ENABLE;
298 	}
299 
300 	if (DISPLAY_VER(display) < 11)
301 		*ctrl &= ~INTEL_EDP_HDR_TCON_TONE_MAPPING_ENABLE;
302 
303 	if (panel->backlight.edp.intel_cap.supports_2020_gamut &&
304 	    (conn_state->colorspace == DRM_MODE_COLORIMETRY_BT2020_RGB ||
305 	     conn_state->colorspace == DRM_MODE_COLORIMETRY_BT2020_YCC ||
306 	     conn_state->colorspace == DRM_MODE_COLORIMETRY_BT2020_CYCC))
307 		*ctrl |= INTEL_EDP_HDR_TCON_2020_GAMUT_ENABLE;
308 
309 	if (panel->backlight.edp.intel_cap.supports_sdp_colorimetry &&
310 	    intel_dp_has_gamut_metadata_dip(connector->encoder))
311 		*ctrl |= INTEL_EDP_HDR_TCON_SDP_OVERRIDE_AUX;
312 	else
313 		*ctrl &= ~INTEL_EDP_HDR_TCON_SDP_OVERRIDE_AUX;
314 }
315 
316 static void
317 intel_dp_aux_hdr_enable_backlight(const struct intel_crtc_state *crtc_state,
318 				  const struct drm_connector_state *conn_state, u32 level)
319 {
320 	struct intel_display *display = to_intel_display(crtc_state);
321 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
322 	struct intel_panel *panel = &connector->panel;
323 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
324 	struct hdr_output_metadata *hdr_metadata;
325 	int ret;
326 	u8 old_ctrl, ctrl;
327 
328 	intel_dp_wait_source_oui(intel_dp);
329 
330 	ret = drm_dp_dpcd_readb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, &old_ctrl);
331 	if (ret != 1) {
332 		drm_err(display->drm,
333 			"[CONNECTOR:%d:%s] Failed to read current backlight control mode: %d\n",
334 			connector->base.base.id, connector->base.name, ret);
335 		return;
336 	}
337 
338 	ctrl = old_ctrl;
339 	if (intel_dp_in_hdr_mode(conn_state) ||
340 	    panel->backlight.edp.intel_cap.sdr_uses_aux) {
341 		ctrl |= INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
342 
343 		intel_dp_aux_hdr_set_aux_backlight(conn_state, level);
344 	} else {
345 		u32 pwm_level = intel_backlight_level_to_pwm(connector, level);
346 
347 		panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);
348 
349 		ctrl &= ~INTEL_EDP_HDR_TCON_BRIGHTNESS_AUX_ENABLE;
350 	}
351 
352 	intel_dp_aux_fill_hdr_tcon_params(conn_state, &ctrl);
353 
354 	if (ctrl != old_ctrl &&
355 	    drm_dp_dpcd_writeb(&intel_dp->aux, INTEL_EDP_HDR_GETSET_CTRL_PARAMS, ctrl) != 1)
356 		drm_err(display->drm,
357 			"[CONNECTOR:%d:%s] Failed to configure DPCD brightness controls\n",
358 			connector->base.base.id, connector->base.name);
359 
360 	if (intel_dp_in_hdr_mode(conn_state)) {
361 		hdr_metadata = conn_state->hdr_output_metadata->data;
362 		intel_dp_aux_write_content_luminance(connector, hdr_metadata);
363 	}
364 }
365 
366 static void
367 intel_dp_aux_hdr_disable_backlight(const struct drm_connector_state *conn_state, u32 level)
368 {
369 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
370 	struct intel_panel *panel = &connector->panel;
371 
372 	/* Nothing to do for AUX based backlight controls */
373 	if (panel->backlight.edp.intel_cap.sdr_uses_aux)
374 		return;
375 
376 	/* Note we want the actual pwm_level to be 0, regardless of pwm_min */
377 	panel->backlight.pwm_funcs->disable(conn_state, intel_backlight_invert_pwm_level(connector, 0));
378 }
379 
380 static const char *dpcd_vs_pwm_str(bool aux)
381 {
382 	return aux ? "DPCD" : "PWM";
383 }
384 
385 static void
386 intel_dp_aux_write_panel_luminance_override(struct intel_connector *connector)
387 {
388 	struct intel_display *display = to_intel_display(connector);
389 	struct intel_panel *panel = &connector->panel;
390 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
391 	int ret;
392 	u8 buf[4] = {};
393 
394 	buf[0] = panel->backlight.min & 0xFF;
