xref: /dragonfly/sys/dev/drm/i915/intel_color.c (revision e89cf083)
1 /*
2  * Copyright © 2016 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
21  * DEALINGS IN THE SOFTWARE.
22  *
23  */
24 
25 #include "intel_drv.h"
26 
27 #define CTM_COEFF_SIGN	(1ULL << 63)
28 
29 #define CTM_COEFF_1_0	(1ULL << 32)
30 #define CTM_COEFF_2_0	(CTM_COEFF_1_0 << 1)
31 #define CTM_COEFF_4_0	(CTM_COEFF_2_0 << 1)
32 #define CTM_COEFF_8_0	(CTM_COEFF_4_0 << 1)
33 #define CTM_COEFF_0_5	(CTM_COEFF_1_0 >> 1)
34 #define CTM_COEFF_0_25	(CTM_COEFF_0_5 >> 1)
35 #define CTM_COEFF_0_125	(CTM_COEFF_0_25 >> 1)
36 
37 #define CTM_COEFF_LIMITED_RANGE ((235ULL - 16ULL) * CTM_COEFF_1_0 / 255)
38 
39 #define CTM_COEFF_NEGATIVE(coeff)	(((coeff) & CTM_COEFF_SIGN) != 0)
40 #define CTM_COEFF_ABS(coeff)		((coeff) & (CTM_COEFF_SIGN - 1))
41 
42 #define LEGACY_LUT_LENGTH		(sizeof(struct drm_color_lut) * 256)
43 
44 /*
45  * Extract the CSC coefficient from a CTM coefficient (in U32.32 fixed point
46  * format). This macro takes the coefficient we want transformed and the
47  * number of fractional bits.
48  *
49  * We only have a 9 bits precision window which slides depending on the value
50  * of the CTM coefficient and we write the value from bit 3. We also round the
51  * value.
52  */
53 #define I9XX_CSC_COEFF_FP(coeff, fbits)	\
54 	(clamp_val(((coeff) >> (32 - (fbits) - 3)) + 4, 0, 0xfff) & 0xff8)
55 
56 #define I9XX_CSC_COEFF_LIMITED_RANGE	\
57 	I9XX_CSC_COEFF_FP(CTM_COEFF_LIMITED_RANGE, 9)
58 #define I9XX_CSC_COEFF_1_0		\
59 	((7 << 12) | I9XX_CSC_COEFF_FP(CTM_COEFF_1_0, 8))
60 
61 static bool crtc_state_is_legacy(struct drm_crtc_state *state)
62 {
63 	return !state->degamma_lut &&
64 		!state->ctm &&
65 		state->gamma_lut &&
66 		state->gamma_lut->length == LEGACY_LUT_LENGTH;
67 }
68 
69 /*
70  * When using limited range, multiply the matrix given by userspace by
71  * the matrix that we would use for the limited range. We do the
72  * multiplication in U2.30 format.
73  */
74 static void ctm_mult_by_limited(uint64_t *result, int64_t *input)
75 {
76 	int i;
77 
78 	for (i = 0; i < 9; i++)
79 		result[i] = 0;
80 
81 	for (i = 0; i < 3; i++) {
82 		int64_t user_coeff = input[i * 3 + i];
83 		uint64_t limited_coeff = CTM_COEFF_LIMITED_RANGE >> 2;
84 		uint64_t abs_coeff = clamp_val(CTM_COEFF_ABS(user_coeff),
85 					       0,
86 					       CTM_COEFF_4_0 - 1) >> 2;
87 
88 		result[i * 3 + i] = (limited_coeff * abs_coeff) >> 27;
89 		if (CTM_COEFF_NEGATIVE(user_coeff))
90 			result[i * 3 + i] |= CTM_COEFF_SIGN;
91 	}
92 }
93 
94 /* Set up the pipe CSC unit. */
95 static void i9xx_load_csc_matrix(struct drm_crtc_state *crtc_state)
96 {
97 	struct drm_crtc *crtc = crtc_state->crtc;
98 	struct drm_device *dev = crtc->dev;
99 	struct drm_i915_private *dev_priv = to_i915(dev);
100 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
101 	int i, pipe = intel_crtc->pipe;
102 	uint16_t coeffs[9] = { 0, };
103 	struct intel_crtc_state *intel_crtc_state = to_intel_crtc_state(crtc_state);
104 
105 	if (crtc_state->ctm) {
106 		struct drm_color_ctm *ctm =
107 			(struct drm_color_ctm *)crtc_state->ctm->data;
108 		uint64_t input[9] = { 0, };
109 
110 		if (intel_crtc_state->limited_color_range) {
111 			ctm_mult_by_limited(input, (int64_t *)ctm->matrix);
112 		} else {
113 			for (i = 0; i < ARRAY_SIZE(input); i++)
114 				input[i] = ctm->matrix[i];
115 		}
116 
117 		/*
118 		 * Convert fixed point S31.32 input to format supported by the
119 		 * hardware.
