1 /*
2  * Copyright 2018 Advanced Micro Devices, Inc.
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 shall be included in
12  * all copies or substantial portions of the Software.
13  *
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.
21  *
22  * Authors: AMD
23  *
24  */
25 #include "amdgpu.h"
26 #include "amdgpu_mode.h"
27 #include "amdgpu_dm.h"
28 #include "dc.h"
29 #include "modules/color/color_gamma.h"
30 #include "basics/conversion.h"
31 
32 /**
33  * DOC: overview
34  *
35  * The DC interface to HW gives us the following color management blocks
36  * per pipe (surface):
37  *
38  * - Input gamma LUT (de-normalized)
39  * - Input CSC (normalized)
40  * - Surface degamma LUT (normalized)
41  * - Surface CSC (normalized)
42  * - Surface regamma LUT (normalized)
43  * - Output CSC (normalized)
44  *
45  * But these aren't a direct mapping to DRM color properties. The current DRM
46  * interface exposes CRTC degamma, CRTC CTM and CRTC regamma while our hardware
47  * is essentially giving:
48  *
49  * Plane CTM -> Plane degamma -> Plane CTM -> Plane regamma -> Plane CTM
50  *
51  * The input gamma LUT block isn't really applicable here since it operates
52  * on the actual input data itself rather than the HW fp representation. The
53  * input and output CSC blocks are technically available to use as part of
54  * the DC interface but are typically used internally by DC for conversions
55  * between color spaces. These could be blended together with user
56  * adjustments in the future but for now these should remain untouched.
57  *
58  * The pipe blending also happens after these blocks so we don't actually
59  * support any CRTC props with correct blending with multiple planes - but we
60  * can still support CRTC color management properties in DM in most single
61  * plane cases correctly with clever management of the DC interface in DM.
62  *
63  * As per DRM documentation, blocks should be in hardware bypass when their
64  * respective property is set to NULL. A linear DGM/RGM LUT should also
65  * considered as putting the respective block into bypass mode.
66  *
67  * This means that the following
68  * configuration is assumed to be the default:
69  *
70  * Plane DGM Bypass -> Plane CTM Bypass -> Plane RGM Bypass -> ...
71  * CRTC DGM Bypass -> CRTC CTM Bypass -> CRTC RGM Bypass
72  */
73 
74 #define MAX_DRM_LUT_VALUE 0xFFFF
75 
76 /**
77  * amdgpu_dm_init_color_mod - Initialize the color module.
78  *
79  * We're not using the full color module, only certain components.
80  * Only call setup functions for components that we need.
81  */
amdgpu_dm_init_color_mod(void)82 void amdgpu_dm_init_color_mod(void)
83 {
84 	setup_x_points_distribution();
85 }
86 
87 /**
88  * __extract_blob_lut - Extracts the DRM lut and lut size from a blob.
89  * @blob: DRM color mgmt property blob
90  * @size: lut size
91  *
92  * Returns:
93  * DRM LUT or NULL
94  */
95 static const struct drm_color_lut *
__extract_blob_lut(const struct drm_property_blob * blob,uint32_t * size)96 __extract_blob_lut(const struct drm_property_blob *blob, uint32_t *size)
97 {
98 	*size = blob ? drm_color_lut_size(blob) : 0;
99 	return blob ? (struct drm_color_lut *)blob->data : NULL;
100 }
101 
102 /**
103  * __is_lut_linear - check if the given lut is a linear mapping of values
104  * @lut: given lut to check values
105  * @size: lut size
106  *
107  * It is considered linear if the lut represents:
108  * f(a) = (0xFF00/MAX_COLOR_LUT_ENTRIES-1)a; for integer a in [0,
109  * MAX_COLOR_LUT_ENTRIES)
110  *
111  * Returns:
112  * True if the given lut is a linear mapping of values, i.e. it acts like a
113  * bypass LUT. Otherwise, false.
