xref: /linux/drivers/gpu/drm/nouveau/nouveau_dp.c (revision f2ee442115c9b6219083c019939a9cc0c9abb2f8)
1 /*
2  * Copyright 2009 Red Hat 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: Ben Skeggs
23  */
24 
25 #include "drmP.h"
26 
27 #include "nouveau_drv.h"
28 #include "nouveau_i2c.h"
29 #include "nouveau_connector.h"
30 #include "nouveau_encoder.h"
31 #include "nouveau_crtc.h"
32 
33 /******************************************************************************
34  * aux channel util functions
35  *****************************************************************************/
36 #define AUX_DBG(fmt, args...) do {                                             \
37 	if (nouveau_reg_debug & NOUVEAU_REG_DEBUG_AUXCH) {                     \
38 		NV_PRINTK(KERN_DEBUG, dev, "AUXCH(%d): " fmt, ch, ##args);     \
39 	}                                                                      \
40 } while (0)
41 #define AUX_ERR(fmt, args...) NV_ERROR(dev, "AUXCH(%d): " fmt, ch, ##args)
42 
43 static void
44 auxch_fini(struct drm_device *dev, int ch)
45 {
46 	nv_mask(dev, 0x00e4e4 + (ch * 0x50), 0x00310000, 0x00000000);
47 }
48 
49 static int
50 auxch_init(struct drm_device *dev, int ch)
51 {
52 	const u32 unksel = 1; /* nfi which to use, or if it matters.. */
53 	const u32 ureq = unksel ? 0x00100000 : 0x00200000;
54 	const u32 urep = unksel ? 0x01000000 : 0x02000000;
55 	u32 ctrl, timeout;
56 
57 	/* wait up to 1ms for any previous transaction to be done... */
58 	timeout = 1000;
59 	do {
60 		ctrl = nv_rd32(dev, 0x00e4e4 + (ch * 0x50));
61 		udelay(1);
62 		if (!timeout--) {
63 			AUX_ERR("begin idle timeout 0x%08x", ctrl);
64 			return -EBUSY;
65 		}
66 	} while (ctrl & 0x03010000);
67 
68 	/* set some magic, and wait up to 1ms for it to appear */
69 	nv_mask(dev, 0x00e4e4 + (ch * 0x50), 0x00300000, ureq);
70 	timeout = 1000;
71 	do {
72 		ctrl = nv_rd32(dev, 0x00e4e4 + (ch * 0x50));
73 		udelay(1);
74 		if (!timeout--) {
75 			AUX_ERR("magic wait 0x%08x\n", ctrl);
76 			auxch_fini(dev, ch);
77 			return -EBUSY;
78 		}
79 	} while ((ctrl & 0x03000000) != urep);
80 
81 	return 0;
82 }
83 
84 static int
85 auxch_tx(struct drm_device *dev, int ch, u8 type, u32 addr, u8 *data, u8 size)
86 {
87 	u32 ctrl, stat, timeout, retries;
88 	u32 xbuf[4] = {};
89 	int ret, i;
90 
91 	AUX_DBG("%d: 0x%08x %d\n", type, addr, size);
92 
93 	ret = auxch_init(dev, ch);
94 	if (ret)
95 		goto out;
96 
97 	stat = nv_rd32(dev, 0x00e4e8 + (ch * 0x50));
98 	if (!(stat & 0x10000000)) {
99 		AUX_DBG("sink not detected\n");
100 		ret = -ENXIO;
101 		goto out;
102 	}
103 
104 	if (!(type & 1)) {
105 		memcpy(xbuf, data, size);
106 		for (i = 0; i < 16; i += 4) {
107 			AUX_DBG("wr 0x%08x\n", xbuf[i / 4]);
108 			nv_wr32(dev, 0x00e4c0 + (ch * 0x50) + i, xbuf[i / 4]);
109 		}
110 	}
111 
112 	ctrl  = nv_rd32(dev, 0x00e4e4 + (ch * 0x50));
113 	ctrl &= ~0x0001f0ff;
114 	ctrl |= type << 12;
115 	ctrl |= size - 1;
116 	nv_wr32(dev, 0x00e4e0 + (ch * 0x50), addr);
117 
118 	/* retry transaction a number of times on failure... */
119 	ret = -EREMOTEIO;
120 	for (retries = 0; retries < 32; retries++) {
121 		/* reset, and delay a while if this is a retry */
122 		nv_wr32(dev, 0x00e4e4 + (ch * 0x50), 0x80000000 | ctrl);
