linux/drivers/gpu/drm/nouveau/nouveau_dp.c - nest-guard/1.0/linux - Git at Google

 /*
  * Copyright 2009 Red Hat Inc.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice shall be included in
  * all copies or substantial portions of the Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  * OTHER DEALINGS IN THE SOFTWARE.
  *
  * Authors: Ben Skeggs
  */

 #include "drmP.h"

 #include "nouveau_drv.h"
 #include "nouveau_i2c.h"
 #include "nouveau_connector.h"
 #include "nouveau_encoder.h"

 static int
 auxch_rd(struct drm_encoder *encoder, int address, uint8_t *buf, int size)
 {
 	struct drm_device *dev = encoder->dev;
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_i2c_chan *auxch;
 	int ret;

 	auxch = nouveau_i2c_find(dev, nv_encoder->dcb->i2c_index);
 	if (!auxch)
 		return -ENODEV;

 	ret = nouveau_dp_auxch(auxch, 9, address, buf, size);
 	if (ret)
 		return ret;

 	return 0;
 }

 static int
 auxch_wr(struct drm_encoder *encoder, int address, uint8_t *buf, int size)
 {
 	struct drm_device *dev = encoder->dev;
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_i2c_chan *auxch;
 	int ret;

 	auxch = nouveau_i2c_find(dev, nv_encoder->dcb->i2c_index);
 	if (!auxch)
 		return -ENODEV;

 	ret = nouveau_dp_auxch(auxch, 8, address, buf, size);
 	return ret;
 }

 static int
 nouveau_dp_lane_count_set(struct drm_encoder *encoder, uint8_t cmd)
 {
 	struct drm_device *dev = encoder->dev;
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	uint32_t tmp;
 	int or = nv_encoder->or, link = !(nv_encoder->dcb->sorconf.link & 1);

 	tmp  = nv_rd32(dev, NV50_SOR_DP_CTRL(or, link));
 	tmp &= ~(NV50_SOR_DP_CTRL_ENHANCED_FRAME_ENABLED |
 		 NV50_SOR_DP_CTRL_LANE_MASK);
 	tmp |= ((1 << (cmd & DP_LANE_COUNT_MASK)) - 1) << 16;
 	if (cmd & DP_LANE_COUNT_ENHANCED_FRAME_EN)
 		tmp |= NV50_SOR_DP_CTRL_ENHANCED_FRAME_ENABLED;
 	nv_wr32(dev, NV50_SOR_DP_CTRL(or, link), tmp);

 	return auxch_wr(encoder, DP_LANE_COUNT_SET, &cmd, 1);
 }

 static int
 nouveau_dp_link_bw_set(struct drm_encoder *encoder, uint8_t cmd)
 {
 	struct drm_device *dev = encoder->dev;
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	uint32_t tmp;
 	int reg = 0x614300 + (nv_encoder->or * 0x800);

 	tmp  = nv_rd32(dev, reg);
 	tmp &= 0xfff3ffff;
 	if (cmd == DP_LINK_BW_2_7)
 		tmp |= 0x00040000;
 	nv_wr32(dev, reg, tmp);

 	return auxch_wr(encoder, DP_LINK_BW_SET, &cmd, 1);
 }

 static int
 nouveau_dp_link_train_set(struct drm_encoder *encoder, int pattern)
 {
 	struct drm_device *dev = encoder->dev;
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	uint32_t tmp;
 	uint8_t cmd;
 	int or = nv_encoder->or, link = !(nv_encoder->dcb->sorconf.link & 1);
 	int ret;

 	tmp  = nv_rd32(dev, NV50_SOR_DP_CTRL(or, link));
 	tmp &= ~NV50_SOR_DP_CTRL_TRAINING_PATTERN;
 	tmp |= (pattern << 24);
 	nv_wr32(dev, NV50_SOR_DP_CTRL(or, link), tmp);

 	ret = auxch_rd(encoder, DP_TRAINING_PATTERN_SET, &cmd, 1);
 	if (ret)
 		return ret;
 	cmd &= ~DP_TRAINING_PATTERN_MASK;
 	cmd |= (pattern & DP_TRAINING_PATTERN_MASK);
 	return auxch_wr(encoder, DP_TRAINING_PATTERN_SET, &cmd, 1);
 }

 static int
 nouveau_dp_max_voltage_swing(struct drm_encoder *encoder)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct drm_device *dev = encoder->dev;
 	struct bit_displayport_encoder_table_entry *dpse;
 	struct bit_displayport_encoder_table *dpe;
 	int i, dpe_headerlen, max_vs = 0;

 	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
 	if (!dpe)
 		return false;
 	dpse = (void *)((char *)dpe + dpe_headerlen);

 	for (i = 0; i < dpe_headerlen; i++, dpse++) {
 		if (dpse->vs_level > max_vs)
 			max_vs = dpse->vs_level;
 	}

 	return max_vs;
 }

 static int
 nouveau_dp_max_pre_emphasis(struct drm_encoder *encoder, int vs)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct drm_device *dev = encoder->dev;
 	struct bit_displayport_encoder_table_entry *dpse;
 	struct bit_displayport_encoder_table *dpe;
 	int i, dpe_headerlen, max_pre = 0;

 	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
 	if (!dpe)
 		return false;
 	dpse = (void *)((char *)dpe + dpe_headerlen);

 	for (i = 0; i < dpe_headerlen; i++, dpse++) {
 		if (dpse->vs_level != vs)
 			continue;

 		if (dpse->pre_level > max_pre)
 			max_pre = dpse->pre_level;
 	}

 	return max_pre;
 }

 static bool
 nouveau_dp_link_train_adjust(struct drm_encoder *encoder, uint8_t *config)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct drm_device *dev = encoder->dev;
 	struct bit_displayport_encoder_table_entry *dpse;
 	struct bit_displayport_encoder_table *dpe;
 	int ret, i, dpe_headerlen, vs = 0, pre = 0;
 	uint8_t request[2];