120 		 */
121 		for (i = 0; i < ARRAY_SIZE(coeffs); i++) {
122 			uint64_t abs_coeff = ((1ULL << 63) - 1) & input[i];
123 
124 			/*
125 			 * Clamp input value to min/max supported by
126 			 * hardware.
127 			 */
128 			abs_coeff = clamp_val(abs_coeff, 0, CTM_COEFF_4_0 - 1);
129 
130 			/* sign bit */
131 			if (CTM_COEFF_NEGATIVE(input[i]))
132 				coeffs[i] |= 1 << 15;
133 
134 			if (abs_coeff < CTM_COEFF_0_125)
135 				coeffs[i] |= (3 << 12) |
136 					I9XX_CSC_COEFF_FP(abs_coeff, 12);
137 			else if (abs_coeff < CTM_COEFF_0_25)
138 				coeffs[i] |= (2 << 12) |
139 					I9XX_CSC_COEFF_FP(abs_coeff, 11);
140 			else if (abs_coeff < CTM_COEFF_0_5)
141 				coeffs[i] |= (1 << 12) |
142 					I9XX_CSC_COEFF_FP(abs_coeff, 10);
143 			else if (abs_coeff < CTM_COEFF_1_0)
144 				coeffs[i] |= I9XX_CSC_COEFF_FP(abs_coeff, 9);
145 			else if (abs_coeff < CTM_COEFF_2_0)
146 				coeffs[i] |= (7 << 12) |
147 					I9XX_CSC_COEFF_FP(abs_coeff, 8);
148 			else
149 				coeffs[i] |= (6 << 12) |
150 					I9XX_CSC_COEFF_FP(abs_coeff, 7);
151 		}
152 	} else {
153 		/*
154 		 * Load an identity matrix if no coefficients are provided.
155 		 *
156 		 * TODO: Check what kind of values actually come out of the
157 		 * pipe with these coeff/postoff values and adjust to get the
158 		 * best accuracy. Perhaps we even need to take the bpc value
159 		 * into consideration.
160 		 */
161 		for (i = 0; i < 3; i++) {
162 			if (intel_crtc_state->limited_color_range)
163 				coeffs[i * 3 + i] =
164 					I9XX_CSC_COEFF_LIMITED_RANGE;
165 			else
166 				coeffs[i * 3 + i] = I9XX_CSC_COEFF_1_0;
167 		}
168 	}
169 
170 	I915_WRITE(PIPE_CSC_COEFF_RY_GY(pipe), coeffs[0] << 16 | coeffs[1]);
171 	I915_WRITE(PIPE_CSC_COEFF_BY(pipe), coeffs[2] << 16);
172 
173 	I915_WRITE(PIPE_CSC_COEFF_RU_GU(pipe), coeffs[3] << 16 | coeffs[4]);
174 	I915_WRITE(PIPE_CSC_COEFF_BU(pipe), coeffs[5] << 16);
175 
176 	I915_WRITE(PIPE_CSC_COEFF_RV_GV(pipe), coeffs[6] << 16 | coeffs[7]);
177 	I915_WRITE(PIPE_CSC_COEFF_BV(pipe), coeffs[8] << 16);
178 
179 	I915_WRITE(PIPE_CSC_PREOFF_HI(pipe), 0);
180 	I915_WRITE(PIPE_CSC_PREOFF_ME(pipe), 0);
181 	I915_WRITE(PIPE_CSC_PREOFF_LO(pipe), 0);
182 
183 	if (INTEL_INFO(dev)->gen > 6) {
184 		uint16_t postoff = 0;
185 
186 		if (intel_crtc_state->limited_color_range)
187 			postoff = (16 * (1 << 12) / 255) & 0x1fff;
188 
189 		I915_WRITE(PIPE_CSC_POSTOFF_HI(pipe), postoff);
190 		I915_WRITE(PIPE_CSC_POSTOFF_ME(pipe), postoff);
191 		I915_WRITE(PIPE_CSC_POSTOFF_LO(pipe), postoff);
192 
193 		I915_WRITE(PIPE_CSC_MODE(pipe), 0);
194 	} else {
195 		uint32_t mode = CSC_MODE_YUV_TO_RGB;
196 
197 		if (intel_crtc_state->limited_color_range)
198 			mode |= CSC_BLACK_SCREEN_OFFSET;
199 
200 		I915_WRITE(PIPE_CSC_MODE(pipe), mode);
201 	}
202 }
203 
204 /*
205  * Set up the pipe CSC unit on CherryView.