123 		nv_wr32(dev, 0x00e4e4 + (ch * 0x50), 0x00000000 | ctrl);
124 		if (retries)
125 			udelay(400);
126 
127 		/* transaction request, wait up to 1ms for it to complete */
128 		nv_wr32(dev, 0x00e4e4 + (ch * 0x50), 0x00010000 | ctrl);
129 
130 		timeout = 1000;
131 		do {
132 			ctrl = nv_rd32(dev, 0x00e4e4 + (ch * 0x50));
133 			udelay(1);
134 			if (!timeout--) {
135 				AUX_ERR("tx req timeout 0x%08x\n", ctrl);
136 				goto out;
137 			}
138 		} while (ctrl & 0x00010000);
139 
140 		/* read status, and check if transaction completed ok */
141 		stat = nv_mask(dev, 0x00e4e8 + (ch * 0x50), 0, 0);
142 		if (!(stat & 0x000f0f00)) {
143 			ret = 0;
144 			break;
145 		}
146 
147 		AUX_DBG("%02d 0x%08x 0x%08x\n", retries, ctrl, stat);
148 	}
149 
150 	if (type & 1) {
151 		for (i = 0; i < 16; i += 4) {
152 			xbuf[i / 4] = nv_rd32(dev, 0x00e4d0 + (ch * 0x50) + i);
153 			AUX_DBG("rd 0x%08x\n", xbuf[i / 4]);
154 		}
155 		memcpy(data, xbuf, size);
156 	}
157 
158 out:
159 	auxch_fini(dev, ch);
160 	return ret;
161 }
162 
163 static u32
164 dp_link_bw_get(struct drm_device *dev, int or, int link)
165 {
166 	u32 ctrl = nv_rd32(dev, 0x614300 + (or * 0x800));
167 	if (!(ctrl & 0x000c0000))
168 		return 162000;
169 	return 270000;
170 }
171 
172 static int
173 dp_lane_count_get(struct drm_device *dev, int or, int link)
174 {
175 	u32 ctrl = nv_rd32(dev, NV50_SOR_DP_CTRL(or, link));
176 	switch (ctrl & 0x000f0000) {
177 	case 0x00010000: return 1;
178 	case 0x00030000: return 2;
179 	default:
180 		return 4;
181 	}
182 }
183 
184 void
185 nouveau_dp_tu_update(struct drm_device *dev, int or, int link, u32 clk, u32 bpp)
186 {
187 	const u32 symbol = 100000;
188 	int bestTU = 0, bestVTUi = 0, bestVTUf = 0, bestVTUa = 0;
189 	int TU, VTUi, VTUf, VTUa;
190 	u64 link_data_rate, link_ratio, unk;
191 	u32 best_diff = 64 * symbol;
192 	u32 link_nr, link_bw, r;
193 
194 	/* calculate packed data rate for each lane */
195 	link_nr = dp_lane_count_get(dev, or, link);
196 	link_data_rate = (clk * bpp / 8) / link_nr;
197 
198 	/* calculate ratio of packed data rate to link symbol rate */
199 	link_bw = dp_link_bw_get(dev, or, link);
200 	link_ratio = link_data_rate * symbol;
201 	r = do_div(link_ratio, link_bw);
202 
203 	for (TU = 64; TU >= 32; TU--) {
204 		/* calculate average number of valid symbols in each TU */
205 		u32 tu_valid = link_ratio * TU;
206 		u32 calc, diff;
207 
208 		/* find a hw representation for the fraction.. */
209 		VTUi = tu_valid / symbol;
210 		calc = VTUi * symbol;
211 		diff = tu_valid - calc;
212 		if (diff) {
213 			if (diff >= (symbol / 2)) {
214 				VTUf = symbol / (symbol - diff);
215 				if (symbol - (VTUf * diff))
216 					VTUf++;
217 
218 				if (VTUf <= 15) {
219 					VTUa  = 1;
220 					calc += symbol - (symbol / VTUf);
221 				} else {
222 					VTUa  = 0;
223 					VTUf  = 1;
224 					calc += symbol;
225 				}
226 			} else {
227 				VTUa  = 0;
228 				VTUf  = min((int)(symbol / diff), 15);
229 				calc += symbol / VTUf;
230 			}
231 
232 			diff = calc - tu_valid;
233 		} else {
234 			/* no remainder, but the hw doesn't like the fractional
235 			 * part to be zero.  decrement the integer part and
236 			 * have the fraction add a whole symbol back
237 			 */
238 			VTUa = 0;
239 			VTUf = 1;
