xref: /linux/drivers/gpu/drm/amd/display/dc/link/link_validation.c (revision 269c1d1443d6686595ac187c247973014a1ee709)
1 /*
2  * Copyright 2023 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 
26 /* FILE POLICY AND INTENDED USAGE:
27  * This file owns timing validation against various link limitations. (ex.
28  * link bandwidth, receiver capability or our hardware capability) It also
29  * provides helper functions exposing bandwidth formulas used in validation.
30  */
31 #include "link_validation.h"
32 #include "protocols/link_dp_capability.h"
33 #include "protocols/link_dp_dpia_bw.h"
34 #include "resource.h"
35 
36 #define DC_LOGGER_INIT(logger)
37 
38 static uint32_t get_tmds_output_pixel_clock_100hz(const struct dc_crtc_timing *timing)
39 {
40 
41 	uint32_t pxl_clk = timing->pix_clk_100hz;
42 
43 	if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR420)
44 		pxl_clk /= 2;
45 	else if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR422)
46 		pxl_clk = pxl_clk * 2 / 3;
47 
48 	if (timing->display_color_depth == COLOR_DEPTH_101010)
49 		pxl_clk = pxl_clk * 10 / 8;
50 	else if (timing->display_color_depth == COLOR_DEPTH_121212)
51 		pxl_clk = pxl_clk * 12 / 8;
52 
53 	return pxl_clk;
54 }
55 
56 static bool dp_active_dongle_validate_timing(
57 		const struct dc_crtc_timing *timing,
58 		const struct dpcd_caps *dpcd_caps)
59 {
60 	const struct dc_dongle_caps *dongle_caps = &dpcd_caps->dongle_caps;
61 
62 	switch (dpcd_caps->dongle_type) {
63 	case DISPLAY_DONGLE_DP_VGA_CONVERTER:
64 	case DISPLAY_DONGLE_DP_DVI_CONVERTER:
65 	case DISPLAY_DONGLE_DP_DVI_DONGLE:
66 		if (timing->pixel_encoding == PIXEL_ENCODING_RGB)
67 			return true;
68 		else
69 			return false;
70 	default:
71 		break;
72 	}
73 
74 	if (dpcd_caps->dongle_type == DISPLAY_DONGLE_DP_HDMI_CONVERTER &&
75 			dongle_caps->extendedCapValid == true) {
76 		/* Check Pixel Encoding */
77 		switch (timing->pixel_encoding) {
78 		case PIXEL_ENCODING_RGB:
79 		case PIXEL_ENCODING_YCBCR444:
80 			break;
81 		case PIXEL_ENCODING_YCBCR422:
82 			if (!dongle_caps->is_dp_hdmi_ycbcr422_pass_through)
83 				return false;
84 			break;
85 		case PIXEL_ENCODING_YCBCR420:
86 			if (!dongle_caps->is_dp_hdmi_ycbcr420_pass_through)
87 				return false;
88 			break;
89 		case PIXEL_ENCODING_UNDEFINED:
90 			/* These color depths are currently not supported */
91 			ASSERT(false);
92 			break;
93 		default:
94 			/* Invalid Pixel Encoding*/
95 			return false;
96 		}
97 
98 		switch (timing->display_color_depth) {
99 		case COLOR_DEPTH_666:
100 		case COLOR_DEPTH_888:
101 			/*888 and 666 should always be supported*/
102 			break;
103 		case COLOR_DEPTH_101010:
104 			if (dongle_caps->dp_hdmi_max_bpc < 10)
105 				return false;
106 			break;
107 		case COLOR_DEPTH_121212:
108 			if (dongle_caps->dp_hdmi_max_bpc < 12)
109 				return false;
110 			break;
111 		case COLOR_DEPTH_UNDEFINED:
112 			/* These color depths are currently not supported */
113 			ASSERT(false);
114 			break;
115 		case COLOR_DEPTH_141414:
116 		case COLOR_DEPTH_161616:
117 		default:
118 			/* These color depths are currently not supported */
