xref: /linux/drivers/gpu/drm/amd/display/dc/link/protocols/link_ddc.c (revision a1ff5a7d78a036d6c2178ee5acd6ba4946243800)
1 /*
2  * Copyright 2012-15 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  *
28  * This file implements generic display communication protocols such as i2c, aux
29  * and scdc. The file should not contain any specific applications of these
30  * protocols such as display capability query, detection, or handshaking such as
31  * link training.
32  */
33 #include "link_ddc.h"
34 #include "vector.h"
35 #include "dce/dce_aux.h"
36 #include "dal_asic_id.h"
37 #include "link_dpcd.h"
38 #include "dm_helpers.h"
39 #include "atomfirmware.h"
40 
41 #define DC_LOGGER \
42 	ddc_service->ctx->logger
43 #define DC_LOGGER_INIT(logger)
44 
45 static const uint8_t DP_VGA_DONGLE_BRANCH_DEV_NAME[] = "DpVga";
46 /* DP to Dual link DVI converter */
47 static const uint8_t DP_DVI_CONVERTER_ID_4[] = "m2DVIa";
48 static const uint8_t DP_DVI_CONVERTER_ID_5[] = "3393N2";
49 
50 struct i2c_payloads {
51 	struct vector payloads;
52 };
53 
i2c_payloads_create(struct dc_context * ctx,struct i2c_payloads * payloads,uint32_t count)54 static bool i2c_payloads_create(
55 		struct dc_context *ctx,
56 		struct i2c_payloads *payloads,
57 		uint32_t count)
58 {
59 	if (dal_vector_construct(
60 		&payloads->payloads, ctx, count, sizeof(struct i2c_payload)))
61 		return true;
62 
63 	return false;
64 }
65 
i2c_payloads_get(struct i2c_payloads * p)66 static struct i2c_payload *i2c_payloads_get(struct i2c_payloads *p)
67 {
68 	return (struct i2c_payload *)p->payloads.container;
69 }
70 
i2c_payloads_get_count(struct i2c_payloads * p)71 static uint32_t i2c_payloads_get_count(struct i2c_payloads *p)
72 {
73 	return p->payloads.count;
74 }
75 
i2c_payloads_destroy(struct i2c_payloads * p)76 static void i2c_payloads_destroy(struct i2c_payloads *p)
77 {
78 	if (!p)
79 		return;
80 
81 	dal_vector_destruct(&p->payloads);
82 }
83 
84 #define DDC_MIN(a, b) (((a) < (b)) ? (a) : (b))
85 
i2c_payloads_add(struct i2c_payloads * payloads,uint32_t address,uint32_t len,uint8_t * data,bool write)86 static void i2c_payloads_add(
87 	struct i2c_payloads *payloads,
88 	uint32_t address,
89 	uint32_t len,
90 	uint8_t *data,
91 	bool write)
92 {
93 	uint32_t payload_size = EDID_SEGMENT_SIZE;
94 	uint32_t pos;
95 
96 	for (pos = 0; pos < len; pos += payload_size) {
97 		struct i2c_payload payload = {
98 			.write = write,
99 			.address = address,
100 			.length = DDC_MIN(payload_size, len - pos),
101 			.data = data + pos };
102 		dal_vector_append(&payloads->payloads, &payload);
103 	}
104 
105 }
106 
ddc_service_construct(struct ddc_service * ddc_service,struct ddc_service_init_data * init_data)107 static void ddc_service_construct(
108 	struct ddc_service *ddc_service,
109 	struct ddc_service_init_data *init_data)
110 {
111 	enum connector_id connector_id =
112 		dal_graphics_object_id_get_connector_id(init_data->id);
113 
114 	struct gpio_service *gpio_service = init_data->ctx->gpio_service;
115 	struct graphics_object_i2c_info i2c_info;
116 	struct gpio_ddc_hw_info hw_info;
117 	struct dc_bios *dcb = init_data->ctx->dc_bios;
118 
119 	ddc_service->link = init_data->link;
120 	ddc_service->ctx = init_data->ctx;
121 
122 	if (init_data->is_dpia_link ||
123 	    dcb->funcs->get_i2c_info(dcb, init_data->id, &i2c_info) != BP_RESULT_OK) {
124 		ddc_service->ddc_pin = NULL;
125 	} else {
