xref: /dragonfly/sys/dev/drm/i915/intel_color.c (revision de5eb4c5)
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 = dev->dev_private;
100 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
101 	int i, pipe = intel_crtc->pipe;
102 	uint16_t coeffs[9] = { 0, };
103 
104 	if (crtc_state->ctm) {
105 		struct drm_color_ctm *ctm =
106 			(struct drm_color_ctm *)crtc_state->ctm->data;
107 		uint64_t input[9] = { 0, };
108 
109 		if (intel_crtc->config->limited_color_range) {
110 			ctm_mult_by_limited(input, (int64_t *)ctm->matrix);
111 		} else {
112 			for (i = 0; i < ARRAY_SIZE(input); i++)
113 				input[i] = ctm->matrix[i];
114 		}
115 
116 		/*
117 		 * Convert fixed point S31.32 input to format supported by the
118 		 * hardware.
119 		 */
120 		for (i = 0; i < ARRAY_SIZE(coeffs); i++) {
121 			uint64_t abs_coeff = ((1ULL << 63) - 1) & input[i];
122 
123 			/*
124 			 * Clamp input value to min/max supported by
125 			 * hardware.
126 			 */
127 			abs_coeff = clamp_val(abs_coeff, 0, CTM_COEFF_4_0 - 1);
128 
129 			/* sign bit */
130 			if (CTM_COEFF_NEGATIVE(input[i]))
131 				coeffs[i] |= 1 << 15;
132 
133 			if (abs_coeff < CTM_COEFF_0_125)
134 				coeffs[i] |= (3 << 12) |
135 					I9XX_CSC_COEFF_FP(abs_coeff, 12);
136 			else if (abs_coeff < CTM_COEFF_0_25)
137 				coeffs[i] |= (2 << 12) |
138 					I9XX_CSC_COEFF_FP(abs_coeff, 11);
139 			else if (abs_coeff < CTM_COEFF_0_5)
140 				coeffs[i] |= (1 << 12) |
141 					I9XX_CSC_COEFF_FP(abs_coeff, 10);
142 			else if (abs_coeff < CTM_COEFF_1_0)
143 				coeffs[i] |= I9XX_CSC_COEFF_FP(abs_coeff, 9);
144 			else if (abs_coeff < CTM_COEFF_2_0)
145 				coeffs[i] |= (7 << 12) |
146 					I9XX_CSC_COEFF_FP(abs_coeff, 8);
147 			else
148 				coeffs[i] |= (6 << 12) |
149 					I9XX_CSC_COEFF_FP(abs_coeff, 7);
150 		}
151 	} else {
152 		/*
153 		 * Load an identity matrix if no coefficients are provided.
154 		 *
155 		 * TODO: Check what kind of values actually come out of the
156 		 * pipe with these coeff/postoff values and adjust to get the
157 		 * best accuracy. Perhaps we even need to take the bpc value
158 		 * into consideration.
159 		 */
160 		for (i = 0; i < 3; i++) {
161 			if (intel_crtc->config->limited_color_range)
162 				coeffs[i * 3 + i] =
163 					I9XX_CSC_COEFF_LIMITED_RANGE;
164 			else
165 				coeffs[i * 3 + i] = I9XX_CSC_COEFF_1_0;
166 		}
167 	}
168 
169 	I915_WRITE(PIPE_CSC_COEFF_RY_GY(pipe), coeffs[0] << 16 | coeffs[1]);
170 	I915_WRITE(PIPE_CSC_COEFF_BY(pipe), coeffs[2] << 16);
171 
172 	I915_WRITE(PIPE_CSC_COEFF_RU_GU(pipe), coeffs[3] << 16 | coeffs[4]);
173 	I915_WRITE(PIPE_CSC_COEFF_BU(pipe), coeffs[5] << 16);
174 
175 	I915_WRITE(PIPE_CSC_COEFF_RV_GV(pipe), coeffs[6] << 16 | coeffs[7]);
176 	I915_WRITE(PIPE_CSC_COEFF_BV(pipe), coeffs[8] << 16);
177 
178 	I915_WRITE(PIPE_CSC_PREOFF_HI(pipe), 0);
179 	I915_WRITE(PIPE_CSC_PREOFF_ME(pipe), 0);
180 	I915_WRITE(PIPE_CSC_PREOFF_LO(pipe), 0);
181 
182 	if (INTEL_INFO(dev)->gen > 6) {
183 		uint16_t postoff = 0;
184 
185 		if (intel_crtc->config->limited_color_range)
186 			postoff = (16 * (1 << 12) / 255) & 0x1fff;
187 
188 		I915_WRITE(PIPE_CSC_POSTOFF_HI(pipe), postoff);
189 		I915_WRITE(PIPE_CSC_POSTOFF_ME(pipe), postoff);
190 		I915_WRITE(PIPE_CSC_POSTOFF_LO(pipe), postoff);
191 
192 		I915_WRITE(PIPE_CSC_MODE(pipe), 0);
193 	} else {
194 		uint32_t mode = CSC_MODE_YUV_TO_RGB;
195 
196 		if (intel_crtc->config->limited_color_range)
197 			mode |= CSC_BLACK_SCREEN_OFFSET;
198 
199 		I915_WRITE(PIPE_CSC_MODE(pipe), mode);
200 	}
201 }
202 
203 /*
204  * Set up the pipe CSC unit on CherryView.