119 			return false;
120 		}
121 
122 		/* Check 3D format */
123 		switch (timing->timing_3d_format) {
124 		case TIMING_3D_FORMAT_NONE:
125 		case TIMING_3D_FORMAT_FRAME_ALTERNATE:
126 			/*Only frame alternate 3D is supported on active dongle*/
127 			break;
128 		default:
129 			/*other 3D formats are not supported due to bad infoframe translation */
130 			return false;
131 		}
132 
133 		if (dongle_caps->dp_hdmi_frl_max_link_bw_in_kbps > 0) { // DP to HDMI FRL converter
134 			struct dc_crtc_timing outputTiming = *timing;
135 
136 			if (timing->flags.DSC && !timing->dsc_cfg.is_frl)
137 				/* DP input has DSC, HDMI FRL output doesn't have DSC, remove DSC from output timing */
138 				outputTiming.flags.DSC = 0;
139 			if (dc_bandwidth_in_kbps_from_timing(&outputTiming, DC_LINK_ENCODING_HDMI_FRL) >
140 					dongle_caps->dp_hdmi_frl_max_link_bw_in_kbps)
141 				return false;
142 		} else { // DP to HDMI TMDS converter
143 			if (get_tmds_output_pixel_clock_100hz(timing) > (dongle_caps->dp_hdmi_max_pixel_clk_in_khz * 10))
144 				return false;
145 		}
146 	}
147 
148 	if (dpcd_caps->channel_coding_cap.bits.DP_128b_132b_SUPPORTED == 0 &&
149 			dpcd_caps->dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_PASSTHROUGH_SUPPORT == 0 &&
150 			dongle_caps->dfp_cap_ext.supported) {
151 
152 		if (dongle_caps->dfp_cap_ext.max_pixel_rate_in_mps < (timing->pix_clk_100hz / 10000))
153 			return false;
154 
155 		if (dongle_caps->dfp_cap_ext.max_video_h_active_width < timing->h_addressable)
156 			return false;
157 
158 		if (dongle_caps->dfp_cap_ext.max_video_v_active_height < timing->v_addressable)
159 			return false;
160 
161 		if (timing->pixel_encoding == PIXEL_ENCODING_RGB) {
162 			if (!dongle_caps->dfp_cap_ext.encoding_format_caps.support_rgb)
163 				return false;
164 			if (timing->display_color_depth == COLOR_DEPTH_666 &&
165 					!dongle_caps->dfp_cap_ext.rgb_color_depth_caps.support_6bpc)
166 				return false;
167 			else if (timing->display_color_depth == COLOR_DEPTH_888 &&
168 					!dongle_caps->dfp_cap_ext.rgb_color_depth_caps.support_8bpc)
169 				return false;
170 			else if (timing->display_color_depth == COLOR_DEPTH_101010 &&
171 					!dongle_caps->dfp_cap_ext.rgb_color_depth_caps.support_10bpc)
172 				return false;
173 			else if (timing->display_color_depth == COLOR_DEPTH_121212 &&
174 					!dongle_caps->dfp_cap_ext.rgb_color_depth_caps.support_12bpc)
175 				return false;
176 			else if (timing->display_color_depth == COLOR_DEPTH_161616 &&
177 					!dongle_caps->dfp_cap_ext.rgb_color_depth_caps.support_16bpc)
178 				return false;
179 		} else if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR444) {
180 			if (!dongle_caps->dfp_cap_ext.encoding_format_caps.support_rgb)
181 				return false;
182 			if (timing->display_color_depth == COLOR_DEPTH_888 &&
183 					!dongle_caps->dfp_cap_ext.ycbcr444_color_depth_caps.support_8bpc)
184 				return false;
185 			else if (timing->display_color_depth == COLOR_DEPTH_101010 &&
186 					!dongle_caps->dfp_cap_ext.ycbcr444_color_depth_caps.support_10bpc)
187 				return false;