114  */
__is_lut_linear(const struct drm_color_lut * lut,uint32_t size)115 static bool __is_lut_linear(const struct drm_color_lut *lut, uint32_t size)
116 {
117 	int i;
118 	uint32_t expected;
119 	int delta;
120 
121 	for (i = 0; i < size; i++) {
122 		/* All color values should equal */
123 		if ((lut[i].red != lut[i].green) || (lut[i].green != lut[i].blue))
124 			return false;
125 
126 		expected = i * MAX_DRM_LUT_VALUE / (size-1);
127 
128 		/* Allow a +/-1 error. */
129 		delta = lut[i].red - expected;
130 		if (delta < -1 || 1 < delta)
131 			return false;
132 	}
133 	return true;
134 }
135 
136 /**
137  * __drm_lut_to_dc_gamma - convert the drm_color_lut to dc_gamma.
138  * @lut: DRM lookup table for color conversion
139  * @gamma: DC gamma to set entries
140  * @is_legacy: legacy or atomic gamma
141  *
142  * The conversion depends on the size of the lut - whether or not it's legacy.
143  */
__drm_lut_to_dc_gamma(const struct drm_color_lut * lut,struct dc_gamma * gamma,bool is_legacy)144 static void __drm_lut_to_dc_gamma(const struct drm_color_lut *lut,
145 				  struct dc_gamma *gamma, bool is_legacy)
146 {
147 	uint32_t r, g, b;
148 	int i;
149 
150 	if (is_legacy) {
151 		for (i = 0; i < MAX_COLOR_LEGACY_LUT_ENTRIES; i++) {
152 			r = drm_color_lut_extract(lut[i].red, 16);
153 			g = drm_color_lut_extract(lut[i].green, 16);
154 			b = drm_color_lut_extract(lut[i].blue, 16);
155 
156 			gamma->entries.red[i] = dc_fixpt_from_int(r);
157 			gamma->entries.green[i] = dc_fixpt_from_int(g);
158 			gamma->entries.blue[i] = dc_fixpt_from_int(b);
159 		}
160 		return;
161 	}
162 
163 	/* else */
164 	for (i = 0; i < MAX_COLOR_LUT_ENTRIES; i++) {
165 		r = drm_color_lut_extract(lut[i].red, 16);
166 		g = drm_color_lut_extract(lut[i].green, 16);
167 		b = drm_color_lut_extract(lut[i].blue, 16);
168 
169 		gamma->entries.red[i] = dc_fixpt_from_fraction(r, MAX_DRM_LUT_VALUE);
170 		gamma->entries.green[i] = dc_fixpt_from_fraction(g, MAX_DRM_LUT_VALUE);
171 		gamma->entries.blue[i] = dc_fixpt_from_fraction(b, MAX_DRM_LUT_VALUE);
172 	}
173 }
174 
175 /**
176  * __drm_ctm_to_dc_matrix - converts a DRM CTM to a DC CSC float matrix
177  * @ctm: DRM color transformation matrix
178  * @matrix: DC CSC float matrix
179  *
180  * The matrix needs to be a 3x4 (12 entry) matrix.
181  */
__drm_ctm_to_dc_matrix(const struct drm_color_ctm * ctm,struct fixed31_32 * matrix)182 static void __drm_ctm_to_dc_matrix(const struct drm_color_ctm *ctm,
183 				   struct fixed31_32 *matrix)
184 {
185 	int64_t val;
186 	int i;
187 
188 	/*
189 	 * DRM gives a 3x3 matrix, but DC wants 3x4. Assuming we're operating
190 	 * with homogeneous coordinates, augment the matrix with 0's.
191 	 *
192 	 * The format provided is S31.32, using signed-magnitude representation.
193 	 * Our fixed31_32 is also S31.32, but is using 2's complement. We have
194 	 * to convert from signed-magnitude to 2's complement.