205  */
206 static void cherryview_load_csc_matrix(struct drm_crtc_state *state)
207 {
208 	struct drm_crtc *crtc = state->crtc;
209 	struct drm_device *dev = crtc->dev;
210 	struct drm_i915_private *dev_priv = dev->dev_private;
211 	int pipe = to_intel_crtc(crtc)->pipe;
212 	uint32_t mode;
213 
214 	if (state->ctm) {
215 		struct drm_color_ctm *ctm =
216 			(struct drm_color_ctm *) state->ctm->data;
217 		uint16_t coeffs[9] = { 0, };
218 		int i;
219 
220 		for (i = 0; i < ARRAY_SIZE(coeffs); i++) {
221 			uint64_t abs_coeff =
222 				((1ULL << 63) - 1) & ctm->matrix[i];
223 
224 			/* Round coefficient. */
225 			abs_coeff += 1 << (32 - 13);
226 			/* Clamp to hardware limits. */
227 			abs_coeff = clamp_val(abs_coeff, 0, CTM_COEFF_8_0 - 1);
228 
229 			/* Write coefficients in S3.12 format. */
230 			if (ctm->matrix[i] & (1ULL << 63))
231 				coeffs[i] = 1 << 15;
232 			coeffs[i] |= ((abs_coeff >> 32) & 7) << 12;
233 			coeffs[i] |= (abs_coeff >> 20) & 0xfff;
234 		}
235 
236 		I915_WRITE(CGM_PIPE_CSC_COEFF01(pipe),
237 			   coeffs[1] << 16 | coeffs[0]);
238 		I915_WRITE(CGM_PIPE_CSC_COEFF23(pipe),
239 			   coeffs[3] << 16 | coeffs[2]);
240 		I915_WRITE(CGM_PIPE_CSC_COEFF45(pipe),
241 			   coeffs[5] << 16 | coeffs[4]);
242 		I915_WRITE(CGM_PIPE_CSC_COEFF67(pipe),
243 			   coeffs[7] << 16 | coeffs[6]);
244 		I915_WRITE(CGM_PIPE_CSC_COEFF8(pipe), coeffs[8]);
245 	}
246 
247 	mode = (state->ctm ? CGM_PIPE_MODE_CSC : 0);
248 	if (!crtc_state_is_legacy(state)) {
249 		mode |= (state->degamma_lut ? CGM_PIPE_MODE_DEGAMMA : 0) |
250 			(state->gamma_lut ? CGM_PIPE_MODE_GAMMA : 0);
251 	}
252 	I915_WRITE(CGM_PIPE_MODE(pipe), mode);
253 }
254 
255 void intel_color_set_csc(struct drm_crtc_state *crtc_state)
256 {
257 	struct drm_device *dev = crtc_state->crtc->dev;
258 	struct drm_i915_private *dev_priv = dev->dev_private;
259 
260 	if (dev_priv->display.load_csc_matrix)
261 		dev_priv->display.load_csc_matrix(crtc_state);
262 }
263 
264 /* Loads the legacy palette/gamma unit for the CRTC. */
265 static void i9xx_load_luts_internal(struct drm_crtc *crtc,
266 				    struct drm_property_blob *blob)
267 {
268 	struct drm_device *dev = crtc->dev;
269 	struct drm_i915_private *dev_priv = dev->dev_private;
270 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
271 	enum i915_pipe pipe = intel_crtc->pipe;
272 	int i;
273 
274 	if (HAS_GMCH_DISPLAY(dev)) {
275 		if (intel_crtc->config->has_dsi_encoder)
276 			assert_dsi_pll_enabled(dev_priv);
277 		else
278 			assert_pll_enabled(dev_priv, pipe);
279 	}
280 
281 	if (blob) {
282 		struct drm_color_lut *lut = (struct drm_color_lut *) blob->data;
283 		for (i = 0; i < 256; i++) {
284 			uint32_t word =
285 				(drm_color_lut_extract(lut[i].red, 8) << 16) |
286 				(drm_color_lut_extract(lut[i].green, 8) << 8) |
287 				drm_color_lut_extract(lut[i].blue, 8);
288 
289 			if (HAS_GMCH_DISPLAY(dev))
290 				I915_WRITE(PALETTE(pipe, i), word);
291 			else
292 				I915_WRITE(LGC_PALETTE(pipe, i), word);
293 		}
294 	} else {
295 		for (i = 0; i < 256; i++) {
296 			uint32_t word = (i << 16) | (i << 8) | i;
297 
298 			if (HAS_GMCH_DISPLAY(dev))