188 			else if (timing->display_color_depth == COLOR_DEPTH_121212 &&
189 					!dongle_caps->dfp_cap_ext.ycbcr444_color_depth_caps.support_12bpc)
190 				return false;
191 			else if (timing->display_color_depth == COLOR_DEPTH_161616 &&
192 					!dongle_caps->dfp_cap_ext.ycbcr444_color_depth_caps.support_16bpc)
193 				return false;
194 		} else if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR422) {
195 			if (!dongle_caps->dfp_cap_ext.encoding_format_caps.support_rgb)
196 				return false;
197 			if (timing->display_color_depth == COLOR_DEPTH_888 &&
198 					!dongle_caps->dfp_cap_ext.ycbcr422_color_depth_caps.support_8bpc)
199 				return false;
200 			else if (timing->display_color_depth == COLOR_DEPTH_101010 &&
201 					!dongle_caps->dfp_cap_ext.ycbcr422_color_depth_caps.support_10bpc)
202 				return false;
203 			else if (timing->display_color_depth == COLOR_DEPTH_121212 &&
204 					!dongle_caps->dfp_cap_ext.ycbcr422_color_depth_caps.support_12bpc)
205 				return false;
206 			else if (timing->display_color_depth == COLOR_DEPTH_161616 &&
207 					!dongle_caps->dfp_cap_ext.ycbcr422_color_depth_caps.support_16bpc)
208 				return false;
209 		} else if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR420) {
210 			if (!dongle_caps->dfp_cap_ext.encoding_format_caps.support_rgb)
211 				return false;
212 			if (timing->display_color_depth == COLOR_DEPTH_888 &&
213 					!dongle_caps->dfp_cap_ext.ycbcr420_color_depth_caps.support_8bpc)
214 				return false;
215 			else if (timing->display_color_depth == COLOR_DEPTH_101010 &&
216 					!dongle_caps->dfp_cap_ext.ycbcr420_color_depth_caps.support_10bpc)
217 				return false;
218 			else if (timing->display_color_depth == COLOR_DEPTH_121212 &&
219 					!dongle_caps->dfp_cap_ext.ycbcr420_color_depth_caps.support_12bpc)
220 				return false;
221 			else if (timing->display_color_depth == COLOR_DEPTH_161616 &&
222 					!dongle_caps->dfp_cap_ext.ycbcr420_color_depth_caps.support_16bpc)
223 				return false;
224 		}
225 	}
226 
227 	return true;
228 }
229 
230 uint32_t dp_link_bandwidth_kbps(
231 	const struct dc_link *link,
232 	const struct dc_link_settings *link_settings)
233 {
234 	uint32_t total_data_bw_efficiency_x10000 = 0;
235 	uint32_t link_rate_per_lane_kbps = 0;
236 
237 	switch (link_dp_get_encoding_format(link_settings)) {
238 	case DP_8b_10b_ENCODING:
239 		/* For 8b/10b encoding:
240 		 * link rate is defined in the unit of LINK_RATE_REF_FREQ_IN_KHZ per DP byte per lane.
241 		 * data bandwidth efficiency is 80% with additional 3% overhead if FEC is supported.
242 		 */
243 		link_rate_per_lane_kbps = link_settings->link_rate * LINK_RATE_REF_FREQ_IN_KHZ * BITS_PER_DP_BYTE;
244 		total_data_bw_efficiency_x10000 = DATA_EFFICIENCY_8b_10b_x10000;
245 		if (dp_should_enable_fec(link)) {
246 			total_data_bw_efficiency_x10000 /= 100;
247 			total_data_bw_efficiency_x10000 *= DATA_EFFICIENCY_8b_10b_FEC_EFFICIENCY_x100;
248 		}
249 		break;
250 	case DP_128b_132b_ENCODING:
251 		/* For 128b/132b encoding:
252 		 * link rate is defined in the unit of 10mbps per lane.
253 		 * total data bandwidth efficiency is always 96.71%.