 	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
 	if (!dpe)
 		return false;
 	dpse = (void *)((char *)dpe + dpe_headerlen);

 	ret = auxch_rd(encoder, DP_ADJUST_REQUEST_LANE0_1, request, 2);
 	if (ret)
 		return false;

 	NV_DEBUG_KMS(dev, "\t\tadjust 0x%02x 0x%02x\n", request[0], request[1]);

 	/* Keep all lanes at the same level.. */
 	for (i = 0; i < nv_encoder->dp.link_nr; i++) {
 		int lane_req = (request[i >> 1] >> ((i & 1) << 2)) & 0xf;
 		int lane_vs = lane_req & 3;
 		int lane_pre = (lane_req >> 2) & 3;

 		if (lane_vs > vs)
 			vs = lane_vs;
 		if (lane_pre > pre)
 			pre = lane_pre;
 	}

 	if (vs >= nouveau_dp_max_voltage_swing(encoder)) {
 		vs  = nouveau_dp_max_voltage_swing(encoder);
 		vs |= 4;
 	}

 	if (pre >= nouveau_dp_max_pre_emphasis(encoder, vs & 3)) {
 		pre  = nouveau_dp_max_pre_emphasis(encoder, vs & 3);
 		pre |= 4;
 	}

 	/* Update the configuration for all lanes.. */
 	for (i = 0; i < nv_encoder->dp.link_nr; i++)
 		config[i] = (pre << 3) | vs;

 	return true;
 }

 static bool
 nouveau_dp_link_train_commit(struct drm_encoder *encoder, uint8_t *config)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct drm_device *dev = encoder->dev;
 	struct bit_displayport_encoder_table_entry *dpse;
 	struct bit_displayport_encoder_table *dpe;
 	int or = nv_encoder->or, link = !(nv_encoder->dcb->sorconf.link & 1);
 	int dpe_headerlen, ret, i;

 	NV_DEBUG_KMS(dev, "\t\tconfig 0x%02x 0x%02x 0x%02x 0x%02x\n",
 		 config[0], config[1], config[2], config[3]);

 	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
 	if (!dpe)
 		return false;
 	dpse = (void *)((char *)dpe + dpe_headerlen);

 	for (i = 0; i < dpe->record_nr; i++, dpse++) {
 		if (dpse->vs_level == (config[0] & 3) &&
 		    dpse->pre_level == ((config[0] >> 3) & 3))
 			break;
 	}
 	BUG_ON(i == dpe->record_nr);

 	for (i = 0; i < nv_encoder->dp.link_nr; i++) {
 		const int shift[4] = { 16, 8, 0, 24 };
 		uint32_t mask = 0xff << shift[i];
 		uint32_t reg0, reg1, reg2;

 		reg0  = nv_rd32(dev, NV50_SOR_DP_UNK118(or, link)) & ~mask;
 		reg0 |= (dpse->reg0 << shift[i]);
 		reg1  = nv_rd32(dev, NV50_SOR_DP_UNK120(or, link)) & ~mask;
 		reg1 |= (dpse->reg1 << shift[i]);
 		reg2  = nv_rd32(dev, NV50_SOR_DP_UNK130(or, link)) & 0xffff00ff;
 		reg2 |= (dpse->reg2 << 8);
 		nv_wr32(dev, NV50_SOR_DP_UNK118(or, link), reg0);
 		nv_wr32(dev, NV50_SOR_DP_UNK120(or, link), reg1);
 		nv_wr32(dev, NV50_SOR_DP_UNK130(or, link), reg2);
 	}

 	ret = auxch_wr(encoder, DP_TRAINING_LANE0_SET, config, 4);
 	if (ret)
 		return false;

 	return true;
 }

 bool
 nouveau_dp_link_train(struct drm_encoder *encoder)
 {
 	struct drm_device *dev = encoder->dev;
 	struct drm_nouveau_private *dev_priv = dev->dev_private;
 	struct nouveau_gpio_engine *pgpio = &dev_priv->engine.gpio;
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct nouveau_connector *nv_connector;
 	struct bit_displayport_encoder_table *dpe;
 	int dpe_headerlen;
 	uint8_t config[4], status[3];
 	bool cr_done, cr_max_vs, eq_done;
 	int ret = 0, i, tries, voltage;

 	NV_DEBUG_KMS(dev, "link training!!\n");

 	nv_connector = nouveau_encoder_connector_get(nv_encoder);
 	if (!nv_connector)
 		return false;

 	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
 	if (!dpe) {
 		NV_ERROR(dev, "SOR-%d: no DP encoder table!\n", nv_encoder->or);
 		return false;
 	}

 	/* disable hotplug detect, this flips around on some panels during
 	 * link training.
 	 */
 	pgpio->irq_enable(dev, nv_connector->dcb->gpio_tag, false);

 	if (dpe->script0) {
 		NV_DEBUG_KMS(dev, "SOR-%d: running DP script 0\n", nv_encoder->or);
 		nouveau_bios_run_init_table(dev, le16_to_cpu(dpe->script0),
 					    nv_encoder->dcb);
 	}

 train:
 	cr_done = eq_done = false;

 	/* set link configuration */
 	NV_DEBUG_KMS(dev, "\tbegin train: bw %d, lanes %d\n",
 		 nv_encoder->dp.link_bw, nv_encoder->dp.link_nr);

 	ret = nouveau_dp_link_bw_set(encoder, nv_encoder->dp.link_bw);
 	if (ret)
 		return false;

 	config[0] = nv_encoder->dp.link_nr;
 	if (nv_encoder->dp.dpcd_version >= 0x11 &&
 	    nv_encoder->dp.enhanced_frame)
 		config[0] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;

 	ret = nouveau_dp_lane_count_set(encoder, config[0]);
 	if (ret)
 		return false;