206  */
207 static void cherryview_load_csc_matrix(struct drm_crtc_state *state)
208 {
209 	struct drm_crtc *crtc = state->crtc;
210 	struct drm_device *dev = crtc->dev;
211 	struct drm_i915_private *dev_priv = to_i915(dev);
212 	int pipe = to_intel_crtc(crtc)->pipe;
213 	uint32_t mode;
214 
215 	if (state->ctm) {
216 		struct drm_color_ctm *ctm =
217 			(struct drm_color_ctm *) state->ctm->data;
218 		uint16_t coeffs[9] = { 0, };
219 		int i;
220 
221 		for (i = 0; i < ARRAY_SIZE(coeffs); i++) {
222 			uint64_t abs_coeff =
223 				((1ULL << 63) - 1) & ctm->matrix[i];
224 
225 			/* Round coefficient. */
226 			abs_coeff += 1 << (32 - 13);
227 			/* Clamp to hardware limits. */
228 			abs_coeff = clamp_val(abs_coeff, 0, CTM_COEFF_8_0 - 1);
229 
230 			/* Write coefficients in S3.12 format. */
231 			if (ctm->matrix[i] & (1ULL << 63))
232 				coeffs[i] = 1 << 15;
233 			coeffs[i] |= ((abs_coeff >> 32) & 7) << 12;
234 			coeffs[i] |= (abs_coeff >> 20) & 0xfff;
235 		}
236 
237 		I915_WRITE(CGM_PIPE_CSC_COEFF01(pipe),
238 			   coeffs[1] << 16 | coeffs[0]);
239 		I915_WRITE(CGM_PIPE_CSC_COEFF23(pipe),
240 			   coeffs[3] << 16 | coeffs[2]);
241 		I915_WRITE(CGM_PIPE_CSC_COEFF45(pipe),
242 			   coeffs[5] << 16 | coeffs[4]);
243 		I915_WRITE(CGM_PIPE_CSC_COEFF67(pipe),
244 			   coeffs[7] << 16 | coeffs[6]);
245 		I915_WRITE(CGM_PIPE_CSC_COEFF8(pipe), coeffs[8]);
246 	}
247 
248 	mode = (state->ctm ? CGM_PIPE_MODE_CSC : 0);
249 	if (!crtc_state_is_legacy(state)) {
250 		mode |= (state->degamma_lut ? CGM_PIPE_MODE_DEGAMMA : 0) |
251 			(state->gamma_lut ? CGM_PIPE_MODE_GAMMA : 0);
252 	}
253 	I915_WRITE(CGM_PIPE_MODE(pipe), mode);
254 }
255 
256 void intel_color_set_csc(struct drm_crtc_state *crtc_state)
257 {
258 	struct drm_device *dev = crtc_state->crtc->dev;
259 	struct drm_i915_private *dev_priv = to_i915(dev);
260 
261 	if (dev_priv->display.load_csc_matrix)
262 		dev_priv->display.load_csc_matrix(crtc_state);
263 }
264 
265 /* Loads the legacy palette/gamma unit for the CRTC. */
266 static void i9xx_load_luts_internal(struct drm_crtc *crtc,
267 				    struct drm_property_blob *blob,
268 				    struct intel_crtc_state *crtc_state)
269 {
270 	struct drm_device *dev = crtc->dev;
271 	struct drm_i915_private *dev_priv = to_i915(dev);
272 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
273 	enum i915_pipe pipe = intel_crtc->pipe;
274 	int i;
275 
276 	if (HAS_GMCH_DISPLAY(dev_priv)) {
277 		if (intel_crtc_has_type(crtc_state, INTEL_OUTPUT_DSI))
278 			assert_dsi_pll_enabled(dev_priv);
279 		else
280 			assert_pll_enabled(dev_priv, pipe);
281 	}
282 
283 	if (blob) {
284 		struct drm_color_lut *lut = (struct drm_color_lut *) blob->data;
285 		for (i = 0; i < 256; i++) {
286 			uint32_t word =
287 				(drm_color_lut_extract(lut[i].red, 8) << 16) |
288 				(drm_color_lut_extract(lut[i].green, 8) << 8) |
289 				drm_color_lut_extract(lut[i].blue, 8);
290 
291 			if (HAS_GMCH_DISPLAY(dev_priv))
292 				I915_WRITE(PALETTE(pipe, i), word);
293 			else
294 				I915_WRITE(LGC_PALETTE(pipe, i), word);
295 		}
296 	} else {
297 		for (i = 0; i < 256; i++) {
298 			uint32_t word = (i << 16) | (i << 8) | i;
299 
300 			if (HAS_GMCH_DISPLAY(dev_priv))