254 		 */
255 		link_rate_per_lane_kbps = link_settings->link_rate * 10000;
256 		total_data_bw_efficiency_x10000 = DATA_EFFICIENCY_128b_132b_x10000;
257 		break;
258 	default:
259 		break;
260 	}
261 
262 	/* overall effective link bandwidth = link rate per lane * lane count * total data bandwidth efficiency */
263 	return link_rate_per_lane_kbps * link_settings->lane_count / 10000 * total_data_bw_efficiency_x10000;
264 }
265 
266 static bool dp_validate_mode_timing(
267 	struct dc_link *link,
268 	const struct dc_crtc_timing *timing)
269 {
270 	uint32_t req_bw;
271 	uint32_t max_bw;
272 
273 	const struct dc_link_settings *link_setting;
274 
275 	/* According to spec, VSC SDP should be used if pixel format is YCbCr420 */
276 	if (timing->pixel_encoding == PIXEL_ENCODING_YCBCR420 &&
277 			!link->dpcd_caps.dprx_feature.bits.VSC_SDP_COLORIMETRY_SUPPORTED &&
278 			dal_graphics_object_id_get_connector_id(link->link_id) != CONNECTOR_ID_VIRTUAL)
279 		return false;
280 
281 	/*always DP fail safe mode*/
282 	if ((timing->pix_clk_100hz / 10) == (uint32_t) 25175 &&
283 		timing->h_addressable == (uint32_t) 640 &&
284 		timing->v_addressable == (uint32_t) 480)
285 		return true;
286 
287 	link_setting = dp_get_verified_link_cap(link);
288 
289 	/* TODO: DYNAMIC_VALIDATION needs to be implemented */
290 	/*if (flags.DYNAMIC_VALIDATION == 1 &&
291 		link->verified_link_cap.lane_count != LANE_COUNT_UNKNOWN)
292 		link_setting = &link->verified_link_cap;
293 	*/
294 
295 	req_bw = dc_bandwidth_in_kbps_from_timing(timing, dc_link_get_highest_encoding_format(link));
296 	max_bw = dp_link_bandwidth_kbps(link, link_setting);
297 
298 	bool is_max_uncompressed_pixel_rate_exceeded = link->dpcd_caps.max_uncompressed_pixel_rate_cap.bits.valid &&
299 			timing->pix_clk_100hz > link->dpcd_caps.max_uncompressed_pixel_rate_cap.bits.max_uncompressed_pixel_rate_cap * 10000;
300 
301 	if (is_max_uncompressed_pixel_rate_exceeded && !timing->flags.DSC) {
302 		return false;
303 	}
304 
305 	if (req_bw <= max_bw) {
306 		/* remember the biggest mode here, during
307 		 * initial link training (to get
308 		 * verified_link_cap), LS sends event about
309 		 * cannot train at reported cap to upper
310 		 * layer and upper layer will re-enumerate modes.
311 		 * this is not necessary if the lower
312 		 * verified_link_cap is enough to drive
313 		 * all the modes */
314 
315 		/* TODO: DYNAMIC_VALIDATION needs to be implemented */
316 		/* if (flags.DYNAMIC_VALIDATION == 1)
317 			dpsst->max_req_bw_for_verified_linkcap = dal_max(
318 				dpsst->max_req_bw_for_verified_linkcap, req_bw); */
319 		return true;
320 	} else
321 		return false;
322 }
323 
324 enum dc_status link_validate_mode_timing(
325 		const struct dc_stream_state *stream,
326 		struct dc_link *link,
327 		const struct dc_crtc_timing *timing)
328 {
329 	uint32_t max_pix_clk = stream->link->dongle_max_pix_clk * 10;
330 	struct dpcd_caps *dpcd_caps = &link->dpcd_caps;
331 
332 	/* A hack to avoid failing any modes for EDID override feature on
333 	 * topology change such as lower quality cable for DP or different dongle
334 	 */
335 	if (link->remote_sinks[0] && link->remote_sinks[0]->sink_signal == SIGNAL_TYPE_VIRTUAL)