 	/* clock recovery */
 	NV_DEBUG_KMS(dev, "\tbegin cr\n");
 	ret = nouveau_dp_link_train_set(encoder, DP_TRAINING_PATTERN_1);
 	if (ret)
 		goto stop;

 	tries = 0;
 	voltage = -1;
 	memset(config, 0x00, sizeof(config));
 	for (;;) {
 		if (!nouveau_dp_link_train_commit(encoder, config))
 			break;

 		udelay(100);

 		ret = auxch_rd(encoder, DP_LANE0_1_STATUS, status, 2);
 		if (ret)
 			break;
 		NV_DEBUG_KMS(dev, "\t\tstatus: 0x%02x 0x%02x\n",
 			 status[0], status[1]);

 		cr_done = true;
 		cr_max_vs = false;
 		for (i = 0; i < nv_encoder->dp.link_nr; i++) {
 			int lane = (status[i >> 1] >> ((i & 1) * 4)) & 0xf;

 			if (!(lane & DP_LANE_CR_DONE)) {
 				cr_done = false;
 				if (config[i] & DP_TRAIN_MAX_PRE_EMPHASIS_REACHED)
 					cr_max_vs = true;
 				break;
 			}
 		}

 		if ((config[0] & DP_TRAIN_VOLTAGE_SWING_MASK) != voltage) {
 			voltage = config[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
 			tries = 0;
 		}

 		if (cr_done || cr_max_vs || (++tries == 5))
 			break;

 		if (!nouveau_dp_link_train_adjust(encoder, config))
 			break;
 	}

 	if (!cr_done)
 		goto stop;

 	/* channel equalisation */
 	NV_DEBUG_KMS(dev, "\tbegin eq\n");
 	ret = nouveau_dp_link_train_set(encoder, DP_TRAINING_PATTERN_2);
 	if (ret)
 		goto stop;

 	for (tries = 0; tries <= 5; tries++) {
 		udelay(400);

 		ret = auxch_rd(encoder, DP_LANE0_1_STATUS, status, 3);
 		if (ret)
 			break;
 		NV_DEBUG_KMS(dev, "\t\tstatus: 0x%02x 0x%02x\n",
 			 status[0], status[1]);

 		eq_done = true;
 		if (!(status[2] & DP_INTERLANE_ALIGN_DONE))
 			eq_done = false;

 		for (i = 0; eq_done && i < nv_encoder->dp.link_nr; i++) {
 			int lane = (status[i >> 1] >> ((i & 1) * 4)) & 0xf;

 			if (!(lane & DP_LANE_CR_DONE)) {
 				cr_done = false;
 				break;
 			}

 			if (!(lane & DP_LANE_CHANNEL_EQ_DONE) ||
 			    !(lane & DP_LANE_SYMBOL_LOCKED)) {
 				eq_done = false;
 				break;
 			}
 		}

 		if (eq_done || !cr_done)
 			break;

 		if (!nouveau_dp_link_train_adjust(encoder, config) ||
 		    !nouveau_dp_link_train_commit(encoder, config))
 			break;
 	}

 stop:
 	/* end link training */
 	ret = nouveau_dp_link_train_set(encoder, DP_TRAINING_PATTERN_DISABLE);
 	if (ret)
 		return false;

 	/* retry at a lower setting, if possible */
 	if (!ret && !(eq_done && cr_done)) {
 		NV_DEBUG_KMS(dev, "\twe failed\n");
 		if (nv_encoder->dp.link_bw != DP_LINK_BW_1_62) {
 			NV_DEBUG_KMS(dev, "retry link training at low rate\n");
 			nv_encoder->dp.link_bw = DP_LINK_BW_1_62;
 			goto train;
 		}
 	}

 	if (dpe->script1) {
 		NV_DEBUG_KMS(dev, "SOR-%d: running DP script 1\n", nv_encoder->or);
 		nouveau_bios_run_init_table(dev, le16_to_cpu(dpe->script1),
 					    nv_encoder->dcb);
 	}

 	/* re-enable hotplug detect */
 	pgpio->irq_enable(dev, nv_connector->dcb->gpio_tag, true);

 	return eq_done;
 }

 bool
 nouveau_dp_detect(struct drm_encoder *encoder)
 {
 	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
 	struct drm_device *dev = encoder->dev;
 	uint8_t dpcd[4];
 	int ret;

 	ret = auxch_rd(encoder, 0x0000, dpcd, 4);
 	if (ret)
 		return false;

 	NV_DEBUG_KMS(dev, "encoder: link_bw %d, link_nr %d\n"
 		      "display: link_bw %d, link_nr %d version 0x%02x\n",
 		 nv_encoder->dcb->dpconf.link_bw,
 		 nv_encoder->dcb->dpconf.link_nr,
 		 dpcd[1], dpcd[2] & 0x0f, dpcd[0]);

 	nv_encoder->dp.dpcd_version = dpcd[0];

 	nv_encoder->dp.link_bw = dpcd[1];
 	if (nv_encoder->dp.link_bw != DP_LINK_BW_1_62 &&
 	    !nv_encoder->dcb->dpconf.link_bw)
 		nv_encoder->dp.link_bw = DP_LINK_BW_1_62;

 	nv_encoder->dp.link_nr = dpcd[2] & DP_MAX_LANE_COUNT_MASK;
 	if (nv_encoder->dp.link_nr > nv_encoder->dcb->dpconf.link_nr)
 		nv_encoder->dp.link_nr = nv_encoder->dcb->dpconf.link_nr;

 	nv_encoder->dp.enhanced_frame = (dpcd[2] & DP_ENHANCED_FRAME_CAP);

 	return true;
 }

 int
 nouveau_dp_auxch(struct nouveau_i2c_chan *auxch, int cmd, int addr,
 		 uint8_t *data, int data_nr)
 {
 	struct drm_device *dev = auxch->dev;
 	uint32_t tmp, ctrl, stat = 0, data32[4] = {};
 	int ret = 0, i, index = auxch->rd;