126 		DC_LOGGER_INIT(ddc_service->ctx->logger);
127 		DC_LOG_DC("BIOS object table - i2c_line: %d", i2c_info.i2c_line);
128 		DC_LOG_DC("BIOS object table - i2c_engine_id: %d", i2c_info.i2c_engine_id);
129 
130 		hw_info.ddc_channel = i2c_info.i2c_line;
131 		if (ddc_service->link != NULL)
132 			hw_info.hw_supported = i2c_info.i2c_hw_assist;
133 		else
134 			hw_info.hw_supported = false;
135 
136 		ddc_service->ddc_pin = dal_gpio_create_ddc(
137 			gpio_service,
138 			i2c_info.gpio_info.clk_a_register_index,
139 			1 << i2c_info.gpio_info.clk_a_shift,
140 			&hw_info);
141 	}
142 
143 	ddc_service->flags.EDID_QUERY_DONE_ONCE = false;
144 	ddc_service->flags.FORCE_READ_REPEATED_START = false;
145 	ddc_service->flags.EDID_STRESS_READ = false;
146 
147 	ddc_service->flags.IS_INTERNAL_DISPLAY =
148 		connector_id == CONNECTOR_ID_EDP ||
149 		connector_id == CONNECTOR_ID_LVDS;
150 
151 	ddc_service->wa.raw = 0;
152 }
153 
link_create_ddc_service(struct ddc_service_init_data * init_data)154 struct ddc_service *link_create_ddc_service(
155 	struct ddc_service_init_data *init_data)
156 {
157 	struct ddc_service *ddc_service;
158 
159 	ddc_service = kzalloc(sizeof(struct ddc_service), GFP_KERNEL);
160 
161 	if (!ddc_service)
162 		return NULL;
163 
164 	ddc_service_construct(ddc_service, init_data);
165 	return ddc_service;
166 }
167 
ddc_service_destruct(struct ddc_service * ddc)168 static void ddc_service_destruct(struct ddc_service *ddc)
169 {
170 	if (ddc->ddc_pin)
171 		dal_gpio_destroy_ddc(&ddc->ddc_pin);
172 }
173 
link_destroy_ddc_service(struct ddc_service ** ddc)174 void link_destroy_ddc_service(struct ddc_service **ddc)
175 {
176 	if (!ddc || !*ddc) {
177 		BREAK_TO_DEBUGGER();
178 		return;
179 	}
180 	ddc_service_destruct(*ddc);
181 	kfree(*ddc);
182 	*ddc = NULL;
183 }
184 
set_ddc_transaction_type(struct ddc_service * ddc,enum ddc_transaction_type type)185 void set_ddc_transaction_type(
186 	struct ddc_service *ddc,
187 	enum ddc_transaction_type type)
188 {
189 	ddc->transaction_type = type;
190 }
191 
link_is_in_aux_transaction_mode(struct ddc_service * ddc)192 bool link_is_in_aux_transaction_mode(struct ddc_service *ddc)
193 {
194 	switch (ddc->transaction_type) {
195 	case DDC_TRANSACTION_TYPE_I2C_OVER_AUX:
196 	case DDC_TRANSACTION_TYPE_I2C_OVER_AUX_WITH_DEFER:
197 	case DDC_TRANSACTION_TYPE_I2C_OVER_AUX_RETRY_DEFER:
198 		return true;
199 	default:
200 		break;
201 	}
202 	return false;
203 }
204 
set_dongle_type(struct ddc_service * ddc,enum display_dongle_type dongle_type)205 void set_dongle_type(struct ddc_service *ddc,
206 		enum display_dongle_type dongle_type)
207 {
208 	ddc->dongle_type = dongle_type;
209 }
210 
defer_delay_converter_wa(struct ddc_service * ddc,uint32_t defer_delay)211 static uint32_t defer_delay_converter_wa(
212 	struct ddc_service *ddc,
213 	uint32_t defer_delay)
214 {
215 	struct dc_link *link = ddc->link;
216 
217 	if (link->dpcd_caps.dongle_type == DISPLAY_DONGLE_DP_VGA_CONVERTER &&
218 		link->dpcd_caps.branch_dev_id == DP_BRANCH_DEVICE_ID_0080E1 &&
219 		(link->dpcd_caps.branch_fw_revision[0] < 0x01 ||
220 				(link->dpcd_caps.branch_fw_revision[0] == 0x01 &&
221 				link->dpcd_caps.branch_fw_revision[1] < 0x40)) &&
222 		!memcmp(link->dpcd_caps.branch_dev_name,
223 		    DP_VGA_DONGLE_BRANCH_DEV_NAME,
224 			sizeof(link->dpcd_caps.branch_dev_name)))
225 
226 		return defer_delay > DPVGA_DONGLE_AUX_DEFER_WA_DELAY ?