195 	 */
196 	for (i = 0; i < 12; i++) {
197 		/* Skip 4th element */
198 		if (i % 4 == 3) {
199 			matrix[i] = dc_fixpt_zero;
200 			continue;
201 		}
202 
203 		/* gamut_remap_matrix[i] = ctm[i - floor(i/4)] */
204 		val = ctm->matrix[i - (i / 4)];
205 		/* If negative, convert to 2's complement. */
206 		if (val & (1ULL << 63))
207 			val = -(val & ~(1ULL << 63));
208 
209 		matrix[i].value = val;
210 	}
211 }
212 
213 /**
214  * __set_legacy_tf - Calculates the legacy transfer function
215  * @func: transfer function
216  * @lut: lookup table that defines the color space
217  * @lut_size: size of respective lut
218  * @has_rom: if ROM can be used for hardcoded curve
219  *
220  * Only for sRGB input space
221  *
222  * Returns:
223  * 0 in case of success, -ENOMEM if fails
224  */
__set_legacy_tf(struct dc_transfer_func * func,const struct drm_color_lut * lut,uint32_t lut_size,bool has_rom)225 static int __set_legacy_tf(struct dc_transfer_func *func,
226 			   const struct drm_color_lut *lut, uint32_t lut_size,
227 			   bool has_rom)
228 {
229 	struct dc_gamma *gamma = NULL;
230 	struct calculate_buffer cal_buffer = {0};
231 	bool res;
232 
233 	ASSERT(lut && lut_size == MAX_COLOR_LEGACY_LUT_ENTRIES);
234 
235 	cal_buffer.buffer_index = -1;
236 
237 	gamma = dc_create_gamma();
238 	if (!gamma)
239 		return -ENOMEM;
240 
241 	gamma->type = GAMMA_RGB_256;
242 	gamma->num_entries = lut_size;
243 	__drm_lut_to_dc_gamma(lut, gamma, true);
244 
245 	res = mod_color_calculate_regamma_params(func, gamma, true, has_rom,
246 						 NULL, &cal_buffer);
247 
248 	dc_gamma_release(&gamma);
249 
250 	return res ? 0 : -ENOMEM;
251 }
252 
253 /**
254  * __set_output_tf - calculates the output transfer function based on expected input space.
255  * @func: transfer function
256  * @lut: lookup table that defines the color space
257  * @lut_size: size of respective lut
258  * @has_rom: if ROM can be used for hardcoded curve
259  *
260  * Returns:
261  * 0 in case of success. -ENOMEM if fails.
262  */
__set_output_tf(struct dc_transfer_func * func,const struct drm_color_lut * lut,uint32_t lut_size,bool has_rom)263 static int __set_output_tf(struct dc_transfer_func *func,
264 			   const struct drm_color_lut *lut, uint32_t lut_size,
265 			   bool has_rom)
266 {
267 	struct dc_gamma *gamma = NULL;
268 	struct calculate_buffer cal_buffer = {0};
269 	bool res;
270 
271 	ASSERT(lut && lut_size == MAX_COLOR_LUT_ENTRIES);
272 
273 	cal_buffer.buffer_index = -1;
274 
275 	gamma = dc_create_gamma();
276 	if (!gamma)
277 		return -ENOMEM;
278 
279 	gamma->num_entries = lut_size;
280 	__drm_lut_to_dc_gamma(lut, gamma, false);
281 
282 	if (func->tf == TRANSFER_FUNCTION_LINEAR) {
283 		/*
284 		 * Color module doesn't like calculating regamma params
285 		 * on top of a linear input. But degamma params can be used
286 		 * instead to simulate this.
287 		 */
288 		gamma->type = GAMMA_CUSTOM;
289 		res = mod_color_calculate_degamma_params(NULL, func,
290 							gamma, true);
291 	} else {
292 		/*
293 		 * Assume sRGB. The actual mapping will depend on whether the
294 		 * input was legacy or not.
295 		 */
296 		gamma->type = GAMMA_CS_TFM_1D;
297 		res = mod_color_calculate_regamma_params(func, gamma, false,
298 							 has_rom, NULL, &cal_buffer);
299 	}
300 
301 	dc_gamma_release(&gamma);
302 
303 	return res ? 0 : -ENOMEM;
304 }
305 
306 /**
307  * __set_input_tf - calculates the input transfer function based on expected
308  * input space.
309  * @func: transfer function
310  * @lut: lookup table that defines the color space
311  * @lut_size: size of respective lut.
312  *
313  * Returns:
314  * 0 in case of success. -ENOMEM if fails.
