Merge branch 'drm-next-3.15-wip' of git://people.freedesktop.org/~deathsimple/linux into drm-next

Some i2c fixes over DisplayPort.

* 'drm-next-3.15-wip' of git://people.freedesktop.org/~deathsimple/linux:
  drm/radeon: Improve vramlimit module param documentation
  drm/radeon: fix audio pin counts for DCE6+ (v2)
  drm/radeon/dp: switch to the common i2c over aux code
  drm/dp/i2c: Update comments about common i2c over dp assumptions (v3)
  drm/dp/i2c: send bare addresses to properly reset i2c connections (v4)
  drm/radeon/dp: handle zero sized i2c over aux transactions (v2)
  drm/i915: support address only i2c-over-aux transactions
  drm/tegra: dp: Support address-only I2C-over-AUX transactions

13 files changed, 152 insertions, 247 deletions

diff --git a/drivers/gpu/drm/drm_dp_helper.c b/drivers/gpu/drm/drm_dp_helper.c
index 27671489477d..4b6e6f3ba0a1 100644
--- a/drivers/gpu/drm/drm_dp_helper.c
+++ b/drivers/gpu/drm/drm_dp_helper.c
@@ -577,7 +577,9 @@ static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter)
 
 /*
  * Transfer a single I2C-over-AUX message and handle various error conditions,
- * retrying the transaction as appropriate.
+ * retrying the transaction as appropriate.  It is assumed that the
+ * aux->transfer function does not modify anything in the msg other than the
+ * reply field.
  */
 static int drm_dp_i2c_do_msg(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 {
@@ -665,11 +667,26 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
 {
 	struct drm_dp_aux *aux = adapter->algo_data;
 	unsigned int i, j;
+	struct drm_dp_aux_msg msg;
+	int err = 0;
 
-	for (i = 0; i < num; i++) {
-		struct drm_dp_aux_msg msg;
-		int err;
+	memset(&msg, 0, sizeof(msg));
 
+	for (i = 0; i < num; i++) {
+		msg.address = msgs[i].addr;
+		msg.request = (msgs[i].flags & I2C_M_RD) ?
+			DP_AUX_I2C_READ :
+			DP_AUX_I2C_WRITE;
+		msg.request |= DP_AUX_I2C_MOT;
+		/* Send a bare address packet to start the transaction.
+		 * Zero sized messages specify an address only (bare
+		 * address) transaction.
+		 */
+		msg.buffer = NULL;
+		msg.size = 0;
+		err = drm_dp_i2c_do_msg(aux, &msg);
+		if (err < 0)
+			break;
 		/*
 		 * Many hardware implementations support FIFOs larger than a
 		 * single byte, but it has been empirically determined that
@@ -678,30 +695,28 @@ static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
 		 * transferred byte-by-byte.
 		 */
 		for (j = 0; j < msgs[i].len; j++) {
-			memset(&msg, 0, sizeof(msg));
-			msg.address = msgs[i].addr;
-
-			msg.request = (msgs[i].flags & I2C_M_RD) ?
-					DP_AUX_I2C_READ :
-					DP_AUX_I2C_WRITE;
-
-			/*
-			 * All messages except the last one are middle-of-
-			 * transfer messages.
-			 */
-			if ((i < num - 1) || (j < msgs[i].len - 1))
-				msg.request |= DP_AUX_I2C_MOT;
-
 			msg.buffer = msgs[i].buf + j;
 			msg.size = 1;
 
 			err = drm_dp_i2c_do_msg(aux, &msg);
 			if (err < 0)
-				return err;
+				break;
 		}
+		if (err < 0)
+			break;
 	}
+	if (err >= 0)
+		err = num;
+	/* Send a bare address packet to close out the transaction.
+	 * Zero sized messages specify an address only (bare
+	 * address) transaction.
+	 */
+	msg.request &= ~DP_AUX_I2C_MOT;
+	msg.buffer = NULL;
+	msg.size = 0;
+	(void)drm_dp_i2c_do_msg(aux, &msg);
 
-	return num;
+	return err;
 }
 
 static const struct i2c_algorithm drm_dp_i2c_algo = {
diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
index a0dad1a2f819..d2a55884ad52 100644
--- a/drivers/gpu/drm/i915/intel_dp.c
+++ b/drivers/gpu/drm/i915/intel_dp.c
@@ -575,7 +575,8 @@ out:
 	return ret;
 }
 