299 				I915_WRITE(PALETTE(pipe, i), word);
300 			else
301 				I915_WRITE(LGC_PALETTE(pipe, i), word);
302 		}
303 	}
304 }
305 
306 static void i9xx_load_luts(struct drm_crtc_state *crtc_state)
307 {
308 	i9xx_load_luts_internal(crtc_state->crtc, crtc_state->gamma_lut);
309 }
310 
311 /* Loads the legacy palette/gamma unit for the CRTC on Haswell. */
312 static void haswell_load_luts(struct drm_crtc_state *crtc_state)
313 {
314 	struct drm_crtc *crtc = crtc_state->crtc;
315 	struct drm_device *dev = crtc->dev;
316 	struct drm_i915_private *dev_priv = dev->dev_private;
317 	struct intel_crtc *intel_crtc = to_intel_crtc(crtc);
318 	struct intel_crtc_state *intel_crtc_state =
319 		to_intel_crtc_state(crtc_state);
320 	bool reenable_ips = false;
321 
322 	/*
323 	 * Workaround : Do not read or write the pipe palette/gamma data while
324 	 * GAMMA_MODE is configured for split gamma and IPS_CTL has IPS enabled.
325 	 */
326 	if (IS_HASWELL(dev) && intel_crtc->config->ips_enabled &&
327 	    (intel_crtc_state->gamma_mode == GAMMA_MODE_MODE_SPLIT)) {
328 		hsw_disable_ips(intel_crtc);
329 		reenable_ips = true;
330 	}
331 
332 	intel_crtc_state->gamma_mode = GAMMA_MODE_MODE_8BIT;
333 	I915_WRITE(GAMMA_MODE(intel_crtc->pipe), GAMMA_MODE_MODE_8BIT);
334 
335 	i9xx_load_luts(crtc_state);
336 
337 	if (reenable_ips)
338 		hsw_enable_ips(intel_crtc);
339 }
340 
341 /* Loads the palette/gamma unit for the CRTC on Broadwell+. */
342 static void broadwell_load_luts(struct drm_crtc_state *state)
343 {
344 	struct drm_crtc *crtc = state->crtc;
345 	struct drm_device *dev = crtc->dev;
346 	struct drm_i915_private *dev_priv = dev->dev_private;
347 	struct intel_crtc_state *intel_state = to_intel_crtc_state(state);
348 	enum i915_pipe pipe = to_intel_crtc(crtc)->pipe;
349 	uint32_t i, lut_size = INTEL_INFO(dev)->color.degamma_lut_size;
350 
351 	if (crtc_state_is_legacy(state)) {
352 		haswell_load_luts(state);
353 		return;
354 	}
355 
356 	I915_WRITE(PREC_PAL_INDEX(pipe),
357 		   PAL_PREC_SPLIT_MODE | PAL_PREC_AUTO_INCREMENT);
358 
359 	if (state->degamma_lut) {
360 		struct drm_color_lut *lut =
361 			(struct drm_color_lut *) state->degamma_lut->data;
362 
363 		for (i = 0; i < lut_size; i++) {
364 			uint32_t word =
365 			drm_color_lut_extract(lut[i].red, 10) << 20 |
366 			drm_color_lut_extract(lut[i].green, 10) << 10 |
367 			drm_color_lut_extract(lut[i].blue, 10);
368 
369 			I915_WRITE(PREC_PAL_DATA(pipe), word);
370 		}
371 	} else {
372 		for (i = 0; i < lut_size; i++) {
373 			uint32_t v = (i * ((1 << 10) - 1)) / (lut_size - 1);
374 
375 			I915_WRITE(PREC_PAL_DATA(pipe),
376 				   (v << 20) | (v << 10) | v);
377 		}
378 	}
379 
380 	if (state->gamma_lut) {
381 		struct drm_color_lut *lut =
382 			(struct drm_color_lut *) state->gamma_lut->data;
383 
384 		for (i = 0; i < lut_size; i++) {
385 			uint32_t word =
386 			(drm_color_lut_extract(lut[i].red, 10) << 20) |
387 			(drm_color_lut_extract(lut[i].green, 10) << 10) |
388 			drm_color_lut_extract(lut[i].blue, 10);
389 
390 			I915_WRITE(PREC_PAL_DATA(pipe), word);
391 		}
392 
393 		/* Program the max register to clamp values > 1.0. */