227 			defer_delay : DPVGA_DONGLE_AUX_DEFER_WA_DELAY;
228 
229 	if (link->dpcd_caps.branch_dev_id == DP_BRANCH_DEVICE_ID_0080E1 &&
230 	    !memcmp(link->dpcd_caps.branch_dev_name,
231 		    DP_DVI_CONVERTER_ID_4,
232 		    sizeof(link->dpcd_caps.branch_dev_name)))
233 		return defer_delay > I2C_OVER_AUX_DEFER_WA_DELAY ?
234 			defer_delay : I2C_OVER_AUX_DEFER_WA_DELAY;
235 	if (link->dpcd_caps.branch_dev_id == DP_BRANCH_DEVICE_ID_006037 &&
236 	    !memcmp(link->dpcd_caps.branch_dev_name,
237 		    DP_DVI_CONVERTER_ID_5,
238 		    sizeof(link->dpcd_caps.branch_dev_name)))
239 		return defer_delay > I2C_OVER_AUX_DEFER_WA_DELAY_1MS ?
240 			I2C_OVER_AUX_DEFER_WA_DELAY_1MS : defer_delay;
241 
242 	return defer_delay;
243 }
244 
245 #define DP_TRANSLATOR_DELAY 5
246 
link_get_aux_defer_delay(struct ddc_service * ddc)247 uint32_t link_get_aux_defer_delay(struct ddc_service *ddc)
248 {
249 	uint32_t defer_delay = 0;
250 
251 	switch (ddc->transaction_type) {
252 	case DDC_TRANSACTION_TYPE_I2C_OVER_AUX:
253 		if ((DISPLAY_DONGLE_DP_VGA_CONVERTER == ddc->dongle_type) ||
254 			(DISPLAY_DONGLE_DP_DVI_CONVERTER == ddc->dongle_type) ||
255 			(DISPLAY_DONGLE_DP_HDMI_CONVERTER ==
256 				ddc->dongle_type)) {
257 
258 			defer_delay = DP_TRANSLATOR_DELAY;
259 
260 			defer_delay =
261 				defer_delay_converter_wa(ddc, defer_delay);
262 
263 		} else /*sink has a delay different from an Active Converter*/
264 			defer_delay = 0;
265 		break;
266 	case DDC_TRANSACTION_TYPE_I2C_OVER_AUX_WITH_DEFER:
267 		defer_delay = DP_TRANSLATOR_DELAY;
268 		break;
269 	default:
270 		break;
271 	}
272 	return defer_delay;
273 }
274 
submit_aux_command(struct ddc_service * ddc,struct aux_payload * payload)275 static bool submit_aux_command(struct ddc_service *ddc,
276 		struct aux_payload *payload)
277 {
278 	uint32_t retrieved = 0;
279 	bool ret = false;
280 
281 	if (!ddc)
282 		return false;
283 
284 	if (!payload)
285 		return false;
286 
287 	do {
288 		struct aux_payload current_payload;
289 		bool is_end_of_payload = (retrieved + DEFAULT_AUX_MAX_DATA_SIZE) >=
290 				payload->length;
291 		uint32_t payload_length = is_end_of_payload ?