-#define HEADER_SIZE	4
+#define BARE_ADDRESS_SIZE	3
+#define HEADER_SIZE		(BARE_ADDRESS_SIZE + 1)
 static ssize_t
 intel_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 {
@@ -592,7 +593,7 @@ intel_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 	switch (msg->request & ~DP_AUX_I2C_MOT) {
 	case DP_AUX_NATIVE_WRITE:
 	case DP_AUX_I2C_WRITE:
-		txsize = HEADER_SIZE + msg->size;
+		txsize = msg->size ? HEADER_SIZE + msg->size : BARE_ADDRESS_SIZE;
 		rxsize = 1;
 
 		if (WARN_ON(txsize > 20))
@@ -611,7 +612,7 @@ intel_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 
 	case DP_AUX_NATIVE_READ:
 	case DP_AUX_I2C_READ:
-		txsize = HEADER_SIZE;
+		txsize = msg->size ? HEADER_SIZE : BARE_ADDRESS_SIZE;
 		rxsize = msg->size + 1;
 
 		if (WARN_ON(rxsize > 20))
diff --git a/drivers/gpu/drm/radeon/atombios_dp.c b/drivers/gpu/drm/radeon/atombios_dp.c
index 8b0ab170cef9..15936524f226 100644
--- a/drivers/gpu/drm/radeon/atombios_dp.c
+++ b/drivers/gpu/drm/radeon/atombios_dp.c
@@ -142,7 +142,8 @@ static int radeon_process_aux_ch(struct radeon_i2c_chan *chan,
 	return recv_bytes;
 }
 
-#define HEADER_SIZE 4
+#define BARE_ADDRESS_SIZE 3
+#define HEADER_SIZE (BARE_ADDRESS_SIZE + 1)
 
 static ssize_t
 radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
@@ -160,13 +161,19 @@ radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 	tx_buf[0] = msg->address & 0xff;
 	tx_buf[1] = msg->address >> 8;
 	tx_buf[2] = msg->request << 4;
-	tx_buf[3] = msg->size - 1;
+	tx_buf[3] = msg->size ? (msg->size - 1) : 0;
 
 	switch (msg->request & ~DP_AUX_I2C_MOT) {
 	case DP_AUX_NATIVE_WRITE:
 	case DP_AUX_I2C_WRITE:
+		/* tx_size needs to be 4 even for bare address packets since the atom
+		 * table needs the info in tx_buf[3].
+		 */
 		tx_size = HEADER_SIZE + msg->size;
-		tx_buf[3] |= tx_size << 4;
+		if (msg->size == 0)
+			tx_buf[3] |= BARE_ADDRESS_SIZE << 4;
+		else
+			tx_buf[3] |= tx_size << 4;
 		memcpy(tx_buf + HEADER_SIZE, msg->buffer, msg->size);
 		ret = radeon_process_aux_ch(chan,
 					    tx_buf, tx_size, NULL, 0, delay, &ack);
@@ -176,8 +183,14 @@ radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 		break;
 	case DP_AUX_NATIVE_READ:
 	case DP_AUX_I2C_READ:
+		/* tx_size needs to be 4 even for bare address packets since the atom
+		 * table needs the info in tx_buf[3].
+		 */
 		tx_size = HEADER_SIZE;
-		tx_buf[3] |= tx_size << 4;
+		if (msg->size == 0)
+			tx_buf[3] |= BARE_ADDRESS_SIZE << 4;
+		else
+			tx_buf[3] |= tx_size << 4;
 		ret = radeon_process_aux_ch(chan,
 					    tx_buf, tx_size, msg->buffer, msg->size, delay, &ack);
 		break;
@@ -186,7 +199,7 @@ radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 		break;
 	}
 
-	if (ret > 0)
+	if (ret >= 0)
 		msg->reply = ack >> 4;
 
 	return ret;
@@ -194,98 +207,15 @@ radeon_dp_aux_transfer(struct drm_dp_aux *aux, struct drm_dp_aux_msg *msg)
 
 void radeon_dp_aux_init(struct radeon_connector *radeon_connector)
 {
-	struct radeon_connector_atom_dig *dig_connector = radeon_connector->con_priv;
-
-	dig_connector->dp_i2c_bus->aux.dev = radeon_connector->base.kdev;
-	dig_connector->dp_i2c_bus->aux.transfer = radeon_dp_aux_transfer;
-}
-
-int radeon_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode,
-			 u8 write_byte, u8 *read_byte)
-{
-	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
-	struct radeon_i2c_chan *auxch = i2c_get_adapdata(adapter);
-	u16 address = algo_data->address;
-	u8 msg[5];
-	u8 reply[2];
-	unsigned retry;
-	int msg_bytes;
-	int reply_bytes = 1;
 	int ret;
-	u8 ack;
-
-	/* Set up the address */
-	msg[0] = address;
-	msg[1] = address >> 8;
-
-	/* Set up the command byte */
-	if (mode & MODE_I2C_READ) {
-		msg[2] = DP_AUX_I2C_READ << 4;
-		msg_bytes = 4;
-		msg[3] = msg_bytes << 4;
-	} else {
-		msg[2] = DP_AUX_I2C_WRITE << 4;
-		msg_bytes = 5;
-		msg[3] = msg_bytes << 4;
-		msg[4] = write_byte;
-	}
-
-	/* special handling for start/stop */
-	if (mode & (MODE_I2C_START | MODE_I2C_STOP))
-		msg[3] = 3 << 4;
-
-	/* Set MOT bit for all but stop */
-	if ((mode & MODE_I2C_STOP) == 0)
-		msg[2] |= DP_AUX_I2C_MOT << 4;
-
-	for (retry = 0; retry < 7; retry++) {
-		ret = radeon_process_aux_ch(auxch,
-					    msg, msg_bytes, reply, reply_bytes, 0, &ack);
-		if (ret == -EBUSY)
-			continue;
-		else if (ret < 0) {
-			DRM_DEBUG_KMS("aux_ch failed %d\n", ret);
-			return ret;
-		}
-
-		switch ((ack >> 4) & DP_AUX_NATIVE_REPLY_MASK) {
-		case DP_AUX_NATIVE_REPLY_ACK:
-			/* I2C-over-AUX Reply field is only valid
-			 * when paired with AUX ACK.
-			 */
-			break;
-		case DP_AUX_NATIVE_REPLY_NACK:
-			DRM_DEBUG_KMS("aux_ch native nack\n");
-			return -EREMOTEIO;
-		case DP_AUX_NATIVE_REPLY_DEFER:
-			DRM_DEBUG_KMS("aux_ch native defer\n");
-			usleep_range(500, 600);
-			continue;
-		default:
-			DRM_ERROR("aux_ch invalid native reply 0x%02x\n", ack);
-			return -EREMOTEIO;
-		}
 