395 	buf[1] = (panel->backlight.min & 0xFF00) >> 8;
396 	buf[2] = panel->backlight.max & 0xFF;
397 	buf[3] = (panel->backlight.max & 0xFF00) >> 8;
398 
399 	ret = drm_dp_dpcd_write(&intel_dp->aux,
400 				INTEL_EDP_HDR_PANEL_LUMINANCE_OVERRIDE,
401 				buf, sizeof(buf));
402 	if (ret < 0)
403 		drm_dbg_kms(display->drm,
404 			    "Panel Luminance DPCD reg write failed, err:-%d\n",
405 			    ret);
406 }
407 
408 static int
409 intel_dp_aux_hdr_setup_backlight(struct intel_connector *connector, enum pipe pipe)
410 {
411 	struct intel_display *display = to_intel_display(connector);
412 	struct intel_panel *panel = &connector->panel;
413 	struct drm_luminance_range_info *luminance_range =
414 		&connector->base.display_info.luminance_range;
415 	int ret;
416 
417 	drm_dbg_kms(display->drm,
418 		    "[CONNECTOR:%d:%s] SDR backlight is controlled through %s\n",
419 		    connector->base.base.id, connector->base.name,
420 		    dpcd_vs_pwm_str(panel->backlight.edp.intel_cap.sdr_uses_aux));
421 
422 	if (!panel->backlight.edp.intel_cap.sdr_uses_aux) {
423 		ret = panel->backlight.pwm_funcs->setup(connector, pipe);
424 		if (ret < 0) {
425 			drm_err(display->drm,
426 				"[CONNECTOR:%d:%s] Failed to setup SDR backlight controls through PWM: %d\n",
427 				connector->base.base.id, connector->base.name, ret);
428 			return ret;
429 		}
430 	}
431 
432 	if (luminance_range->max_luminance) {
433 		panel->backlight.max = luminance_range->max_luminance;
434 		panel->backlight.min = luminance_range->min_luminance;
435 	} else {
436 		panel->backlight.max = 512;
437 		panel->backlight.min = 0;
438 	}
439 
440 	intel_dp_aux_write_panel_luminance_override(connector);
441 
442 	drm_dbg_kms(display->drm,
443 		    "[CONNECTOR:%d:%s] Using AUX HDR interface for backlight control (range %d..%d)\n",
444 		    connector->base.base.id, connector->base.name,
445 		    panel->backlight.min, panel->backlight.max);
446 
447 	panel->backlight.level = intel_dp_aux_hdr_get_backlight(connector, pipe);
448 	panel->backlight.enabled = panel->backlight.level != 0;
449 
450 	return 0;
451 }
452 
453 /* VESA backlight callbacks */
454 static u32 intel_dp_aux_vesa_get_backlight(struct intel_connector *connector, enum pipe unused)
455 {
456 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
457 	struct intel_panel *panel = &connector->panel;
458 	u8 buf[3];
459 	u32 val = 0;
460 	int ret;
461 
462 	if (panel->backlight.edp.vesa.luminance_control_support) {
463 		ret = drm_dp_dpcd_read(&intel_dp->aux, DP_EDP_PANEL_TARGET_LUMINANCE_VALUE, buf,
464 				       sizeof(buf));
465 		if (ret < 0) {
466 			drm_err(intel_dp->aux.drm_dev,
467 				"[CONNECTOR:%d:%s] Failed to read Luminance from DPCD\n",
468 				connector->base.base.id, connector->base.name);
469 			return 0;
470 		}
471 
472 		val |= buf[0] | buf[1] << 8 | buf[2] << 16;
473 		return val / 1000;
474 	}
475 
476 	return connector->panel.backlight.level;
477 }
478 
479 static int
480 intel_dp_aux_vesa_set_luminance(struct intel_connector *connector, u32 level)
481 {
482 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
483 	u8 buf[3];
484 	int ret;
485 
486 	level = level * 1000;
487 	level &= 0xffffff;
488 	buf[0] = (level & 0x0000ff);
489 	buf[1] = (level & 0x00ff00) >> 8;
490 	buf[2] = (level & 0xff0000) >> 16;
491 
492 	ret = drm_dp_dpcd_write(&intel_dp->aux, DP_EDP_PANEL_TARGET_LUMINANCE_VALUE,
493 				buf, sizeof(buf));
494 	if (ret != sizeof(buf)) {
495 		drm_err(intel_dp->aux.drm_dev,
496 			"%s: Failed to set VESA Aux Luminance: %d\n",
497 			intel_dp->aux.name, ret);
498 		return -EINVAL;
499 	} else {
500 		return 0;
501 	}
502 }
503 