240 			VTUi--;
241 		}
242 
243 		if (diff < best_diff) {
244 			best_diff = diff;
245 			bestTU = TU;
246 			bestVTUa = VTUa;
247 			bestVTUf = VTUf;
248 			bestVTUi = VTUi;
249 			if (diff == 0)
250 				break;
251 		}
252 	}
253 
254 	if (!bestTU) {
255 		NV_ERROR(dev, "DP: unable to find suitable config\n");
256 		return;
257 	}
258 
259 	/* XXX close to vbios numbers, but not right */
260 	unk  = (symbol - link_ratio) * bestTU;
261 	unk *= link_ratio;
262 	r = do_div(unk, symbol);
263 	r = do_div(unk, symbol);
264 	unk += 6;
265 
266 	nv_mask(dev, NV50_SOR_DP_CTRL(or, link), 0x000001fc, bestTU << 2);
267 	nv_mask(dev, NV50_SOR_DP_SCFG(or, link), 0x010f7f3f, bestVTUa << 24 |
268 							     bestVTUf << 16 |
269 							     bestVTUi << 8 |
270 							     unk);
271 }
272 
273 u8 *
274 nouveau_dp_bios_data(struct drm_device *dev, struct dcb_entry *dcb, u8 **entry)
275 {
276 	struct drm_nouveau_private *dev_priv = dev->dev_private;
277 	struct nvbios *bios = &dev_priv->vbios;
278 	struct bit_entry d;
279 	u8 *table;
280 	int i;
281 
282 	if (bit_table(dev, 'd', &d)) {
283 		NV_ERROR(dev, "BIT 'd' table not found\n");
284 		return NULL;
285 	}
286 
287 	if (d.version != 1) {
288 		NV_ERROR(dev, "BIT 'd' table version %d unknown\n", d.version);
289 		return NULL;
290 	}
291 
292 	table = ROMPTR(bios, d.data[0]);
293 	if (!table) {
294 		NV_ERROR(dev, "displayport table pointer invalid\n");
295 		return NULL;
296 	}
297 
298 	switch (table[0]) {
299 	case 0x20:
300 	case 0x21:
301 	case 0x30:
302 		break;
303 	default:
304 		NV_ERROR(dev, "displayport table 0x%02x unknown\n", table[0]);
305 		return NULL;
306 	}
307 
308 	for (i = 0; i < table[3]; i++) {
309 		*entry = ROMPTR(bios, table[table[1] + (i * table[2])]);
310 		if (*entry && bios_encoder_match(dcb, ROM32((*entry)[0])))
311 			return table;
312 	}
313 
314 	NV_ERROR(dev, "displayport encoder table not found\n");
315 	return NULL;
316 }
317 
318 /******************************************************************************
319  * link training
320  *****************************************************************************/
321 struct dp_state {
322 	struct dcb_entry *dcb;
323 	u8 *table;
324 	u8 *entry;
325 	int auxch;
326 	int crtc;
327 	int or;
328 	int link;
329 	u8 *dpcd;
330 	int link_nr;
331 	u32 link_bw;
332 	u8  stat[6];
333 	u8  conf[4];
334 };
335 
336 static void
337 dp_set_link_config(struct drm_device *dev, struct dp_state *dp)
338 {
339 	struct drm_nouveau_private *dev_priv = dev->dev_private;
340 	int or = dp->or, link = dp->link;
341 	u8 *entry, sink[2];
342 	u32 dp_ctrl;
343 	u16 script;
344 
345 	NV_DEBUG_KMS(dev, "%d lanes at %d KB/s\n", dp->link_nr, dp->link_bw);
346 
347 	/* set selected link rate on source */
348 	switch (dp->link_bw) {
349 	case 270000:
350 		nv_mask(dev, 0x614300 + (or * 0x800), 0x000c0000, 0x00040000);
351 		sink[0] = DP_LINK_BW_2_7;
352 		break;
353 	default:
354 		nv_mask(dev, 0x614300 + (or * 0x800), 0x000c0000, 0x00000000);
355 		sink[0] = DP_LINK_BW_1_62;
356 		break;
357 	}
358 
359 	/* offset +0x0a of each dp encoder table entry is a pointer to another
360 	 * table, that has (among other things) pointers to more scripts that
361 	 * need to be executed, this time depending on link speed.