301 				I915_WRITE(PALETTE(pipe, i), word);
302 			else
303 				I915_WRITE(LGC_PALETTE(pipe, i), word);
304 		}
305 	}
306 }
307 
308 static void i9xx_load_luts(struct drm_crtc_state *crtc_state)
309 {
310 	i9xx_load_luts_internal(crtc_state->crtc, crtc_state->gamma_lut,
311 				to_intel_crtc_state(crtc_state));
312 }
313 
314 /* Loads the legacy palette/gamma unit for the CRTC on Haswell. */
315 static void haswell_load_luts(struct drm_crtc_state *crtc_state)
316 {
317 	struct drm_crtc *crtc = crtc_state->crtc;
318 	struct drm_device *dev = crtc->dev;
319 	struct drm_i915_private *dev_priv = to_i915(dev);
320 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
321 	struct intel_crtc_state *intel_crtc_state =
322 		to_intel_crtc_state(crtc_state);
323 	bool reenable_ips = false;
324 
325 	/*
326 	 * Workaround : Do not read or write the pipe palette/gamma data while
327 	 * GAMMA_MODE is configured for split gamma and IPS_CTL has IPS enabled.
328 	 */
329 	if (IS_HASWELL(dev_priv) && intel_crtc_state->ips_enabled &&
330 	    (intel_crtc_state->gamma_mode == GAMMA_MODE_MODE_SPLIT)) {
331 		hsw_disable_ips(intel_crtc);
332 		reenable_ips = true;
333 	}
334 
335 	intel_crtc_state->gamma_mode = GAMMA_MODE_MODE_8BIT;
336 	I915_WRITE(GAMMA_MODE(intel_crtc->pipe), GAMMA_MODE_MODE_8BIT);
337 
338 	i9xx_load_luts(crtc_state);
339 
340 	if (reenable_ips)
341 		hsw_enable_ips(intel_crtc);
342 }
343 
344 /* Loads the palette/gamma unit for the CRTC on Broadwell+. */
345 static void broadwell_load_luts(struct drm_crtc_state *state)
346 {
347 	struct drm_crtc *crtc = state->crtc;
348 	struct drm_device *dev = crtc->dev;
349 	struct drm_i915_private *dev_priv = to_i915(dev);
350 	struct intel_crtc_state *intel_state = to_intel_crtc_state(state);
351 	enum i915_pipe pipe = to_intel_crtc(crtc)->pipe;
352 	uint32_t i, lut_size = INTEL_INFO(dev)->color.degamma_lut_size;
353 
354 	if (crtc_state_is_legacy(state)) {
355 		haswell_load_luts(state);
356 		return;
357 	}
358 
359 	I915_WRITE(PREC_PAL_INDEX(pipe),
360 		   PAL_PREC_SPLIT_MODE | PAL_PREC_AUTO_INCREMENT);
361 
362 	if (state->degamma_lut) {
363 		struct drm_color_lut *lut =
364 			(struct drm_color_lut *) state->degamma_lut->data;
365 
366 		for (i = 0; i < lut_size; i++) {
367 			uint32_t word =
368 			drm_color_lut_extract(lut[i].red, 10) << 20 |
369 			drm_color_lut_extract(lut[i].green, 10) << 10 |
370 			drm_color_lut_extract(lut[i].blue, 10);
371 
372 			I915_WRITE(PREC_PAL_DATA(pipe), word);
373 		}
374 	} else {
375 		for (i = 0; i < lut_size; i++) {
376 			uint32_t v = (i * ((1 << 10) - 1)) / (lut_size - 1);
377 
378 			I915_WRITE(PREC_PAL_DATA(pipe),
379 				   (v << 20) | (v << 10) | v);
380 		}
381 	}
382 
383 	if (state->gamma_lut) {
384 		struct drm_color_lut *lut =
385 			(struct drm_color_lut *) state->gamma_lut->data;
386 
387 		for (i = 0; i < lut_size; i++) {
388 			uint32_t word =
389 			(drm_color_lut_extract(lut[i].red, 10) << 20) |
390 			(drm_color_lut_extract(lut[i].green, 10) << 10) |
391 			drm_color_lut_extract(lut[i].blue, 10);
392 
393 			I915_WRITE(PREC_PAL_DATA(pipe), word);
394 		}
395 
396 		/* Program the max register to clamp values > 1.0. */