504 static void
505 intel_dp_aux_vesa_set_backlight(const struct drm_connector_state *conn_state, u32 level)
506 {
507 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
508 	struct intel_panel *panel = &connector->panel;
509 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
510 
511 	if (panel->backlight.edp.vesa.luminance_control_support) {
512 		if (!intel_dp_aux_vesa_set_luminance(connector, level))
513 			return;
514 	}
515 
516 	if (!panel->backlight.edp.vesa.info.aux_set) {
517 		const u32 pwm_level = intel_backlight_level_to_pwm(connector, level);
518 
519 		intel_backlight_set_pwm_level(conn_state, pwm_level);
520 	}
521 
522 	drm_edp_backlight_set_level(&intel_dp->aux, &panel->backlight.edp.vesa.info, level);
523 }
524 
525 static void
526 intel_dp_aux_vesa_enable_backlight(const struct intel_crtc_state *crtc_state,
527 				   const struct drm_connector_state *conn_state, u32 level)
528 {
529 	struct intel_connector *connector = to_intel_connector(conn_state->connector);
530 	struct intel_panel *panel = &connector->panel;
531 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
532 	int ret;
533 
534 	if (panel->backlight.edp.vesa.luminance_control_support) {
535 		ret = drm_dp_dpcd_writeb(&intel_dp->aux, DP_EDP_BACKLIGHT_MODE_SET_REGISTER,
536 					 DP_EDP_PANEL_LUMINANCE_CONTROL_ENABLE);
537 
538 		if (ret == 1)
539 			return;
540 
541 		if (!intel_dp_aux_vesa_set_luminance(connector, level))
542 			return;
543 	}
544 
545 	if (!panel->backlight.edp.vesa.info.aux_enable) {
546 		u32 pwm_level;
547 
548 		if (!panel->backlight.edp.vesa.info.aux_set)
549 			pwm_level = intel_backlight_level_to_pwm(connector, level);
550 		else
551 			pwm_level = intel_backlight_invert_pwm_level(connector,
552 								     panel->backlight.pwm_level_max);
553 
554 		panel->backlight.pwm_funcs->enable(crtc_state, conn_state, pwm_level);
555 	}
556 
557 	drm_edp_backlight_enable(&intel_dp->aux, &panel->backlight.edp.vesa.info, level);
558 }
559 
560 static void intel_dp_aux_vesa_disable_backlight(const struct drm_connector_state *old_conn_state,
561 						u32 level)
562 {
563 	struct intel_connector *connector = to_intel_connector(old_conn_state->connector);
564 	struct intel_panel *panel = &connector->panel;
565 	struct intel_dp *intel_dp = enc_to_intel_dp(connector->encoder);
566 
567 	if (panel->backlight.edp.vesa.luminance_control_support)
568 		return;
569 
570 	drm_edp_backlight_disable(&intel_dp->aux, &panel->backlight.edp.vesa.info);
571 
572 	if (!panel->backlight.edp.vesa.info.aux_enable)
573 		panel->backlight.pwm_funcs->disable(old_conn_state,
574 						    intel_backlight_invert_pwm_level(connector, 0));
575 }
576 
577 static int intel_dp_aux_vesa_setup_backlight(struct intel_connector *connector, enum pipe pipe)
578 {
579 	struct intel_display *display = to_intel_display(connector);
580 	struct drm_luminance_range_info *luminance_range =
581 		&connector->base.display_info.luminance_range;
582 	struct intel_dp *intel_dp = intel_attached_dp(connector);
583 	struct intel_panel *panel = &connector->panel;
584 	u16 current_level;
585 	u8 current_mode;
586 	int ret;
587 
588 	if (panel->backlight.edp.vesa.luminance_control_support) {
589 		if (luminance_range->max_luminance) {
590 			panel->backlight.max = luminance_range->max_luminance;
591 			panel->backlight.min = luminance_range->min_luminance;
592 		} else {
593 			panel->backlight.max = 512;
594 			panel->backlight.min = 0;
595 		}
596 		panel->backlight.level = intel_dp_aux_vesa_get_backlight(connector, 0);
597 		panel->backlight.enabled = panel->backlight.level != 0;
598 		drm_dbg_kms(display->drm,