362 	 */
363 	entry = ROMPTR(&dev_priv->vbios, dp->entry[10]);
364 	if (entry) {
365 		if (dp->table[0] < 0x30) {
366 			while (dp->link_bw < (ROM16(entry[0]) * 10))
367 				entry += 4;
368 			script = ROM16(entry[2]);
369 		} else {
370 			while (dp->link_bw < (entry[0] * 27000))
371 				entry += 3;
372 			script = ROM16(entry[1]);
373 		}
374 
375 		nouveau_bios_run_init_table(dev, script, dp->dcb, dp->crtc);
376 	}
377 
378 	/* configure lane count on the source */
379 	dp_ctrl = ((1 << dp->link_nr) - 1) << 16;
380 	sink[1] = dp->link_nr;
381 	if (dp->dpcd[2] & DP_ENHANCED_FRAME_CAP) {
382 		dp_ctrl |= 0x00004000;
383 		sink[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
384 	}
385 
386 	nv_mask(dev, NV50_SOR_DP_CTRL(or, link), 0x001f4000, dp_ctrl);
387 
388 	/* inform the sink of the new configuration */
389 	auxch_tx(dev, dp->auxch, 8, DP_LINK_BW_SET, sink, 2);
390 }
391 
392 static void
393 dp_set_training_pattern(struct drm_device *dev, struct dp_state *dp, u8 tp)
394 {
395 	u8 sink_tp;
396 
397 	NV_DEBUG_KMS(dev, "training pattern %d\n", tp);
398 
399 	nv_mask(dev, NV50_SOR_DP_CTRL(dp->or, dp->link), 0x0f000000, tp << 24);
400 
401 	auxch_tx(dev, dp->auxch, 9, DP_TRAINING_PATTERN_SET, &sink_tp, 1);
402 	sink_tp &= ~DP_TRAINING_PATTERN_MASK;
403 	sink_tp |= tp;
404 	auxch_tx(dev, dp->auxch, 8, DP_TRAINING_PATTERN_SET, &sink_tp, 1);
405 }
406 
407 static const u8 nv50_lane_map[] = { 16, 8, 0, 24 };
408 static const u8 nvaf_lane_map[] = { 24, 16, 8, 0 };
409 
410 static int
411 dp_link_train_commit(struct drm_device *dev, struct dp_state *dp)
412 {
413 	struct drm_nouveau_private *dev_priv = dev->dev_private;
414 	u32 mask = 0, drv = 0, pre = 0, unk = 0;
415 	const u8 *shifts;
416 	int link = dp->link;
417 	int or = dp->or;
418 	int i;
419 
420 	if (dev_priv->chipset != 0xaf)
421 		shifts = nv50_lane_map;
422 	else
423 		shifts = nvaf_lane_map;
424 
425 	for (i = 0; i < dp->link_nr; i++) {
426 		u8 *conf = dp->entry + dp->table[4];
427 		u8 lane = (dp->stat[4 + (i >> 1)] >> ((i & 1) * 4)) & 0xf;
428 		u8 lpre = (lane & 0x0c) >> 2;
429 		u8 lvsw = (lane & 0x03) >> 0;
430 
431 		mask |= 0xff << shifts[i];
432 		unk |= 1 << (shifts[i] >> 3);
433 
434 		dp->conf[i] = (lpre << 3) | lvsw;
435 		if (lvsw == DP_TRAIN_VOLTAGE_SWING_1200)
436 			dp->conf[i] |= DP_TRAIN_MAX_SWING_REACHED;
437 		if (lpre == DP_TRAIN_PRE_EMPHASIS_9_5)
438 			dp->conf[i] |= DP_TRAIN_MAX_PRE_EMPHASIS_REACHED;
439 
440 		NV_DEBUG_KMS(dev, "config lane %d %02x\n", i, dp->conf[i]);
441 
442 		if (dp->table[0] < 0x30) {
443 			u8 *last = conf + (dp->entry[4] * dp->table[5]);
444 			while (lvsw != conf[0] || lpre != conf[1]) {
445 				conf += dp->table[5];
446 				if (conf >= last)
447 					return -EINVAL;
448 			}
449 
450 			conf += 2;
451 		} else {
452 			/* no lookup table anymore, set entries for each
453 			 * combination of voltage swing and pre-emphasis
454 			 * level allowed by the DP spec.