315  */
__set_input_tf(struct dc_transfer_func * func,const struct drm_color_lut * lut,uint32_t lut_size)316 static int __set_input_tf(struct dc_transfer_func *func,
317 			  const struct drm_color_lut *lut, uint32_t lut_size)
318 {
319 	struct dc_gamma *gamma = NULL;
320 	bool res;
321 
322 	gamma = dc_create_gamma();
323 	if (!gamma)
324 		return -ENOMEM;
325 
326 	gamma->type = GAMMA_CUSTOM;
327 	gamma->num_entries = lut_size;
328 
329 	__drm_lut_to_dc_gamma(lut, gamma, false);
330 
331 	res = mod_color_calculate_degamma_params(NULL, func, gamma, true);
332 	dc_gamma_release(&gamma);
333 
334 	return res ? 0 : -ENOMEM;
335 }
336 
337 /**
338  * amdgpu_dm_verify_lut_sizes - verifies if DRM luts match the hw supported sizes
339  * @crtc_state: the DRM CRTC state
340  *
341  * Verifies that the Degamma and Gamma LUTs attached to the &crtc_state
342  * are of the expected size.
343  *
344  * Returns:
345  * 0 on success. -EINVAL if any lut sizes are invalid.
346  */
amdgpu_dm_verify_lut_sizes(const struct drm_crtc_state * crtc_state)347 int amdgpu_dm_verify_lut_sizes(const struct drm_crtc_state *crtc_state)
348 {
349 	const struct drm_color_lut *lut = NULL;
350 	uint32_t size = 0;
351 
352 	lut = __extract_blob_lut(crtc_state->degamma_lut, &size);
353 	if (lut && size != MAX_COLOR_LUT_ENTRIES) {
354 		DRM_DEBUG_DRIVER(
355 			"Invalid Degamma LUT size. Should be %u but got %u.\n",
356 			MAX_COLOR_LUT_ENTRIES, size);
357 		return -EINVAL;
358 	}
359 
360 	lut = __extract_blob_lut(crtc_state->gamma_lut, &size);
361 	if (lut && size != MAX_COLOR_LUT_ENTRIES &&
362 	    size != MAX_COLOR_LEGACY_LUT_ENTRIES) {
363 		DRM_DEBUG_DRIVER(
364 			"Invalid Gamma LUT size. Should be %u (or %u for legacy) but got %u.\n",
365 			MAX_COLOR_LUT_ENTRIES, MAX_COLOR_LEGACY_LUT_ENTRIES,
366 			size);
367 		return -EINVAL;
368 	}
369 
370 	return 0;
371 }
372 
373 /**
374  * amdgpu_dm_update_crtc_color_mgmt: Maps DRM color management to DC stream.
375  * @crtc: amdgpu_dm crtc state
376  *
377  * With no plane level color management properties we're free to use any
378  * of the HW blocks as long as the CRTC CTM always comes before the
379  * CRTC RGM and after the CRTC DGM.
380  *
381  * - The CRTC RGM block will be placed in the RGM LUT block if it is non-linear.
382  * - The CRTC DGM block will be placed in the DGM LUT block if it is non-linear.
383  * - The CRTC CTM will be placed in the gamut remap block if it is non-linear.
384  *
385  * The RGM block is typically more fully featured and accurate across
386  * all ASICs - DCE can't support a custom non-linear CRTC DGM.
387  *
388  * For supporting both plane level color management and CRTC level color
389  * management at once we have to either restrict the usage of CRTC properties
390  * or blend adjustments together.
391  *
392  * Returns:
393  * 0 on success. Error code if setup fails.