336 		return DC_OK;
337 
338 	/* Passive Dongle */
339 	if (max_pix_clk != 0 && get_tmds_output_pixel_clock_100hz(timing) > max_pix_clk)
340 		return DC_EXCEED_DONGLE_CAP;
341 
342 	/* Active Dongle*/
343 	if (!dp_active_dongle_validate_timing(timing, dpcd_caps))
344 		return DC_EXCEED_DONGLE_CAP;
345 
346 	switch (stream->signal) {
347 	case SIGNAL_TYPE_EDP:
348 	case SIGNAL_TYPE_DISPLAY_PORT:
349 		if (!dp_validate_mode_timing(
350 				link,
351 				timing))
352 			return DC_NO_DP_LINK_BANDWIDTH;
353 		break;
354 
355 	default:
356 		break;
357 	}
358 
359 	return DC_OK;
360 }
361 
362 /*
363  * This function calculates the bandwidth required for the stream timing
364  * and aggregates the stream bandwidth for the respective dpia link
365  *
366  * @stream: pointer to the dc_stream_state struct instance
367  * @num_streams: number of streams to be validated
368  *
369  * return: true if validation is succeeded
370  */
371 bool link_validate_dpia_bandwidth(const struct dc_stream_state *stream, const unsigned int num_streams)
372 {
373 	int bw_needed[MAX_DPIA_NUM] = {0};
374 	struct dc_link *dpia_link[MAX_DPIA_NUM] = {0};
375 	int num_dpias = 0;
376 
377 	for (unsigned int i = 0; i < num_streams; ++i) {
378 		if (stream[i].signal == SIGNAL_TYPE_DISPLAY_PORT) {
379 			/* new dpia sst stream, check whether it exceeds max dpia */
380 			if (num_dpias >= MAX_DPIA_NUM)
381 				return false;
382 
383 			dpia_link[num_dpias] = stream[i].link;
384 			bw_needed[num_dpias] = dc_bandwidth_in_kbps_from_timing(&stream[i].timing,
385 					dc_link_get_highest_encoding_format(dpia_link[num_dpias]));
386 			num_dpias++;
387 		} else if (stream[i].signal == SIGNAL_TYPE_DISPLAY_PORT_MST) {
388 			uint8_t j = 0;
389 			/* check whether its a known dpia link */
390 			for (; j < num_dpias; ++j) {
391 				if (dpia_link[j] == stream[i].link)
392 					break;
393 			}
394 
395 			if (j == num_dpias) {
396 				/* new dpia mst stream, check whether it exceeds max dpia */
397 				if (num_dpias >= MAX_DPIA_NUM)
398 					return false;
399 				else {
400 					dpia_link[j] = stream[i].link;
401 					num_dpias++;
402 				}
403 			}
404 
405 			bw_needed[j] += dc_bandwidth_in_kbps_from_timing(&stream[i].timing,
406 				dc_link_get_highest_encoding_format(dpia_link[j]));
407 		}
408 	}
409 
410 	/* Include dp overheads */
411 	for (uint8_t i = 0; i < num_dpias; ++i) {
412 		int dp_overhead = 0;
413 
414 		dp_overhead = link_dp_dpia_get_dp_overhead_in_dp_tunneling(dpia_link[i]);
415 		bw_needed[i] += dp_overhead;
416 	}
417 
418 	return dpia_validate_usb4_bw(dpia_link, bw_needed, num_dpias);
419 }
420 
421 struct dp_audio_layout_config {
422 	uint8_t layouts_per_sample_denom;
423 	uint8_t symbols_per_layout;
424 	uint8_t max_layouts_per_audio_sdp;
425 };
426 
427 static void get_audio_layout_config(
428 	uint32_t channel_count,
429 	enum dp_link_encoding encoding,
430 	struct dp_audio_layout_config *output)
431 {
432 	memset(output, 0, sizeof(struct dp_audio_layout_config));
433 
434 	/* Assuming L-PCM audio. Current implementation uses max 1 layout per SDP,
435 	 * with each layout being the same size (8ch layout).