 	NV_DEBUG_KMS(dev, "ch %d cmd %d addr 0x%x len %d\n", index, cmd, addr, data_nr);

 	tmp = nv_rd32(dev, NV50_AUXCH_CTRL(auxch->rd));
 	nv_wr32(dev, NV50_AUXCH_CTRL(auxch->rd), tmp | 0x00100000);
 	tmp = nv_rd32(dev, NV50_AUXCH_CTRL(auxch->rd));
 	if (!(tmp & 0x01000000)) {
 		NV_ERROR(dev, "expected bit 24 == 1, got 0x%08x\n", tmp);
 		ret = -EIO;
 		goto out;
 	}

 	for (i = 0; i < 3; i++) {
 		tmp = nv_rd32(dev, NV50_AUXCH_STAT(auxch->rd));
 		if (tmp & NV50_AUXCH_STAT_STATE_READY)
 			break;
 		udelay(100);
 	}

 	if (i == 3) {
 		ret = -EBUSY;
 		goto out;
 	}

 	if (!(cmd & 1)) {
 		memcpy(data32, data, data_nr);
 		for (i = 0; i < 4; i++) {
 			NV_DEBUG_KMS(dev, "wr %d: 0x%08x\n", i, data32[i]);
 			nv_wr32(dev, NV50_AUXCH_DATA_OUT(index, i), data32[i]);
 		}
 	}

 	nv_wr32(dev, NV50_AUXCH_ADDR(index), addr);
 	ctrl  = nv_rd32(dev, NV50_AUXCH_CTRL(index));
 	ctrl &= ~(NV50_AUXCH_CTRL_CMD | NV50_AUXCH_CTRL_LEN);
 	ctrl |= (cmd << NV50_AUXCH_CTRL_CMD_SHIFT);
 	ctrl |= ((data_nr - 1) << NV50_AUXCH_CTRL_LEN_SHIFT);

 	for (i = 0; i < 16; i++) {
 		nv_wr32(dev, NV50_AUXCH_CTRL(index), ctrl | 0x80000000);
 		nv_wr32(dev, NV50_AUXCH_CTRL(index), ctrl);
 		nv_wr32(dev, NV50_AUXCH_CTRL(index), ctrl | 0x00010000);
 		if (!nv_wait(dev, NV50_AUXCH_CTRL(index),
 			     0x00010000, 0x00000000)) {
 			NV_ERROR(dev, "expected bit 16 == 0, got 0x%08x\n",
 				 nv_rd32(dev, NV50_AUXCH_CTRL(index)));
 			ret = -EBUSY;
 			goto out;
 		}

 		udelay(400);

 		stat = nv_rd32(dev, NV50_AUXCH_STAT(index));
 		if ((stat & NV50_AUXCH_STAT_REPLY_AUX) !=
 			    NV50_AUXCH_STAT_REPLY_AUX_DEFER)
 			break;
 	}

 	if (i == 16) {
 		NV_ERROR(dev, "auxch DEFER too many times, bailing\n");
 		ret = -EREMOTEIO;
 		goto out;
 	}

 	if (cmd & 1) {
 		if ((stat & NV50_AUXCH_STAT_COUNT) != data_nr) {
 			ret = -EREMOTEIO;
 			goto out;
 		}

 		for (i = 0; i < 4; i++) {
 			data32[i] = nv_rd32(dev, NV50_AUXCH_DATA_IN(index, i));
 			NV_DEBUG_KMS(dev, "rd %d: 0x%08x\n", i, data32[i]);
 		}
 		memcpy(data, data32, data_nr);
 	}

 out:
 	tmp = nv_rd32(dev, NV50_AUXCH_CTRL(auxch->rd));
 	nv_wr32(dev, NV50_AUXCH_CTRL(auxch->rd), tmp & ~0x00100000);
 	tmp = nv_rd32(dev, NV50_AUXCH_CTRL(auxch->rd));
 	if (tmp & 0x01000000) {
 		NV_ERROR(dev, "expected bit 24 == 0, got 0x%08x\n", tmp);
 		ret = -EIO;
 	}

 	udelay(400);

 	return ret ? ret : (stat & NV50_AUXCH_STAT_REPLY);
 }

 static int
 nouveau_dp_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 {
 	struct nouveau_i2c_chan *auxch = (struct nouveau_i2c_chan *)adap;
 	struct drm_device *dev = auxch->dev;
 	struct i2c_msg *msg = msgs;
 	int ret, mcnt = num;

 	while (mcnt--) {
 		u8 remaining = msg->len;
 		u8 *ptr = msg->buf;

 		while (remaining) {
 			u8 cnt = (remaining > 16) ? 16 : remaining;
 			u8 cmd;

 			if (msg->flags & I2C_M_RD)
 				cmd = AUX_I2C_READ;
 			else
 				cmd = AUX_I2C_WRITE;

 			if (mcnt || remaining > 16)
 				cmd |= AUX_I2C_MOT;

 			ret = nouveau_dp_auxch(auxch, cmd, msg->addr, ptr, cnt);
 			if (ret < 0)
 				return ret;

 			switch (ret & NV50_AUXCH_STAT_REPLY_I2C) {
 			case NV50_AUXCH_STAT_REPLY_I2C_ACK:
 				break;
 			case NV50_AUXCH_STAT_REPLY_I2C_NACK:
 				return -EREMOTEIO;
 			case NV50_AUXCH_STAT_REPLY_I2C_DEFER:
 				udelay(100);
 				continue;
 			default:
 				NV_ERROR(dev, "bad auxch reply: 0x%08x\n", ret);
 				return -EREMOTEIO;
 			}

 			ptr += cnt;
 			remaining -= cnt;
 		}

 		msg++;
 	}

 	return num;
 }

 static u32
 nouveau_dp_i2c_func(struct i2c_adapter *adap)
 {
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
 }

 const struct i2c_algorithm nouveau_dp_i2c_algo = {
 	.master_xfer = nouveau_dp_i2c_xfer,
 	.functionality = nouveau_dp_i2c_func
 };
	/*
	* Copyright 2009 Red Hat Inc.
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice shall be included in
	* all copies or substantial portions of the Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
	* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
	* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
	* OTHER DEALINGS IN THE SOFTWARE.
	*
	* Authors: Ben Skeggs
	*/