397 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 0),
398 			   drm_color_lut_extract(lut[i].red, 16));
399 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 1),
400 			   drm_color_lut_extract(lut[i].green, 16));
401 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 2),
402 			   drm_color_lut_extract(lut[i].blue, 16));
403 	} else {
404 		for (i = 0; i < lut_size; i++) {
405 			uint32_t v = (i * ((1 << 10) - 1)) / (lut_size - 1);
406 
407 			I915_WRITE(PREC_PAL_DATA(pipe),
408 				   (v << 20) | (v << 10) | v);
409 		}
410 
411 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 0), (1 << 16) - 1);
412 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 1), (1 << 16) - 1);
413 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 2), (1 << 16) - 1);
414 	}
415 
416 	intel_state->gamma_mode = GAMMA_MODE_MODE_SPLIT;
417 	I915_WRITE(GAMMA_MODE(pipe), GAMMA_MODE_MODE_SPLIT);
418 	POSTING_READ(GAMMA_MODE(pipe));
419 
420 	/*
421 	 * Reset the index, otherwise it prevents the legacy palette to be
422 	 * written properly.
423 	 */
424 	I915_WRITE(PREC_PAL_INDEX(pipe), 0);
425 }
426 
427 /* Loads the palette/gamma unit for the CRTC on CherryView. */
428 static void cherryview_load_luts(struct drm_crtc_state *state)
429 {
430 	struct drm_crtc *crtc = state->crtc;
431 	struct drm_device *dev = crtc->dev;
432 	struct drm_i915_private *dev_priv = to_i915(dev);
433 	enum i915_pipe pipe = to_intel_crtc(crtc)->pipe;
434 	struct drm_color_lut *lut;
435 	uint32_t i, lut_size;
436 	uint32_t word0, word1;
437 
438 	if (crtc_state_is_legacy(state)) {
439 		/* Turn off degamma/gamma on CGM block. */
440 		I915_WRITE(CGM_PIPE_MODE(pipe),
441 			   (state->ctm ? CGM_PIPE_MODE_CSC : 0));
442 		i9xx_load_luts_internal(crtc, state->gamma_lut,
443 					to_intel_crtc_state(state));
444 		return;
445 	}
446 
447 	if (state->degamma_lut) {
448 		lut = (struct drm_color_lut *) state->degamma_lut->data;
449 		lut_size = INTEL_INFO(dev)->color.degamma_lut_size;
450 		for (i = 0; i < lut_size; i++) {
451 			/* Write LUT in U0.14 format. */
452 			word0 =
453 			(drm_color_lut_extract(lut[i].green, 14) << 16) |
454 			drm_color_lut_extract(lut[i].blue, 14);
455 			word1 = drm_color_lut_extract(lut[i].red, 14);
456 
457 			I915_WRITE(CGM_PIPE_DEGAMMA(pipe, i, 0), word0);
458 			I915_WRITE(CGM_PIPE_DEGAMMA(pipe, i, 1), word1);
459 		}
460 	}
461 
462 	if (state->gamma_lut) {
463 		lut = (struct drm_color_lut *) state->gamma_lut->data;
464 		lut_size = INTEL_INFO(dev)->color.gamma_lut_size;
465 		for (i = 0; i < lut_size; i++) {
466 			/* Write LUT in U0.10 format. */
467 			word0 =
468 			(drm_color_lut_extract(lut[i].green, 10) << 16) |
469 			drm_color_lut_extract(lut[i].blue, 10);
470 			word1 = drm_color_lut_extract(lut[i].red, 10);
471 
472 			I915_WRITE(CGM_PIPE_GAMMA(pipe, i, 0), word0);
473 			I915_WRITE(CGM_PIPE_GAMMA(pipe, i, 1), word1);
474 		}
475 	}
476 
477 	I915_WRITE(CGM_PIPE_MODE(pipe),
478 		   (state->ctm ? CGM_PIPE_MODE_CSC : 0) |
479 		   (state->degamma_lut ? CGM_PIPE_MODE_DEGAMMA : 0) |
480 		   (state->gamma_lut ? CGM_PIPE_MODE_GAMMA : 0));
481 
482 	/*
483 	 * Also program a linear LUT in the legacy block (behind the
484 	 * CGM block).