436 	 */
437 	if (encoding == DP_8b_10b_ENCODING) {
438 		if (channel_count == 2) {
439 			output->layouts_per_sample_denom = 4;
440 			output->symbols_per_layout = 40;
441 			output->max_layouts_per_audio_sdp = 1;
442 		} else if (channel_count == 8 || channel_count == 6) {
443 			output->layouts_per_sample_denom = 1;
444 			output->symbols_per_layout = 40;
445 			output->max_layouts_per_audio_sdp = 1;
446 		}
447 	} else if (encoding == DP_128b_132b_ENCODING) {
448 		if (channel_count == 2) {
449 			output->layouts_per_sample_denom = 4;
450 			output->symbols_per_layout = 10;
451 			output->max_layouts_per_audio_sdp = 1;
452 		} else if (channel_count == 8 || channel_count == 6) {
453 			output->layouts_per_sample_denom = 1;
454 			output->symbols_per_layout = 10;
455 			output->max_layouts_per_audio_sdp = 1;
456 		}
457 	}
458 }
459 
460 static uint32_t get_av_stream_map_lane_count(
461 	enum dp_link_encoding encoding,
462 	enum dc_lane_count lane_count,
463 	bool is_mst)
464 {
465 	uint32_t av_stream_map_lane_count = 0;
466 
467 	if (encoding == DP_8b_10b_ENCODING) {
468 		if (!is_mst)
469 			av_stream_map_lane_count = lane_count;
470 		else
471 			av_stream_map_lane_count = 4;
472 	} else if (encoding == DP_128b_132b_ENCODING) {
473 		av_stream_map_lane_count = 4;
474 	}
475 
476 	ASSERT(av_stream_map_lane_count != 0);
477 
478 	return av_stream_map_lane_count;
479 }
480 
481 static uint32_t get_audio_sdp_overhead(
482 	enum dp_link_encoding encoding,
483 	enum dc_lane_count lane_count,
484 	bool is_mst)
485 {
486 	uint32_t audio_sdp_overhead = 0;
487 
488 	if (encoding == DP_8b_10b_ENCODING) {
489 		if (is_mst)
490 			audio_sdp_overhead = 16; /* 4 * 2 + 8 */
491 		else
492 			audio_sdp_overhead = lane_count * 2 + 8;
493 	} else if (encoding == DP_128b_132b_ENCODING) {
494 		audio_sdp_overhead = 10; /* 4 x 2.5 */
495 	}
496 
497 	ASSERT(audio_sdp_overhead != 0);
498 
499 	return audio_sdp_overhead;
500 }
501 
502 /* Current calculation only applicable for 8b/10b MST and 128b/132b SST/MST.
503  */
504 static uint32_t calculate_overhead_hblank_bw_in_symbols(
505 	uint32_t max_slice_h)
506 {
507 	uint32_t overhead_hblank_bw = 0; /* in stream symbols */
508 
509 	overhead_hblank_bw += max_slice_h * 4; /* EOC overhead */
510 	overhead_hblank_bw += 12; /* Main link overhead (VBID, BS/BE) */
511 
512 	return overhead_hblank_bw;
513 }
514 
515 uint32_t dp_required_hblank_size_bytes(
516 	const struct dc_link *link,
517 	struct dp_audio_bandwidth_params *audio_params)
518 {
519 	/* Main logic from dce_audio is duplicated here, with the main
520 	 * difference being:
521 	 * - Pre-determined lane count of 4
522 	 * - Assumed 16 dsc slices for worst case
523 	 * - Assumed SDP split disabled for worst case
524 	 * TODO: Unify logic from dce_audio to prevent duplicated logic.
525 	 */
526 
527 	const struct dc_crtc_timing *timing = audio_params->crtc_timing;
528 	const uint32_t channel_count = audio_params->channel_count;
529 	const uint32_t sample_rate_hz = audio_params->sample_rate_hz;
530 	const enum dp_link_encoding link_encoding = audio_params->link_encoding;
531 
532 	// 8b/10b MST and 128b/132b are always 4 logical lanes.