394  */
amdgpu_dm_update_crtc_color_mgmt(struct dm_crtc_state * crtc)395 int amdgpu_dm_update_crtc_color_mgmt(struct dm_crtc_state *crtc)
396 {
397 	struct dc_stream_state *stream = crtc->stream;
398 	struct amdgpu_device *adev = drm_to_adev(crtc->base.state->dev);
399 	bool has_rom = adev->asic_type <= CHIP_RAVEN;
400 	struct drm_color_ctm *ctm = NULL;
401 	const struct drm_color_lut *degamma_lut, *regamma_lut;
402 	uint32_t degamma_size, regamma_size;
403 	bool has_regamma, has_degamma;
404 	bool is_legacy;
405 	int r;
406 
407 	r = amdgpu_dm_verify_lut_sizes(&crtc->base);
408 	if (r)
409 		return r;
410 
411 	degamma_lut = __extract_blob_lut(crtc->base.degamma_lut, &degamma_size);
412 	regamma_lut = __extract_blob_lut(crtc->base.gamma_lut, &regamma_size);
413 
414 	has_degamma =
415 		degamma_lut && !__is_lut_linear(degamma_lut, degamma_size);
416 
417 	has_regamma =
418 		regamma_lut && !__is_lut_linear(regamma_lut, regamma_size);
419 
420 	is_legacy = regamma_size == MAX_COLOR_LEGACY_LUT_ENTRIES;
421 
422 	/* Reset all adjustments. */
423 	crtc->cm_has_degamma = false;
424 	crtc->cm_is_degamma_srgb = false;
425 
426 	/* Setup regamma and degamma. */
427 	if (is_legacy) {
428 		/*
429 		 * Legacy regamma forces us to use the sRGB RGM as a base.
430 		 * This also means we can't use linear DGM since DGM needs
431 		 * to use sRGB as a base as well, resulting in incorrect CRTC
432 		 * DGM and CRTC CTM.
433 		 *
434 		 * TODO: Just map this to the standard regamma interface
435 		 * instead since this isn't really right. One of the cases
436 		 * where this setup currently fails is trying to do an
437 		 * inverse color ramp in legacy userspace.
438 		 */
439 		crtc->cm_is_degamma_srgb = true;
440 		stream->out_transfer_func->type = TF_TYPE_DISTRIBUTED_POINTS;
441 		stream->out_transfer_func->tf = TRANSFER_FUNCTION_SRGB;
442 
443 		r = __set_legacy_tf(stream->out_transfer_func, regamma_lut,
444 				    regamma_size, has_rom);
445 		if (r)
446 			return r;
447 	} else if (has_regamma) {
448 		/* If atomic regamma, CRTC RGM goes into RGM LUT. */
449 		stream->out_transfer_func->type = TF_TYPE_DISTRIBUTED_POINTS;
450 		stream->out_transfer_func->tf = TRANSFER_FUNCTION_LINEAR;
451 
452 		r = __set_output_tf(stream->out_transfer_func, regamma_lut,
453 				    regamma_size, has_rom);
454 		if (r)
455 			return r;
456 	} else {
457 		/*
458 		 * No CRTC RGM means we can just put the block into bypass
459 		 * since we don't have any plane level adjustments using it.
460 		 */
461 		stream->out_transfer_func->type = TF_TYPE_BYPASS;
462 		stream->out_transfer_func->tf = TRANSFER_FUNCTION_LINEAR;
463 	}
464 
465 	/*
466 	 * CRTC DGM goes into DGM LUT. It would be nice to place it
467 	 * into the RGM since it's a more featured block but we'd
468 	 * have to place the CTM in the OCSC in that case.
469 	 */
470 	crtc->cm_has_degamma = has_degamma;
471 
472 	/* Setup CRTC CTM. */
473 	if (crtc->base.ctm) {
474 		ctm = (struct drm_color_ctm *)crtc->base.ctm->data;
475 
476 		/*
477 		 * Gamut remapping must be used for gamma correction
478 		 * since it comes before the regamma correction.
479 		 *
480 		 * OCSC could be used for gamma correction, but we'd need to
481 		 * blend the adjustments together with the required output
482 		 * conversion matrix - so just use the gamut remap block
483 		 * for now.
484 		 */
485 		__drm_ctm_to_dc_matrix(ctm, stream->gamut_remap_matrix.matrix);
486 
487 		stream->gamut_remap_matrix.enable_remap = true;
488 		stream->csc_color_matrix.enable_adjustment = false;
489 	} else {
490 		/* Bypass CTM. */
491 		stream->gamut_remap_matrix.enable_remap = false;
492 		stream->csc_color_matrix.enable_adjustment = false;
493 	}
494 
495 	return 0;
496 }
497 
498 /**
499  * amdgpu_dm_update_plane_color_mgmt: Maps DRM color management to DC plane.