455 			 */
456 			switch (lvsw) {
457 			case 0: lpre += 0; break;
458 			case 1: lpre += 4; break;
459 			case 2: lpre += 7; break;
460 			case 3: lpre += 9; break;
461 			}
462 
463 			conf = conf + (lpre * dp->table[5]);
464 			conf++;
465 		}
466 
467 		drv |= conf[0] << shifts[i];
468 		pre |= conf[1] << shifts[i];
469 		unk  = (unk & ~0x0000ff00) | (conf[2] << 8);
470 	}
471 
472 	nv_mask(dev, NV50_SOR_DP_UNK118(or, link), mask, drv);
473 	nv_mask(dev, NV50_SOR_DP_UNK120(or, link), mask, pre);
474 	nv_mask(dev, NV50_SOR_DP_UNK130(or, link), 0x0000ff0f, unk);
475 
476 	return auxch_tx(dev, dp->auxch, 8, DP_TRAINING_LANE0_SET, dp->conf, 4);
477 }
478 
479 static int
480 dp_link_train_update(struct drm_device *dev, struct dp_state *dp, u32 delay)
481 {
482 	int ret;
483 
484 	udelay(delay);
485 
486 	ret = auxch_tx(dev, dp->auxch, 9, DP_LANE0_1_STATUS, dp->stat, 6);
487 	if (ret)
488 		return ret;
489 
490 	NV_DEBUG_KMS(dev, "status %02x %02x %02x %02x %02x %02x\n",
491 		     dp->stat[0], dp->stat[1], dp->stat[2], dp->stat[3],
492 		     dp->stat[4], dp->stat[5]);
493 	return 0;
494 }
495 
496 static int
497 dp_link_train_cr(struct drm_device *dev, struct dp_state *dp)
498 {
499 	bool cr_done = false, abort = false;
500 	int voltage = dp->conf[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
501 	int tries = 0, i;
502 
503 	dp_set_training_pattern(dev, dp, DP_TRAINING_PATTERN_1);
504 
505 	do {
506 		if (dp_link_train_commit(dev, dp) ||
507 		    dp_link_train_update(dev, dp, 100))
508 			break;
509 
510 		cr_done = true;
511 		for (i = 0; i < dp->link_nr; i++) {
512 			u8 lane = (dp->stat[i >> 1] >> ((i & 1) * 4)) & 0xf;
513 			if (!(lane & DP_LANE_CR_DONE)) {
514 				cr_done = false;
515 				if (dp->conf[i] & DP_TRAIN_MAX_SWING_REACHED)
516 					abort = true;
517 				break;
518 			}
519 		}
520 
521 		if ((dp->conf[0] & DP_TRAIN_VOLTAGE_SWING_MASK) != voltage) {
522 			voltage = dp->conf[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
523 			tries = 0;
524 		}
525 	} while (!cr_done && !abort && ++tries < 5);
526 
527 	return cr_done ? 0 : -1;
528 }
529 
530 static int
531 dp_link_train_eq(struct drm_device *dev, struct dp_state *dp)
532 {
533 	bool eq_done, cr_done = true;
534 	int tries = 0, i;
535 
536 	dp_set_training_pattern(dev, dp, DP_TRAINING_PATTERN_2);
537 
538 	do {
539 		if (dp_link_train_update(dev, dp, 400))
540 			break;
541 
542 		eq_done = !!(dp->stat[2] & DP_INTERLANE_ALIGN_DONE);
543 		for (i = 0; i < dp->link_nr && eq_done; i++) {
544 			u8 lane = (dp->stat[i >> 1] >> ((i & 1) * 4)) & 0xf;
545 			if (!(lane & DP_LANE_CR_DONE))
546 				cr_done = false;
547 			if (!(lane & DP_LANE_CHANNEL_EQ_DONE) ||
548 			    !(lane & DP_LANE_SYMBOL_LOCKED))
549 				eq_done = false;
550 		}
551 
552 		if (dp_link_train_commit(dev, dp))
553 			break;