292 				payload->length - retrieved : DEFAULT_AUX_MAX_DATA_SIZE;
293 
294 		current_payload.address = payload->address;
295 		current_payload.data = &payload->data[retrieved];
296 		current_payload.defer_delay = payload->defer_delay;
297 		current_payload.i2c_over_aux = payload->i2c_over_aux;
298 		current_payload.length = payload_length;
299 		/* set mot (middle of transaction) to false if it is the last payload */
300 		current_payload.mot = is_end_of_payload ? payload->mot:true;
301 		current_payload.write_status_update = false;
302 		current_payload.reply = payload->reply;
303 		current_payload.write = payload->write;
304 
305 		ret = link_aux_transfer_with_retries_no_mutex(ddc, &current_payload);
306 
307 		retrieved += payload_length;
308 	} while (retrieved < payload->length && ret == true);
309 
310 	return ret;
311 }
312 
link_query_ddc_data(struct ddc_service * ddc,uint32_t address,uint8_t * write_buf,uint32_t write_size,uint8_t * read_buf,uint32_t read_size)313 bool link_query_ddc_data(
314 	struct ddc_service *ddc,
315 	uint32_t address,
316 	uint8_t *write_buf,
317 	uint32_t write_size,
318 	uint8_t *read_buf,
319 	uint32_t read_size)
320 {
321 	bool success = true;
322 	uint32_t payload_size =
323 		link_is_in_aux_transaction_mode(ddc) ?
324 			DEFAULT_AUX_MAX_DATA_SIZE : EDID_SEGMENT_SIZE;
325 
326 	uint32_t write_payloads =
327 		(write_size + payload_size - 1) / payload_size;
328 
329 	uint32_t read_payloads =
330 		(read_size + payload_size - 1) / payload_size;
331 
332 	uint32_t payloads_num = write_payloads + read_payloads;
333 
334 	if (!payloads_num)
335 		return false;
336 
337 	if (link_is_in_aux_transaction_mode(ddc)) {
338 		struct aux_payload payload;
339 
340 		payload.i2c_over_aux = true;
341 		payload.address = address;
342 		payload.reply = NULL;
343 		payload.defer_delay = link_get_aux_defer_delay(ddc);
344 		payload.write_status_update = false;
345 
346 		if (write_size != 0) {
347 			payload.write = true;
348 			/* should not set mot (middle of transaction) to 0
349 			 * if there are pending read payloads
350 			 */
351 			payload.mot = !(read_size == 0);
352 			payload.length = write_size;
353 			payload.data = write_buf;
354 
355 			success = submit_aux_command(ddc, &payload);
356 		}
357 
358 		if (read_size != 0 && success) {
359 			payload.write = false;
360 			/* should set mot (middle of transaction) to 0
361 			 * since it is the last payload to send
362 			 */
363 			payload.mot = false;
364 			payload.length = read_size;
365 			payload.data = read_buf;
366 
367 			success = submit_aux_command(ddc, &payload);
368 		}
369 	} else {
370 		struct i2c_command command = {0};
371 		struct i2c_payloads payloads;
372 
373 		if (!i2c_payloads_create(ddc->ctx, &payloads, payloads_num))
374 			return false;
375 
376 		command.payloads = i2c_payloads_get(&payloads);
377 		command.number_of_payloads = 0;
378 		command.engine = DDC_I2C_COMMAND_ENGINE;
379 		command.speed = ddc->ctx->dc->caps.i2c_speed_in_khz;
380 
381 		i2c_payloads_add(
382 			&payloads, address, write_size, write_buf, true);
383 
384 		i2c_payloads_add(
385 			&payloads, address, read_size, read_buf, false);
386 
387 		command.number_of_payloads =
388 			i2c_payloads_get_count(&payloads);
389 
390 		success = dm_helpers_submit_i2c(
391 				ddc->ctx,
392 				ddc->link,
393 				&command);
394 
395 		i2c_payloads_destroy(&payloads);
396 	}
397 
398 	return success;
399 }
400 