533 	const uint32_t lane_count = 4;
534 	const bool is_mst = (link->connector_signal == SIGNAL_TYPE_DISPLAY_PORT);
535 	// Maximum slice count is with ODM 4:1, 4 slices per DSC
536 	const uint32_t max_slices_h = 16;
537 
538 	const uint32_t av_stream_map_lane_count = get_av_stream_map_lane_count(
539 			link_encoding, lane_count, is_mst);
540 	const uint32_t audio_sdp_overhead = get_audio_sdp_overhead(
541 			link_encoding, lane_count, is_mst);
542 	struct dp_audio_layout_config layout_config;
543 
544 	if (link_encoding == DP_8b_10b_ENCODING && link->connector_signal == SIGNAL_TYPE_DISPLAY_PORT)
545 		return 0;
546 
547 	get_audio_layout_config(
548 			channel_count, link_encoding, &layout_config);
549 
550 	/* DP spec recommends between 1.05 to 1.1 safety margin to prevent sample under-run */
551 	struct fixed31_32 audio_sdp_margin = dc_fixpt_from_fraction(110, 100);
552 	struct fixed31_32 horizontal_line_freq_khz = dc_fixpt_from_fraction(
553 			timing->pix_clk_100hz, (long long)timing->h_total * 10);
554 	struct fixed31_32 samples_per_line;
555 	struct fixed31_32 layouts_per_line;
556 	struct fixed31_32 symbols_per_sdp_max_layout;
557 	struct fixed31_32 remainder;
558 	uint32_t num_sdp_with_max_layouts;
559 	uint32_t required_symbols_per_hblank;
560 	uint32_t required_bytes_per_hblank = 0;
561 
562 	samples_per_line = dc_fixpt_from_fraction(sample_rate_hz, 1000);
563 	samples_per_line = dc_fixpt_div(samples_per_line, horizontal_line_freq_khz);
564 	layouts_per_line = dc_fixpt_div_int(samples_per_line, layout_config.layouts_per_sample_denom);
565 	// HBlank expansion usage assumes SDP split disabled to allow for worst case.
566 	layouts_per_line = dc_fixpt_from_int(dc_fixpt_ceil(layouts_per_line));
567 
568 	num_sdp_with_max_layouts = dc_fixpt_floor(
569 			dc_fixpt_div_int(layouts_per_line, layout_config.max_layouts_per_audio_sdp));
570 	symbols_per_sdp_max_layout = dc_fixpt_from_int(
571 			layout_config.max_layouts_per_audio_sdp * layout_config.symbols_per_layout);
572 	symbols_per_sdp_max_layout = dc_fixpt_add_int(symbols_per_sdp_max_layout, audio_sdp_overhead);
573 	symbols_per_sdp_max_layout = dc_fixpt_mul(symbols_per_sdp_max_layout, audio_sdp_margin);
574 	required_symbols_per_hblank = num_sdp_with_max_layouts;
575 	required_symbols_per_hblank *= ((dc_fixpt_ceil(symbols_per_sdp_max_layout) + av_stream_map_lane_count) /
576 			av_stream_map_lane_count) *	av_stream_map_lane_count;
577 
578 	if (num_sdp_with_max_layouts !=	dc_fixpt_ceil(
579 			dc_fixpt_div_int(layouts_per_line, layout_config.max_layouts_per_audio_sdp))) {
580 		remainder = dc_fixpt_sub_int(layouts_per_line,
581 				num_sdp_with_max_layouts * layout_config.max_layouts_per_audio_sdp);
582 		remainder = dc_fixpt_mul_int(remainder, layout_config.symbols_per_layout);
583 		remainder = dc_fixpt_add_int(remainder, audio_sdp_overhead);
584 		remainder = dc_fixpt_mul(remainder, audio_sdp_margin);
585 		required_symbols_per_hblank += ((dc_fixpt_ceil(remainder) + av_stream_map_lane_count) /
586 				av_stream_map_lane_count) * av_stream_map_lane_count;
587 	}
588 
589 	required_symbols_per_hblank += calculate_overhead_hblank_bw_in_symbols(max_slices_h);
590 
591 	if (link_encoding == DP_8b_10b_ENCODING)
592 		required_bytes_per_hblank = required_symbols_per_hblank; // 8 bits per 8b/10b symbol
593 	else if (link_encoding == DP_128b_132b_ENCODING)
594 		required_bytes_per_hblank = required_symbols_per_hblank * 4; // 32 bits per 128b/132b symbol
595 
596 	return required_bytes_per_hblank;
597 }
598 
599