394 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 0),
395 			   drm_color_lut_extract(lut[i].red, 16));
396 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 1),
397 			   drm_color_lut_extract(lut[i].green, 16));
398 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 2),
399 			   drm_color_lut_extract(lut[i].blue, 16));
400 	} else {
401 		for (i = 0; i < lut_size; i++) {
402 			uint32_t v = (i * ((1 << 10) - 1)) / (lut_size - 1);
403 
404 			I915_WRITE(PREC_PAL_DATA(pipe),
405 				   (v << 20) | (v << 10) | v);
406 		}
407 
408 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 0), (1 << 16) - 1);
409 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 1), (1 << 16) - 1);
410 		I915_WRITE(PREC_PAL_GC_MAX(pipe, 2), (1 << 16) - 1);
411 	}
412 
413 	intel_state->gamma_mode = GAMMA_MODE_MODE_SPLIT;
414 	I915_WRITE(GAMMA_MODE(pipe), GAMMA_MODE_MODE_SPLIT);
415 	POSTING_READ(GAMMA_MODE(pipe));
416 
417 	/*
418 	 * Reset the index, otherwise it prevents the legacy palette to be
419 	 * written properly.
420 	 */
421 	I915_WRITE(PREC_PAL_INDEX(pipe), 0);
422 }
423 
424 /* Loads the palette/gamma unit for the CRTC on CherryView. */
425 static void cherryview_load_luts(struct drm_crtc_state *state)
426 {
427 	struct drm_crtc *crtc = state->crtc;
428 	struct drm_device *dev = crtc->dev;
429 	struct drm_i915_private *dev_priv = dev->dev_private;
430 	enum i915_pipe pipe = to_intel_crtc(crtc)->pipe;
431 	struct drm_color_lut *lut;
432 	uint32_t i, lut_size;
433 	uint32_t word0, word1;
434 
435 	if (crtc_state_is_legacy(state)) {
436 		/* Turn off degamma/gamma on CGM block. */
437 		I915_WRITE(CGM_PIPE_MODE(pipe),
438 			   (state->ctm ? CGM_PIPE_MODE_CSC : 0));
439 		i9xx_load_luts_internal(crtc, state->gamma_lut);
440 		return;
441 	}
442 
443 	if (state->degamma_lut) {
444 		lut = (struct drm_color_lut *) state->degamma_lut->data;
445 		lut_size = INTEL_INFO(dev)->color.degamma_lut_size;
446 		for (i = 0; i < lut_size; i++) {
447 			/* Write LUT in U0.14 format. */
448 			word0 =
449 			(drm_color_lut_extract(lut[i].green, 14) << 16) |
450 			drm_color_lut_extract(lut[i].blue, 14);
451 			word1 = drm_color_lut_extract(lut[i].red, 14);
452 
453 			I915_WRITE(CGM_PIPE_DEGAMMA(pipe, i, 0), word0);
454 			I915_WRITE(CGM_PIPE_DEGAMMA(pipe, i, 1), word1);
455 		}
456 	}
457 
458 	if (state->gamma_lut) {
459 		lut = (struct drm_color_lut *) state->gamma_lut->data;
460 		lut_size = INTEL_INFO(dev)->color.gamma_lut_size;
461 		for (i = 0; i < lut_size; i++) {
462 			/* Write LUT in U0.10 format. */
463 			word0 =
464 			(drm_color_lut_extract(lut[i].green, 10) << 16) |
465 			drm_color_lut_extract(lut[i].blue, 10);
466 			word1 = drm_color_lut_extract(lut[i].red, 10);
467 
468 			I915_WRITE(CGM_PIPE_GAMMA(pipe, i, 0), word0);
469 			I915_WRITE(CGM_PIPE_GAMMA(pipe, i, 1), word1);
470 		}
471 	}
472 
473 	I915_WRITE(CGM_PIPE_MODE(pipe),
474 		   (state->ctm ? CGM_PIPE_MODE_CSC : 0) |
475 		   (state->degamma_lut ? CGM_PIPE_MODE_DEGAMMA : 0) |
476 		   (state->gamma_lut ? CGM_PIPE_MODE_GAMMA : 0));
477 
478 	/*
479 	 * Also program a linear LUT in the legacy block (behind the
480 	 * CGM block).