	#include "drmP.h"

	#include "nouveau_drv.h"
	#include "nouveau_i2c.h"
	#include "nouveau_connector.h"
	#include "nouveau_encoder.h"

	static int
	auxch_rd(struct drm_encoder encoder, int address, uint8_t buf, int size)
	{
	struct drm_device *dev = encoder->dev;
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	struct nouveau_i2c_chan *auxch;
	int ret;

	auxch = nouveau_i2c_find(dev, nv_encoder->dcb->i2c_index);
	if (!auxch)
	return -ENODEV;

	ret = nouveau_dp_auxch(auxch, 9, address, buf, size);
	if (ret)
	return ret;

	return 0;
	}

	static int
	auxch_wr(struct drm_encoder encoder, int address, uint8_t buf, int size)
	{
	struct drm_device *dev = encoder->dev;
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	struct nouveau_i2c_chan *auxch;
	int ret;

	auxch = nouveau_i2c_find(dev, nv_encoder->dcb->i2c_index);
	if (!auxch)
	return -ENODEV;

	ret = nouveau_dp_auxch(auxch, 8, address, buf, size);
	return ret;
	}

	static int
	nouveau_dp_lane_count_set(struct drm_encoder *encoder, uint8_t cmd)
	{
	struct drm_device *dev = encoder->dev;
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	uint32_t tmp;
	int or = nv_encoder->or, link = !(nv_encoder->dcb->sorconf.link & 1);

	tmp = nv_rd32(dev, NV50_SOR_DP_CTRL(or, link));
	tmp &= ~(NV50_SOR_DP_CTRL_ENHANCED_FRAME_ENABLED \|
	NV50_SOR_DP_CTRL_LANE_MASK);
	tmp \|= ((1 << (cmd & DP_LANE_COUNT_MASK)) - 1) << 16;
	if (cmd & DP_LANE_COUNT_ENHANCED_FRAME_EN)
	tmp \|= NV50_SOR_DP_CTRL_ENHANCED_FRAME_ENABLED;
	nv_wr32(dev, NV50_SOR_DP_CTRL(or, link), tmp);

	return auxch_wr(encoder, DP_LANE_COUNT_SET, &cmd, 1);
	}

	static int
	nouveau_dp_link_bw_set(struct drm_encoder *encoder, uint8_t cmd)
	{
	struct drm_device *dev = encoder->dev;
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	uint32_t tmp;
	int reg = 0x614300 + (nv_encoder->or * 0x800);

	tmp = nv_rd32(dev, reg);
	tmp &= 0xfff3ffff;
	if (cmd == DP_LINK_BW_2_7)
	tmp \|= 0x00040000;
	nv_wr32(dev, reg, tmp);

	return auxch_wr(encoder, DP_LINK_BW_SET, &cmd, 1);
	}

	static int
	nouveau_dp_link_train_set(struct drm_encoder *encoder, int pattern)
	{
	struct drm_device *dev = encoder->dev;
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	uint32_t tmp;
	uint8_t cmd;
	int or = nv_encoder->or, link = !(nv_encoder->dcb->sorconf.link & 1);
	int ret;

	tmp = nv_rd32(dev, NV50_SOR_DP_CTRL(or, link));
	tmp &= ~NV50_SOR_DP_CTRL_TRAINING_PATTERN;
	tmp \|= (pattern << 24);
	nv_wr32(dev, NV50_SOR_DP_CTRL(or, link), tmp);

	ret = auxch_rd(encoder, DP_TRAINING_PATTERN_SET, &cmd, 1);
	if (ret)
	return ret;
	cmd &= ~DP_TRAINING_PATTERN_MASK;
	cmd \|= (pattern & DP_TRAINING_PATTERN_MASK);
	return auxch_wr(encoder, DP_TRAINING_PATTERN_SET, &cmd, 1);
	}

	static int
	nouveau_dp_max_voltage_swing(struct drm_encoder *encoder)
	{
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	struct drm_device *dev = encoder->dev;
	struct bit_displayport_encoder_table_entry *dpse;
	struct bit_displayport_encoder_table *dpe;
	int i, dpe_headerlen, max_vs = 0;

	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
	if (!dpe)
	return false;
	dpse = (void )((char )dpe + dpe_headerlen);

	for (i = 0; i < dpe_headerlen; i++, dpse++) {
	if (dpse->vs_level > max_vs)
	max_vs = dpse->vs_level;
	}

	return max_vs;
	}

	static int
	nouveau_dp_max_pre_emphasis(struct drm_encoder *encoder, int vs)
	{
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	struct drm_device *dev = encoder->dev;
	struct bit_displayport_encoder_table_entry *dpse;
	struct bit_displayport_encoder_table *dpe;
	int i, dpe_headerlen, max_pre = 0;

	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
	if (!dpe)
	return false;
	dpse = (void )((char )dpe + dpe_headerlen);

	for (i = 0; i < dpe_headerlen; i++, dpse++) {
	if (dpse->vs_level != vs)
	continue;

	if (dpse->pre_level > max_pre)
	max_pre = dpse->pre_level;
	}

	return max_pre;
	}

	static bool
	nouveau_dp_link_train_adjust(struct drm_encoder encoder, uint8_t config)
	{
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	struct drm_device *dev = encoder->dev;
	struct bit_displayport_encoder_table_entry *dpse;
	struct bit_displayport_encoder_table *dpe;
	int ret, i, dpe_headerlen, vs = 0, pre = 0;
	uint8_t request[2];