link_aux_transfer_raw(struct ddc_service * ddc,struct aux_payload * payload,enum aux_return_code_type * operation_result)401 int link_aux_transfer_raw(struct ddc_service *ddc,
402 		struct aux_payload *payload,
403 		enum aux_return_code_type *operation_result)
404 {
405 	if (ddc->ctx->dc->debug.enable_dmub_aux_for_legacy_ddc ||
406 	    !ddc->ddc_pin) {
407 		return dce_aux_transfer_dmub_raw(ddc, payload, operation_result);
408 	} else {
409 		return dce_aux_transfer_raw(ddc, payload, operation_result);
410 	}
411 }
412 
link_get_fixed_vs_pe_retimer_write_address(struct dc_link * link)413 uint32_t link_get_fixed_vs_pe_retimer_write_address(struct dc_link *link)
414 {
415 	uint32_t vendor_lttpr_write_address = 0xF004F;
416 	uint8_t offset;
417 
418 	switch (link->dpcd_caps.lttpr_caps.phy_repeater_cnt) {
419 	case 0x80: // 1 lttpr repeater
420 		offset =  1;
421 		break;
422 	case 0x40: // 2 lttpr repeaters
423 		offset = 2;
424 		break;
425 	case 0x20: // 3 lttpr repeaters
426 		offset = 3;
427 		break;
428 	case 0x10: // 4 lttpr repeaters
429 		offset = 4;
430 		break;
431 	case 0x08: // 5 lttpr repeaters
432 		offset = 5;
433 		break;
434 	case 0x04: // 6 lttpr repeaters
435 		offset = 6;
436 		break;
437 	case 0x02: // 7 lttpr repeaters
438 		offset = 7;
439 		break;
440 	case 0x01: // 8 lttpr repeaters
441 		offset = 8;
442 		break;
443 	default:
444 		offset = 0xFF;
445 	}
446 
447 	if (offset != 0xFF) {
448 		vendor_lttpr_write_address +=
449 				((DP_REPEATER_CONFIGURATION_AND_STATUS_SIZE) * (offset - 1));
450 	}
451 	return vendor_lttpr_write_address;
452 }
453 
link_get_fixed_vs_pe_retimer_read_address(struct dc_link * link)454 uint32_t link_get_fixed_vs_pe_retimer_read_address(struct dc_link *link)
455 {
456 	return link_get_fixed_vs_pe_retimer_write_address(link) + 4;
457 }
458 
link_configure_fixed_vs_pe_retimer(struct ddc_service * ddc,const uint8_t * data,uint32_t length)459 bool link_configure_fixed_vs_pe_retimer(struct ddc_service *ddc, const uint8_t *data, uint32_t length)
460 {
461 	struct aux_payload write_payload = {
462 		.i2c_over_aux = false,
463 		.write = true,
464 		.address = link_get_fixed_vs_pe_retimer_write_address(ddc->link),
465 		.length = length,
466 		.data = (uint8_t *) data,
467 		.reply = NULL,
468 		.mot = I2C_MOT_UNDEF,
469 		.write_status_update = false,
470 		.defer_delay = 0,
471 	};
472 
473 	return link_aux_transfer_with_retries_no_mutex(ddc,
474 			&write_payload);
475 }
476 
link_query_fixed_vs_pe_retimer(struct ddc_service * ddc,uint8_t * data,uint32_t length)477 bool link_query_fixed_vs_pe_retimer(struct ddc_service *ddc, uint8_t *data, uint32_t length)
478 {
479 	struct aux_payload read_payload = {
480 		.i2c_over_aux = false,
481 		.write = false,
482 		.address = link_get_fixed_vs_pe_retimer_read_address(ddc->link),
483 		.length = length,
484 		.data = data,
485 		.reply = NULL,
486 		.mot = I2C_MOT_UNDEF,
487 		.write_status_update = false,
488 		.defer_delay = 0,
489 	};
490 
491 	return link_aux_transfer_with_retries_no_mutex(ddc,
492 			&read_payload);
493 }
494 
link_aux_transfer_with_retries_no_mutex(struct ddc_service * ddc,struct aux_payload * payload)495 bool link_aux_transfer_with_retries_no_mutex(struct ddc_service *ddc,
496 		struct aux_payload *payload)
497 {
498 	return dce_aux_transfer_with_retries(ddc, payload);
499 }
500 
501 
try_to_configure_aux_timeout(struct ddc_service * ddc,uint32_t timeout)502 bool try_to_configure_aux_timeout(struct ddc_service *ddc,
503 		uint32_t timeout)
504 {
505 	bool result = false;