481 	 */
482 	i9xx_load_luts_internal(crtc, NULL);
483 }
484 
485 void intel_color_load_luts(struct drm_crtc_state *crtc_state)
486 {
487 	struct drm_device *dev = crtc_state->crtc->dev;
488 	struct drm_i915_private *dev_priv = dev->dev_private;
489 
490 	dev_priv->display.load_luts(crtc_state);
491 }
492 
493 int intel_color_check(struct drm_crtc *crtc,
494 		      struct drm_crtc_state *crtc_state)
495 {
496 	struct drm_device *dev = crtc->dev;
497 	size_t gamma_length, degamma_length;
498 
499 	degamma_length = INTEL_INFO(dev)->color.degamma_lut_size *
500 		sizeof(struct drm_color_lut);
501 	gamma_length = INTEL_INFO(dev)->color.gamma_lut_size *
502 		sizeof(struct drm_color_lut);
503 
504 	/*
505 	 * We allow both degamma & gamma luts at the right size or
506 	 * NULL.
507 	 */
508 	if ((!crtc_state->degamma_lut ||
509 	     crtc_state->degamma_lut->length == degamma_length) &&
510 	    (!crtc_state->gamma_lut ||
511 	     crtc_state->gamma_lut->length == gamma_length))
512 		return 0;
513 
514 	/*
515 	 * We also allow no degamma lut and a gamma lut at the legacy
516 	 * size (256 entries).
517 	 */
518 	if (!crtc_state->degamma_lut &&
519 	    crtc_state->gamma_lut &&
520 	    crtc_state->gamma_lut->length == LEGACY_LUT_LENGTH)
521 		return 0;
522 
523 	return -EINVAL;
524 }
525 
526 void intel_color_init(struct drm_crtc *crtc)
527 {
528 	struct drm_device *dev = crtc->dev;
529 	struct drm_i915_private *dev_priv = dev->dev_private;
530 
531 	drm_mode_crtc_set_gamma_size(crtc, 256);
532 
533 	if (IS_CHERRYVIEW(dev)) {
534 		dev_priv->display.load_csc_matrix = cherryview_load_csc_matrix;
535 		dev_priv->display.load_luts = cherryview_load_luts;
536 	} else if (IS_HASWELL(dev)) {
537 		dev_priv->display.load_csc_matrix = i9xx_load_csc_matrix;
538 		dev_priv->display.load_luts = haswell_load_luts;
539 	} else if (IS_BROADWELL(dev) || IS_SKYLAKE(dev) ||
540 		   IS_BROXTON(dev) || IS_KABYLAKE(dev)) {
541 		dev_priv->display.load_csc_matrix = i9xx_load_csc_matrix;
542 		dev_priv->display.load_luts = broadwell_load_luts;
543 	} else {
544 		dev_priv->display.load_luts = i9xx_load_luts;
545 	}
546 
547 	/* Enable color management support when we have degamma & gamma LUTs. */
548 	if (INTEL_INFO(dev)->color.degamma_lut_size != 0 &&
549 	    INTEL_INFO(dev)->color.gamma_lut_size != 0)
550 		drm_helper_crtc_enable_color_mgmt(crtc,
551 					INTEL_INFO(dev)->color.degamma_lut_size,
552 					INTEL_INFO(dev)->color.gamma_lut_size);
553 }
554