599 			    "[CONNECTOR:%d:%s] AUX VESA Nits backlight level is controlled through DPCD\n",
600 			    connector->base.base.id, connector->base.name);
601 	} else {
602 		ret = drm_edp_backlight_init(&intel_dp->aux, &panel->backlight.edp.vesa.info,
603 					     panel->vbt.backlight.pwm_freq_hz, intel_dp->edp_dpcd,
604 					     &current_level, &current_mode);
605 		if (ret < 0)
606 			return ret;
607 
608 		drm_dbg_kms(display->drm,
609 			    "[CONNECTOR:%d:%s] AUX VESA backlight enable is controlled through %s\n",
610 			    connector->base.base.id, connector->base.name,
611 			    dpcd_vs_pwm_str(panel->backlight.edp.vesa.info.aux_enable));
612 		drm_dbg_kms(display->drm,
613 			    "[CONNECTOR:%d:%s] AUX VESA backlight level is controlled through %s\n",
614 			    connector->base.base.id, connector->base.name,
615 			    dpcd_vs_pwm_str(panel->backlight.edp.vesa.info.aux_set));
616 
617 		if (!panel->backlight.edp.vesa.info.aux_set ||
618 		    !panel->backlight.edp.vesa.info.aux_enable) {
619 			ret = panel->backlight.pwm_funcs->setup(connector, pipe);
620 			if (ret < 0) {
621 				drm_err(display->drm,
622 					"[CONNECTOR:%d:%s] Failed to setup PWM backlight controls for eDP backlight: %d\n",
623 					connector->base.base.id, connector->base.name, ret);
624 				return ret;
625 			}
626 		}
627 
628 		if (panel->backlight.edp.vesa.info.aux_set) {
629 			panel->backlight.max = panel->backlight.edp.vesa.info.max;
630 			panel->backlight.min = 0;
631 			if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_DPCD) {
632 				panel->backlight.level = current_level;
633 				panel->backlight.enabled = panel->backlight.level != 0;
634 			} else {
635 				panel->backlight.level = panel->backlight.max;
636 				panel->backlight.enabled = false;
637 			}
638 		} else {
639 			panel->backlight.max = panel->backlight.pwm_level_max;
640 			panel->backlight.min = panel->backlight.pwm_level_min;
641 			if (current_mode == DP_EDP_BACKLIGHT_CONTROL_MODE_PWM) {
642 				panel->backlight.level =
643 					panel->backlight.pwm_funcs->get(connector, pipe);
644 				panel->backlight.enabled = panel->backlight.pwm_enabled;
645 			} else {
646 				panel->backlight.level = panel->backlight.max;
647 				panel->backlight.enabled = false;
648 			}
649 		}
650 	}
651 
652 	drm_dbg_kms(display->drm,
653 		    "[CONNECTOR:%d:%s] Using AUX VESA interface for backlight control\n",
654 		    connector->base.base.id, connector->base.name);
655 
656 	return 0;
657 }
658 
659 static bool
660 intel_dp_aux_supports_vesa_backlight(struct intel_connector *connector)
661 {
662 	struct intel_display *display = to_intel_display(connector);
663 	struct intel_dp *intel_dp = intel_attached_dp(connector);
664 	struct intel_panel *panel = &connector->panel;
665 
666 	if ((intel_dp->edp_dpcd[3] & DP_EDP_PANEL_LUMINANCE_CONTROL_CAPABLE)) {
667 		drm_dbg_kms(display->drm,
668 			    "[CONNECTOR:%d:%s] AUX Luminance Based Backlight Control Supported!\n",
669 			    connector->base.base.id, connector->base.name);
670 		panel->backlight.edp.vesa.luminance_control_support = true;
671 		return true;
672 	}
673 
674 	if (drm_edp_backlight_supported(intel_dp->edp_dpcd)) {
675 		drm_dbg_kms(display->drm,
676 			    "[CONNECTOR:%d:%s] AUX Backlight Control Supported!\n",
677 			    connector->base.base.id, connector->base.name);
678 		return true;
679 	}
680 	return false;
681 }
682 
683 static const struct intel_panel_bl_funcs intel_dp_hdr_bl_funcs = {
684 	.setup = intel_dp_aux_hdr_setup_backlight,
685 	.enable = intel_dp_aux_hdr_enable_backlight,
686 	.disable = intel_dp_aux_hdr_disable_backlight,