500  * @crtc: amdgpu_dm crtc state
501  * @dc_plane_state: target DC surface
502  *
503  * Update the underlying dc_stream_state's input transfer function (ITF) in
504  * preparation for hardware commit. The transfer function used depends on
505  * the preparation done on the stream for color management.
506  *
507  * Returns:
508  * 0 on success. -ENOMEM if mem allocation fails.
509  */
amdgpu_dm_update_plane_color_mgmt(struct dm_crtc_state * crtc,struct dc_plane_state * dc_plane_state)510 int amdgpu_dm_update_plane_color_mgmt(struct dm_crtc_state *crtc,
511 				      struct dc_plane_state *dc_plane_state)
512 {
513 	const struct drm_color_lut *degamma_lut;
514 	enum dc_transfer_func_predefined tf = TRANSFER_FUNCTION_SRGB;
515 	uint32_t degamma_size;
516 	int r;
517 
518 	/* Get the correct base transfer function for implicit degamma. */
519 	switch (dc_plane_state->format) {
520 	case SURFACE_PIXEL_FORMAT_VIDEO_420_YCbCr:
521 	case SURFACE_PIXEL_FORMAT_VIDEO_420_YCrCb:
522 		/* DC doesn't have a transfer function for BT601 specifically. */
523 		tf = TRANSFER_FUNCTION_BT709;
524 		break;
525 	default:
526 		break;
527 	}
528 
529 	if (crtc->cm_has_degamma) {
530 		degamma_lut = __extract_blob_lut(crtc->base.degamma_lut,
531 						 &degamma_size);
532 		ASSERT(degamma_size == MAX_COLOR_LUT_ENTRIES);
533 
534 		dc_plane_state->in_transfer_func->type =
535 			TF_TYPE_DISTRIBUTED_POINTS;
536 
537 		/*
538 		 * This case isn't fully correct, but also fairly
539 		 * uncommon. This is userspace trying to use a
540 		 * legacy gamma LUT + atomic degamma LUT
541 		 * at the same time.
542 		 *
543 		 * Legacy gamma requires the input to be in linear
544 		 * space, so that means we need to apply an sRGB
545 		 * degamma. But color module also doesn't support
546 		 * a user ramp in this case so the degamma will
547 		 * be lost.
548 		 *
549 		 * Even if we did support it, it's still not right:
550 		 *
551 		 * Input -> CRTC DGM -> sRGB DGM -> CRTC CTM ->
552 		 * sRGB RGM -> CRTC RGM -> Output
553 		 *
554 		 * The CSC will be done in the wrong space since
555 		 * we're applying an sRGB DGM on top of the CRTC
556 		 * DGM.
557 		 *
558 		 * TODO: Don't use the legacy gamma interface and just
559 		 * map these to the atomic one instead.
560 		 */
561 		if (crtc->cm_is_degamma_srgb)
562 			dc_plane_state->in_transfer_func->tf = tf;
563 		else
564 			dc_plane_state->in_transfer_func->tf =
565 				TRANSFER_FUNCTION_LINEAR;
566 
567 		r = __set_input_tf(dc_plane_state->in_transfer_func,
568 				   degamma_lut, degamma_size);
569 		if (r)
570 			return r;
571 	} else if (crtc->cm_is_degamma_srgb) {
572 		/*
573 		 * For legacy gamma support we need the regamma input
574 		 * in linear space. Assume that the input is sRGB.
575 		 */
576 		dc_plane_state->in_transfer_func->type = TF_TYPE_PREDEFINED;
577 		dc_plane_state->in_transfer_func->tf = tf;
578 
579 		if (tf != TRANSFER_FUNCTION_SRGB &&
580 		    !mod_color_calculate_degamma_params(NULL,
581 			    dc_plane_state->in_transfer_func, NULL, false))
582 			return -ENOMEM;
583 	} else {
584 		/* ...Otherwise we can just bypass the DGM block. */
585 		dc_plane_state->in_transfer_func->type = TF_TYPE_BYPASS;
586 		dc_plane_state->in_transfer_func->tf = TRANSFER_FUNCTION_LINEAR;
587 	}
588 
589 	return 0;
590 }
591