485 	 */
486 	i9xx_load_luts_internal(crtc, NULL, to_intel_crtc_state(state));
487 }
488 
489 void intel_color_load_luts(struct drm_crtc_state *crtc_state)
490 {
491 	struct drm_device *dev = crtc_state->crtc->dev;
492 	struct drm_i915_private *dev_priv = to_i915(dev);
493 
494 	dev_priv->display.load_luts(crtc_state);
495 }
496 
497 int intel_color_check(struct drm_crtc *crtc,
498 		      struct drm_crtc_state *crtc_state)
499 {
500 	struct drm_device *dev = crtc->dev;
501 	size_t gamma_length, degamma_length;
502 
503 	degamma_length = INTEL_INFO(dev)->color.degamma_lut_size *
504 		sizeof(struct drm_color_lut);
505 	gamma_length = INTEL_INFO(dev)->color.gamma_lut_size *
506 		sizeof(struct drm_color_lut);
507 
508 	/*
509 	 * We allow both degamma & gamma luts at the right size or
510 	 * NULL.
511 	 */
512 	if ((!crtc_state->degamma_lut ||
513 	     crtc_state->degamma_lut->length == degamma_length) &&
514 	    (!crtc_state->gamma_lut ||
515 	     crtc_state->gamma_lut->length == gamma_length))
516 		return 0;
517 
518 	/*
519 	 * We also allow no degamma lut and a gamma lut at the legacy
520 	 * size (256 entries).
521 	 */
522 	if (!crtc_state->degamma_lut &&
523 	    crtc_state->gamma_lut &&
524 	    crtc_state->gamma_lut->length == LEGACY_LUT_LENGTH)
525 		return 0;
526 
527 	return -EINVAL;
528 }
529 
530 void intel_color_init(struct drm_crtc *crtc)
531 {
532 	struct drm_device *dev = crtc->dev;
533 	struct drm_i915_private *dev_priv = to_i915(dev);
534 
535 	drm_mode_crtc_set_gamma_size(crtc, 256);
536 
537 	if (IS_CHERRYVIEW(dev_priv)) {
538 		dev_priv->display.load_csc_matrix = cherryview_load_csc_matrix;
539 		dev_priv->display.load_luts = cherryview_load_luts;
540 	} else if (IS_HASWELL(dev_priv)) {
541 		dev_priv->display.load_csc_matrix = i9xx_load_csc_matrix;
542 		dev_priv->display.load_luts = haswell_load_luts;
543 	} else if (IS_BROADWELL(dev_priv) || IS_SKYLAKE(dev_priv) ||
544 		   IS_BROXTON(dev_priv) || IS_KABYLAKE(dev_priv)) {
545 		dev_priv->display.load_csc_matrix = i9xx_load_csc_matrix;
546 		dev_priv->display.load_luts = broadwell_load_luts;
547 	} else {
548 		dev_priv->display.load_luts = i9xx_load_luts;
549 	}
550 
551 	/* Enable color management support when we have degamma & gamma LUTs. */
552 	if (INTEL_INFO(dev)->color.degamma_lut_size != 0 &&
553 	    INTEL_INFO(dev)->color.gamma_lut_size != 0)
554 		drm_crtc_enable_color_mgmt(crtc,
555 					INTEL_INFO(dev)->color.degamma_lut_size,
556 					true,
557 					INTEL_INFO(dev)->color.gamma_lut_size);
558 }
559