	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
	if (!dpe)
	return false;
	dpse = (void )((char )dpe + dpe_headerlen);

	ret = auxch_rd(encoder, DP_ADJUST_REQUEST_LANE0_1, request, 2);
	if (ret)
	return false;

	NV_DEBUG_KMS(dev, "\t\tadjust 0x%02x 0x%02x\n", request[0], request[1]);

	/* Keep all lanes at the same level.. */
	for (i = 0; i < nv_encoder->dp.link_nr; i++) {
	int lane_req = (request[i >> 1] >> ((i & 1) << 2)) & 0xf;
	int lane_vs = lane_req & 3;
	int lane_pre = (lane_req >> 2) & 3;

	if (lane_vs > vs)
	vs = lane_vs;
	if (lane_pre > pre)
	pre = lane_pre;
	}

	if (vs >= nouveau_dp_max_voltage_swing(encoder)) {
	vs = nouveau_dp_max_voltage_swing(encoder);
	vs \|= 4;
	}

	if (pre >= nouveau_dp_max_pre_emphasis(encoder, vs & 3)) {
	pre = nouveau_dp_max_pre_emphasis(encoder, vs & 3);
	pre \|= 4;
	}

	/* Update the configuration for all lanes.. */
	for (i = 0; i < nv_encoder->dp.link_nr; i++)
	config[i] = (pre << 3) \| vs;

	return true;
	}

	static bool
	nouveau_dp_link_train_commit(struct drm_encoder encoder, uint8_t config)
	{
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	struct drm_device *dev = encoder->dev;
	struct bit_displayport_encoder_table_entry *dpse;
	struct bit_displayport_encoder_table *dpe;
	int or = nv_encoder->or, link = !(nv_encoder->dcb->sorconf.link & 1);
	int dpe_headerlen, ret, i;

	NV_DEBUG_KMS(dev, "\t\tconfig 0x%02x 0x%02x 0x%02x 0x%02x\n",
	config[0], config[1], config[2], config[3]);

	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
	if (!dpe)
	return false;
	dpse = (void )((char )dpe + dpe_headerlen);

	for (i = 0; i < dpe->record_nr; i++, dpse++) {
	if (dpse->vs_level == (config[0] & 3) &&
	dpse->pre_level == ((config[0] >> 3) & 3))
	break;
	}
	BUG_ON(i == dpe->record_nr);

	for (i = 0; i < nv_encoder->dp.link_nr; i++) {
	const int shift[4] = { 16, 8, 0, 24 };
	uint32_t mask = 0xff << shift[i];
	uint32_t reg0, reg1, reg2;

	reg0 = nv_rd32(dev, NV50_SOR_DP_UNK118(or, link)) & ~mask;
	reg0 \|= (dpse->reg0 << shift[i]);
	reg1 = nv_rd32(dev, NV50_SOR_DP_UNK120(or, link)) & ~mask;
	reg1 \|= (dpse->reg1 << shift[i]);
	reg2 = nv_rd32(dev, NV50_SOR_DP_UNK130(or, link)) & 0xffff00ff;
	reg2 \|= (dpse->reg2 << 8);
	nv_wr32(dev, NV50_SOR_DP_UNK118(or, link), reg0);
	nv_wr32(dev, NV50_SOR_DP_UNK120(or, link), reg1);
	nv_wr32(dev, NV50_SOR_DP_UNK130(or, link), reg2);
	}

	ret = auxch_wr(encoder, DP_TRAINING_LANE0_SET, config, 4);
	if (ret)
	return false;

	return true;
	}

	bool
	nouveau_dp_link_train(struct drm_encoder *encoder)
	{
	struct drm_device *dev = encoder->dev;
	struct drm_nouveau_private *dev_priv = dev->dev_private;
	struct nouveau_gpio_engine *pgpio = &dev_priv->engine.gpio;
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	struct nouveau_connector *nv_connector;
	struct bit_displayport_encoder_table *dpe;
	int dpe_headerlen;
	uint8_t config[4], status[3];
	bool cr_done, cr_max_vs, eq_done;
	int ret = 0, i, tries, voltage;

	NV_DEBUG_KMS(dev, "link training!!\n");

	nv_connector = nouveau_encoder_connector_get(nv_encoder);
	if (!nv_connector)
	return false;

	dpe = nouveau_bios_dp_table(dev, nv_encoder->dcb, &dpe_headerlen);
	if (!dpe) {
	NV_ERROR(dev, "SOR-%d: no DP encoder table!\n", nv_encoder->or);
	return false;
	}

	/* disable hotplug detect, this flips around on some panels during
	* link training.
	*/
	pgpio->irq_enable(dev, nv_connector->dcb->gpio_tag, false);

	if (dpe->script0) {
	NV_DEBUG_KMS(dev, "SOR-%d: running DP script 0\n", nv_encoder->or);
	nouveau_bios_run_init_table(dev, le16_to_cpu(dpe->script0),
	nv_encoder->dcb);
	}

	train:
	cr_done = eq_done = false;

	/* set link configuration */
	NV_DEBUG_KMS(dev, "\tbegin train: bw %d, lanes %d\n",
	nv_encoder->dp.link_bw, nv_encoder->dp.link_nr);

	ret = nouveau_dp_link_bw_set(encoder, nv_encoder->dp.link_bw);
	if (ret)
	return false;

	config[0] = nv_encoder->dp.link_nr;
	if (nv_encoder->dp.dpcd_version >= 0x11 &&
	nv_encoder->dp.enhanced_frame)
	config[0] \|= DP_LANE_COUNT_ENHANCED_FRAME_EN;

	ret = nouveau_dp_lane_count_set(encoder, config[0]);
	if (ret)
	return false;