506 	struct ddc *ddc_pin = ddc->ddc_pin;
507 
508 	if ((ddc->link->chip_caps & EXT_DISPLAY_PATH_CAPS__DP_FIXED_VS_EN) &&
509 			!ddc->link->dc->debug.disable_fixed_vs_aux_timeout_wa &&
510 			ddc->ctx->dce_version == DCN_VERSION_3_1) {
511 		/* Fixed VS workaround for AUX timeout */
512 		const uint32_t fixed_vs_address = 0xF004F;
513 		const uint8_t fixed_vs_data[4] = {0x1, 0x22, 0x63, 0xc};
514 
515 		core_link_write_dpcd(ddc->link,
516 				fixed_vs_address,
517 				fixed_vs_data,
518 				sizeof(fixed_vs_data));
519 
520 		timeout = 3072;
521 	}
522 
523 	/* Do not try to access nonexistent DDC pin. */
524 	if (ddc->link->ep_type != DISPLAY_ENDPOINT_PHY)
525 		return true;
526 
527 	if (ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en]->funcs->configure_timeout) {
528 		ddc->ctx->dc->res_pool->engines[ddc_pin->pin_data->en]->funcs->configure_timeout(ddc, timeout);
529 		result = true;
530 	}
531 
532 	return result;
533 }
534 
get_ddc_pin(struct ddc_service * ddc_service)535 struct ddc *get_ddc_pin(struct ddc_service *ddc_service)
536 {
537 	return ddc_service->ddc_pin;
538 }
539 
write_scdc_data(struct ddc_service * ddc_service,uint32_t pix_clk,bool lte_340_scramble)540 void write_scdc_data(struct ddc_service *ddc_service,
541 		uint32_t pix_clk,
542 		bool lte_340_scramble)
543 {
544 	bool over_340_mhz = pix_clk > 340000 ? 1 : 0;
545 	uint8_t slave_address = HDMI_SCDC_ADDRESS;
546 	uint8_t offset = HDMI_SCDC_SINK_VERSION;
547 	uint8_t sink_version = 0;
548 	uint8_t write_buffer[2] = {0};
549 	/*Lower than 340 Scramble bit from SCDC caps*/
550 
551 	if (ddc_service->link->local_sink &&
552 		ddc_service->link->local_sink->edid_caps.panel_patch.skip_scdc_overwrite)
553 		return;
554 
555 	link_query_ddc_data(ddc_service, slave_address, &offset,
556 			sizeof(offset), &sink_version, sizeof(sink_version));
557 	if (sink_version == 1) {
558 		/*Source Version = 1*/
559 		write_buffer[0] = HDMI_SCDC_SOURCE_VERSION;
560 		write_buffer[1] = 1;
561 		link_query_ddc_data(ddc_service, slave_address,
562 				write_buffer, sizeof(write_buffer), NULL, 0);
563 		/*Read Request from SCDC caps*/
564 	}
565 	write_buffer[0] = HDMI_SCDC_TMDS_CONFIG;
566 
567 	if (over_340_mhz) {
568 		write_buffer[1] = 3;
569 	} else if (lte_340_scramble) {
570 		write_buffer[1] = 1;
571 	} else {
572 		write_buffer[1] = 0;
573 	}
574 	link_query_ddc_data(ddc_service, slave_address, write_buffer,
575 			sizeof(write_buffer), NULL, 0);
576 }
577 
read_scdc_data(struct ddc_service * ddc_service)578 void read_scdc_data(struct ddc_service *ddc_service)
579 {
580 	uint8_t slave_address = HDMI_SCDC_ADDRESS;
581 	uint8_t offset = HDMI_SCDC_TMDS_CONFIG;
582 	uint8_t tmds_config = 0;
583 
584 	if (ddc_service->link->local_sink &&
585 		ddc_service->link->local_sink->edid_caps.panel_patch.skip_scdc_overwrite)
586 		return;
587 
588 	link_query_ddc_data(ddc_service, slave_address, &offset,
589 			sizeof(offset), &tmds_config, sizeof(tmds_config));
590 	if (tmds_config & 0x1) {
591 		union hdmi_scdc_status_flags_data status_data = {0};
592 		uint8_t scramble_status = 0;
593 
594 		offset = HDMI_SCDC_SCRAMBLER_STATUS;
595 		link_query_ddc_data(ddc_service, slave_address,
596 				&offset, sizeof(offset), &scramble_status,
597 				sizeof(scramble_status));
598 		offset = HDMI_SCDC_STATUS_FLAGS;
599 		link_query_ddc_data(ddc_service, slave_address,
600 				&offset, sizeof(offset), &status_data.byte,
601 				sizeof(status_data.byte));
602 	}
603 }
604