687 	.set = intel_dp_aux_hdr_set_backlight,
688 	.get = intel_dp_aux_hdr_get_backlight,
689 };
690 
691 static const struct intel_panel_bl_funcs intel_dp_vesa_bl_funcs = {
692 	.setup = intel_dp_aux_vesa_setup_backlight,
693 	.enable = intel_dp_aux_vesa_enable_backlight,
694 	.disable = intel_dp_aux_vesa_disable_backlight,
695 	.set = intel_dp_aux_vesa_set_backlight,
696 	.get = intel_dp_aux_vesa_get_backlight,
697 };
698 
699 int intel_dp_aux_init_backlight_funcs(struct intel_connector *connector)
700 {
701 	struct intel_display *display = to_intel_display(connector);
702 	struct intel_dp *intel_dp = intel_attached_dp(connector);
703 	struct drm_device *dev = connector->base.dev;
704 	struct intel_panel *panel = &connector->panel;
705 	bool try_intel_interface = false, try_vesa_interface = false;
706 
707 	/* Check the VBT and user's module parameters to figure out which
708 	 * interfaces to probe
709 	 */
710 	switch (display->params.enable_dpcd_backlight) {
711 	case INTEL_DP_AUX_BACKLIGHT_OFF:
712 		return -ENODEV;
713 	case INTEL_DP_AUX_BACKLIGHT_AUTO:
714 		switch (panel->vbt.backlight.type) {
715 		case INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE:
716 			try_vesa_interface = true;
717 			break;
718 		case INTEL_BACKLIGHT_DISPLAY_DDI:
719 			try_intel_interface = true;
720 			break;
721 		default:
722 			return -ENODEV;
723 		}
724 		break;
725 	case INTEL_DP_AUX_BACKLIGHT_ON:
726 		if (panel->vbt.backlight.type != INTEL_BACKLIGHT_VESA_EDP_AUX_INTERFACE)
727 			try_intel_interface = true;
728 
729 		try_vesa_interface = true;
730 		break;
731 	case INTEL_DP_AUX_BACKLIGHT_FORCE_VESA:
732 		try_vesa_interface = true;
733 		break;
734 	case INTEL_DP_AUX_BACKLIGHT_FORCE_INTEL:
735 		try_intel_interface = true;
736 		break;
737 	}
738 
739 	/* For eDP 1.5 and above we are supposed to use VESA interface for brightness control */
740 	if (intel_dp->edp_dpcd[0] >= DP_EDP_15)
741 		try_vesa_interface = true;
742 
743 	/*
744 	 * Since Intel has their own backlight control interface, the majority of machines out there
745 	 * using DPCD backlight controls with Intel GPUs will be using this interface as opposed to
746 	 * the VESA interface. However, other GPUs (such as Nvidia's) will always use the VESA
747 	 * interface. This means that there's quite a number of panels out there that will advertise
748 	 * support for both interfaces, primarily systems with Intel/Nvidia hybrid GPU setups.
749 	 *
750 	 * There's a catch to this though: on many panels that advertise support for both
751 	 * interfaces, the VESA backlight interface will stop working once we've programmed the
752 	 * panel with Intel's OUI - which is also required for us to be able to detect Intel's
753 	 * backlight interface at all. This means that the only sensible way for us to detect both
754 	 * interfaces is to probe for Intel's first, and VESA's second.
755 	 */
756 	if (try_intel_interface && intel_dp_aux_supports_hdr_backlight(connector) &&
757 	    intel_dp->edp_dpcd[0] <= DP_EDP_14b) {
758 		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using Intel proprietary eDP backlight controls\n",
759 			    connector->base.base.id, connector->base.name);
760 		panel->backlight.funcs = &intel_dp_hdr_bl_funcs;
761 		return 0;
762 	}
763 
764 	if (try_vesa_interface && intel_dp_aux_supports_vesa_backlight(connector)) {
765 		drm_dbg_kms(dev, "[CONNECTOR:%d:%s] Using VESA eDP backlight controls\n",
766 			    connector->base.base.id, connector->base.name);
767 		panel->backlight.funcs = &intel_dp_vesa_bl_funcs;
768 		return 0;
769 	}
770 
771 	return -ENODEV;
772 }
773