	/* clock recovery */
	NV_DEBUG_KMS(dev, "\tbegin cr\n");
	ret = nouveau_dp_link_train_set(encoder, DP_TRAINING_PATTERN_1);
	if (ret)
	goto stop;

	tries = 0;
	voltage = -1;
	memset(config, 0x00, sizeof(config));
	for (;;) {
	if (!nouveau_dp_link_train_commit(encoder, config))
	break;

	udelay(100);

	ret = auxch_rd(encoder, DP_LANE0_1_STATUS, status, 2);
	if (ret)
	break;
	NV_DEBUG_KMS(dev, "\t\tstatus: 0x%02x 0x%02x\n",
	status[0], status[1]);

	cr_done = true;
	cr_max_vs = false;
	for (i = 0; i < nv_encoder->dp.link_nr; i++) {
	int lane = (status[i >> 1] >> ((i & 1) * 4)) & 0xf;

	if (!(lane & DP_LANE_CR_DONE)) {
	cr_done = false;
	if (config[i] & DP_TRAIN_MAX_PRE_EMPHASIS_REACHED)
	cr_max_vs = true;
	break;
	}
	}

	if ((config[0] & DP_TRAIN_VOLTAGE_SWING_MASK) != voltage) {
	voltage = config[0] & DP_TRAIN_VOLTAGE_SWING_MASK;
	tries = 0;
	}

	if (cr_done \|\| cr_max_vs \|\| (++tries == 5))
	break;

	if (!nouveau_dp_link_train_adjust(encoder, config))
	break;
	}

	if (!cr_done)
	goto stop;

	/* channel equalisation */
	NV_DEBUG_KMS(dev, "\tbegin eq\n");
	ret = nouveau_dp_link_train_set(encoder, DP_TRAINING_PATTERN_2);
	if (ret)
	goto stop;

	for (tries = 0; tries <= 5; tries++) {
	udelay(400);

	ret = auxch_rd(encoder, DP_LANE0_1_STATUS, status, 3);
	if (ret)
	break;
	NV_DEBUG_KMS(dev, "\t\tstatus: 0x%02x 0x%02x\n",
	status[0], status[1]);

	eq_done = true;
	if (!(status[2] & DP_INTERLANE_ALIGN_DONE))
	eq_done = false;

	for (i = 0; eq_done && i < nv_encoder->dp.link_nr; i++) {
	int lane = (status[i >> 1] >> ((i & 1) * 4)) & 0xf;

	if (!(lane & DP_LANE_CR_DONE)) {
	cr_done = false;
	break;
	}

	if (!(lane & DP_LANE_CHANNEL_EQ_DONE) \|\|
	!(lane & DP_LANE_SYMBOL_LOCKED)) {
	eq_done = false;
	break;
	}
	}

	if (eq_done \|\| !cr_done)
	break;

	if (!nouveau_dp_link_train_adjust(encoder, config) \|\|
	!nouveau_dp_link_train_commit(encoder, config))
	break;
	}

	stop:
	/* end link training */
	ret = nouveau_dp_link_train_set(encoder, DP_TRAINING_PATTERN_DISABLE);
	if (ret)
	return false;

	/* retry at a lower setting, if possible */
	if (!ret && !(eq_done && cr_done)) {
	NV_DEBUG_KMS(dev, "\twe failed\n");
	if (nv_encoder->dp.link_bw != DP_LINK_BW_1_62) {
	NV_DEBUG_KMS(dev, "retry link training at low rate\n");
	nv_encoder->dp.link_bw = DP_LINK_BW_1_62;
	goto train;
	}
	}

	if (dpe->script1) {
	NV_DEBUG_KMS(dev, "SOR-%d: running DP script 1\n", nv_encoder->or);
	nouveau_bios_run_init_table(dev, le16_to_cpu(dpe->script1),
	nv_encoder->dcb);
	}

	/* re-enable hotplug detect */
	pgpio->irq_enable(dev, nv_connector->dcb->gpio_tag, true);

	return eq_done;
	}

	bool
	nouveau_dp_detect(struct drm_encoder *encoder)
	{
	struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
	struct drm_device *dev = encoder->dev;
	uint8_t dpcd[4];
	int ret;

	ret = auxch_rd(encoder, 0x0000, dpcd, 4);
	if (ret)
	return false;

	NV_DEBUG_KMS(dev, "encoder: link_bw %d, link_nr %d\n"
	"display: link_bw %d, link_nr %d version 0x%02x\n",
	nv_encoder->dcb->dpconf.link_bw,
	nv_encoder->dcb->dpconf.link_nr,
	dpcd[1], dpcd[2] & 0x0f, dpcd[0]);

	nv_encoder->dp.dpcd_version = dpcd[0];

	nv_encoder->dp.link_bw = dpcd[1];
	if (nv_encoder->dp.link_bw != DP_LINK_BW_1_62 &&
	!nv_encoder->dcb->dpconf.link_bw)
	nv_encoder->dp.link_bw = DP_LINK_BW_1_62;

	nv_encoder->dp.link_nr = dpcd[2] & DP_MAX_LANE_COUNT_MASK;
	if (nv_encoder->dp.link_nr > nv_encoder->dcb->dpconf.link_nr)
	nv_encoder->dp.link_nr = nv_encoder->dcb->dpconf.link_nr;

	nv_encoder->dp.enhanced_frame = (dpcd[2] & DP_ENHANCED_FRAME_CAP);

	return true;
	}

	int
	nouveau_dp_auxch(struct nouveau_i2c_chan *auxch, int cmd, int addr,
	uint8_t *data, int data_nr)
	{
	struct drm_device *dev = auxch->dev;
	uint32_t tmp, ctrl, stat = 0, data32[4] = {};
	int ret = 0, i, index = auxch->rd;