554 	} while (!eq_done && cr_done && ++tries <= 5);
555 
556 	return eq_done ? 0 : -1;
557 }
558 
559 bool
560 nouveau_dp_link_train(struct drm_encoder *encoder, u32 datarate)
561 {
562 	struct drm_nouveau_private *dev_priv = encoder->dev->dev_private;
563 	struct nouveau_gpio_engine *pgpio = &dev_priv->engine.gpio;
564 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
565 	struct nouveau_crtc *nv_crtc = nouveau_crtc(encoder->crtc);
566 	struct nouveau_connector *nv_connector =
567 		nouveau_encoder_connector_get(nv_encoder);
568 	struct drm_device *dev = encoder->dev;
569 	struct nouveau_i2c_chan *auxch;
570 	const u32 bw_list[] = { 270000, 162000, 0 };
571 	const u32 *link_bw = bw_list;
572 	struct dp_state dp;
573 
574 	auxch = nouveau_i2c_find(dev, nv_encoder->dcb->i2c_index);
575 	if (!auxch)
576 		return false;
577 
578 	dp.table = nouveau_dp_bios_data(dev, nv_encoder->dcb, &dp.entry);
579 	if (!dp.table)
580 		return -EINVAL;
581 
582 	dp.dcb = nv_encoder->dcb;
583 	dp.crtc = nv_crtc->index;
584 	dp.auxch = auxch->rd;
585 	dp.or = nv_encoder->or;
586 	dp.link = !(nv_encoder->dcb->sorconf.link & 1);
587 	dp.dpcd = nv_encoder->dp.dpcd;
588 
589 	/* some sinks toggle hotplug in response to some of the actions
590 	 * we take during link training (DP_SET_POWER is one), we need
591 	 * to ignore them for the moment to avoid races.
592 	 */
593 	pgpio->irq_enable(dev, nv_connector->dcb->gpio_tag, false);
594 
595 	/* enable down-spreading, if possible */
596 	if (dp.table[1] >= 16) {
597 		u16 script = ROM16(dp.entry[14]);
598 		if (nv_encoder->dp.dpcd[3] & 1)
599 			script = ROM16(dp.entry[12]);
600 
601 		nouveau_bios_run_init_table(dev, script, dp.dcb, dp.crtc);
602 	}
603 
604 	/* execute pre-train script from vbios */
605 	nouveau_bios_run_init_table(dev, ROM16(dp.entry[6]), dp.dcb, dp.crtc);
606 
607 	/* start off at highest link rate supported by encoder and display */
608 	while (*link_bw > nv_encoder->dp.link_bw)
609 		link_bw++;
610 
611 	while (link_bw[0]) {
612 		/* find minimum required lane count at this link rate */
613 		dp.link_nr = nv_encoder->dp.link_nr;
614 		while ((dp.link_nr >> 1) * link_bw[0] > datarate)
615 			dp.link_nr >>= 1;
616 
617 		/* drop link rate to minimum with this lane count */
618 		while ((link_bw[1] * dp.link_nr) > datarate)
619 			link_bw++;
620 		dp.link_bw = link_bw[0];
621 
622 		/* program selected link configuration */
623 		dp_set_link_config(dev, &dp);
624 
625 		/* attempt to train the link at this configuration */
626 		memset(dp.stat, 0x00, sizeof(dp.stat));
627 		if (!dp_link_train_cr(dev, &dp) &&
628 		    !dp_link_train_eq(dev, &dp))
629 			break;
630 
631 		/* retry at lower rate */
632 		link_bw++;
633 	}
634 
635 	/* finish link training */
636 	dp_set_training_pattern(dev, &dp, DP_TRAINING_PATTERN_DISABLE);
637 
638 	/* execute post-train script from vbios */
639 	nouveau_bios_run_init_table(dev, ROM16(dp.entry[8]), dp.dcb, dp.crtc);
640 
641 	/* re-enable hotplug detect */
642 	pgpio->irq_enable(dev, nv_connector->dcb->gpio_tag, true);
643 	return true;
644 }
645 
646 bool
647 nouveau_dp_detect(struct drm_encoder *encoder)
648 {
649 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
650 	struct drm_device *dev = encoder->dev;
651 	struct nouveau_i2c_chan *auxch;
652 	u8 *dpcd = nv_encoder->dp.dpcd;
653 	int ret;
654 
655 	auxch = nouveau_i2c_find(dev, nv_encoder->dcb->i2c_index);
656 	if (!auxch)
657 		return false;
658 
659 	ret = auxch_tx(dev, auxch->rd, 9, DP_DPCD_REV, dpcd, 8);
660 	if (ret)
661 		return false;
662 
663 	nv_encoder->dp.link_bw = 27000 * dpcd[1];
664 	nv_encoder->dp.link_nr = dpcd[2] & DP_MAX_LANE_COUNT_MASK;
665 
666 	NV_DEBUG_KMS(dev, "display: %dx%d dpcd 0x%02x\n",
667 		     nv_encoder->dp.link_nr, nv_encoder->dp.link_bw, dpcd[0]);
668 	NV_DEBUG_KMS(dev, "encoder: %dx%d\n",
669 		     nv_encoder->dcb->dpconf.link_nr,
670 		     nv_encoder->dcb->dpconf.link_bw);
671 
672 	if (nv_encoder->dcb->dpconf.link_nr < nv_encoder->dp.link_nr)
673 		nv_encoder->dp.link_nr = nv_encoder->dcb->dpconf.link_nr;
674 	if (nv_encoder->dcb->dpconf.link_bw < nv_encoder->dp.link_bw)
675 		nv_encoder->dp.link_bw = nv_encoder->dcb->dpconf.link_bw;
676 
677 	NV_DEBUG_KMS(dev, "maximum: %dx%d\n",
678 		     nv_encoder->dp.link_nr, nv_encoder->dp.link_bw);
679 
680 	return true;
681 }
682 
683 int
684 nouveau_dp_auxch(struct nouveau_i2c_chan *auxch, int cmd, int addr,
685 		 uint8_t *data, int data_nr)
686 {
687 	return auxch_tx(auxch->dev, auxch->rd, cmd, addr, data, data_nr);
688 }
689 
690 static int
691 nouveau_dp_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
692 {
693 	struct nouveau_i2c_chan *auxch = (struct nouveau_i2c_chan *)adap;
694 	struct i2c_msg *msg = msgs;
695 	int ret, mcnt = num;
696 
697 	while (mcnt--) {
698 		u8 remaining = msg->len;
699 		u8 *ptr = msg->buf;
700 
701 		while (remaining) {
702 			u8 cnt = (remaining > 16) ? 16 : remaining;
703 			u8 cmd;
704 
705 			if (msg->flags & I2C_M_RD)
706 				cmd = AUX_I2C_READ;
707 			else
708 				cmd = AUX_I2C_WRITE;
709 
710 			if (mcnt || remaining > 16)
711 				cmd |= AUX_I2C_MOT;
712 
713 			ret = nouveau_dp_auxch(auxch, cmd, msg->addr, ptr, cnt);
714 			if (ret < 0)
715 				return ret;
716 
717 			ptr += cnt;
718 			remaining -= cnt;
719 		}
720 
721 		msg++;
722 	}
723 
724 	return num;
725 }
726 
727 static u32
728 nouveau_dp_i2c_func(struct i2c_adapter *adap)
729 {
730 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
731 }
732 
733 const struct i2c_algorithm nouveau_dp_i2c_algo = {
734 	.master_xfer = nouveau_dp_i2c_xfer,
735 	.functionality = nouveau_dp_i2c_func
736 };
737