	NV_DEBUG_KMS(dev, "ch %d cmd %d addr 0x%x len %d\n", index, cmd, addr, data_nr);

	tmp = nv_rd32(dev, NV50_AUXCH_CTRL(auxch->rd));
	nv_wr32(dev, NV50_AUXCH_CTRL(auxch->rd), tmp \| 0x00100000);
	tmp = nv_rd32(dev, NV50_AUXCH_CTRL(auxch->rd));
	if (!(tmp & 0x01000000)) {
	NV_ERROR(dev, "expected bit 24 == 1, got 0x%08x\n", tmp);
	ret = -EIO;
	goto out;
	}

	for (i = 0; i < 3; i++) {
	tmp = nv_rd32(dev, NV50_AUXCH_STAT(auxch->rd));
	if (tmp & NV50_AUXCH_STAT_STATE_READY)
	break;
	udelay(100);
	}

	if (i == 3) {
	ret = -EBUSY;
	goto out;
	}

	if (!(cmd & 1)) {
	memcpy(data32, data, data_nr);
	for (i = 0; i < 4; i++) {
	NV_DEBUG_KMS(dev, "wr %d: 0x%08x\n", i, data32[i]);
	nv_wr32(dev, NV50_AUXCH_DATA_OUT(index, i), data32[i]);
	}
	}

	nv_wr32(dev, NV50_AUXCH_ADDR(index), addr);
	ctrl = nv_rd32(dev, NV50_AUXCH_CTRL(index));
	ctrl &= ~(NV50_AUXCH_CTRL_CMD \| NV50_AUXCH_CTRL_LEN);
	ctrl \|= (cmd << NV50_AUXCH_CTRL_CMD_SHIFT);
	ctrl \|= ((data_nr - 1) << NV50_AUXCH_CTRL_LEN_SHIFT);

	for (i = 0; i < 16; i++) {
	nv_wr32(dev, NV50_AUXCH_CTRL(index), ctrl \| 0x80000000);
	nv_wr32(dev, NV50_AUXCH_CTRL(index), ctrl);
	nv_wr32(dev, NV50_AUXCH_CTRL(index), ctrl \| 0x00010000);
	if (!nv_wait(dev, NV50_AUXCH_CTRL(index),
	0x00010000, 0x00000000)) {
	NV_ERROR(dev, "expected bit 16 == 0, got 0x%08x\n",
	nv_rd32(dev, NV50_AUXCH_CTRL(index)));
	ret = -EBUSY;
	goto out;
	}

	udelay(400);

	stat = nv_rd32(dev, NV50_AUXCH_STAT(index));
	if ((stat & NV50_AUXCH_STAT_REPLY_AUX) !=
	NV50_AUXCH_STAT_REPLY_AUX_DEFER)
	break;
	}

	if (i == 16) {
	NV_ERROR(dev, "auxch DEFER too many times, bailing\n");
	ret = -EREMOTEIO;
	goto out;
	}

	if (cmd & 1) {
	if ((stat & NV50_AUXCH_STAT_COUNT) != data_nr) {
	ret = -EREMOTEIO;
	goto out;
	}

	for (i = 0; i < 4; i++) {
	data32[i] = nv_rd32(dev, NV50_AUXCH_DATA_IN(index, i));
	NV_DEBUG_KMS(dev, "rd %d: 0x%08x\n", i, data32[i]);
	}
	memcpy(data, data32, data_nr);
	}

	out:
	tmp = nv_rd32(dev, NV50_AUXCH_CTRL(auxch->rd));
	nv_wr32(dev, NV50_AUXCH_CTRL(auxch->rd), tmp & ~0x00100000);
	tmp = nv_rd32(dev, NV50_AUXCH_CTRL(auxch->rd));
	if (tmp & 0x01000000) {
	NV_ERROR(dev, "expected bit 24 == 0, got 0x%08x\n", tmp);
	ret = -EIO;
	}

	udelay(400);

	return ret ? ret : (stat & NV50_AUXCH_STAT_REPLY);
	}

	static int
	nouveau_dp_i2c_xfer(struct i2c_adapter adap, struct i2c_msg msgs, int num)
	{
	struct nouveau_i2c_chan auxch = (struct nouveau_i2c_chan )adap;
	struct drm_device *dev = auxch->dev;
	struct i2c_msg *msg = msgs;
	int ret, mcnt = num;

	while (mcnt--) {
	u8 remaining = msg->len;
	u8 *ptr = msg->buf;

	while (remaining) {
	u8 cnt = (remaining > 16) ? 16 : remaining;
	u8 cmd;

	if (msg->flags & I2C_M_RD)
	cmd = AUX_I2C_READ;
	else
	cmd = AUX_I2C_WRITE;

	if (mcnt \|\| remaining > 16)
	cmd \|= AUX_I2C_MOT;

	ret = nouveau_dp_auxch(auxch, cmd, msg->addr, ptr, cnt);
	if (ret < 0)
	return ret;

	switch (ret & NV50_AUXCH_STAT_REPLY_I2C) {
	case NV50_AUXCH_STAT_REPLY_I2C_ACK:
	break;
	case NV50_AUXCH_STAT_REPLY_I2C_NACK:
	return -EREMOTEIO;
	case NV50_AUXCH_STAT_REPLY_I2C_DEFER:
	udelay(100);
	continue;
	default:
	NV_ERROR(dev, "bad auxch reply: 0x%08x\n", ret);
	return -EREMOTEIO;
	}

	ptr += cnt;
	remaining -= cnt;
	}

	msg++;
	}

	return num;
	}

	static u32
	nouveau_dp_i2c_func(struct i2c_adapter *adap)
	{
	return I2C_FUNC_I2C \| I2C_FUNC_SMBUS_EMUL;
	}

	const struct i2c_algorithm nouveau_dp_i2c_algo = {
	.master_xfer = nouveau_dp_i2c_xfer,
	.functionality = nouveau_dp_i2c_func
	};