-		switch ((ack >> 4) & DP_AUX_I2C_REPLY_MASK) {
-		case DP_AUX_I2C_REPLY_ACK:
-			if (mode == MODE_I2C_READ)
-				*read_byte = reply[0];
-			return ret;
-		case DP_AUX_I2C_REPLY_NACK:
-			DRM_DEBUG_KMS("aux_i2c nack\n");
-			return -EREMOTEIO;
-		case DP_AUX_I2C_REPLY_DEFER:
-			DRM_DEBUG_KMS("aux_i2c defer\n");
-			usleep_range(400, 500);
-			break;
-		default:
-			DRM_ERROR("aux_i2c invalid reply 0x%02x\n", ack);
-			return -EREMOTEIO;
-		}
-	}
+	radeon_connector->ddc_bus->aux.dev = radeon_connector->base.kdev;
+	radeon_connector->ddc_bus->aux.transfer = radeon_dp_aux_transfer;
+	ret = drm_dp_aux_register_i2c_bus(&radeon_connector->ddc_bus->aux);
+	if (!ret)
+		radeon_connector->ddc_bus->has_aux = true;
 
-	DRM_DEBUG_KMS("aux i2c too many retries, giving up\n");
-	return -EREMOTEIO;
+	WARN(ret, "drm_dp_aux_register_i2c_bus() failed with error %d\n", ret);
 }
 
 /***** general DP utility functions *****/
@@ -420,12 +350,11 @@ static u8 radeon_dp_encoder_service(struct radeon_device *rdev,
 
 u8 radeon_dp_getsinktype(struct radeon_connector *radeon_connector)
 {
-	struct radeon_connector_atom_dig *dig_connector = radeon_connector->con_priv;
 	struct drm_device *dev = radeon_connector->base.dev;
 	struct radeon_device *rdev = dev->dev_private;
 
 	return radeon_dp_encoder_service(rdev, ATOM_DP_ACTION_GET_SINK_TYPE, 0,
-					 dig_connector->dp_i2c_bus->rec.i2c_id, 0);
+					 radeon_connector->ddc_bus->rec.i2c_id, 0);
 }
 
 static void radeon_dp_probe_oui(struct radeon_connector *radeon_connector)
@@ -436,11 +365,11 @@ static void radeon_dp_probe_oui(struct radeon_connector *radeon_connector)
 	if (!(dig_connector->dpcd[DP_DOWN_STREAM_PORT_COUNT] & DP_OUI_SUPPORT))
 		return;
 
-	if (drm_dp_dpcd_read(&dig_connector->dp_i2c_bus->aux, DP_SINK_OUI, buf, 3))
+	if (drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_SINK_OUI, buf, 3))
 		DRM_DEBUG_KMS("Sink OUI: %02hx%02hx%02hx\n",
 			      buf[0], buf[1], buf[2]);
 
-	if (drm_dp_dpcd_read(&dig_connector->dp_i2c_bus->aux, DP_BRANCH_OUI, buf, 3))
+	if (drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_BRANCH_OUI, buf, 3))
 		DRM_DEBUG_KMS("Branch OUI: %02hx%02hx%02hx\n",
 			      buf[0], buf[1], buf[2]);
 }
@@ -451,7 +380,7 @@ bool radeon_dp_getdpcd(struct radeon_connector *radeon_connector)
 	u8 msg[DP_DPCD_SIZE];
 	int ret, i;
 
-	ret = drm_dp_dpcd_read(&dig_connector->dp_i2c_bus->aux, DP_DPCD_REV, msg,
+	ret = drm_dp_dpcd_read(&radeon_connector->ddc_bus->aux, DP_DPCD_REV, msg,
 			       DP_DPCD_SIZE);
 	if (ret > 0) {
 		memcpy(dig_connector->dpcd, msg, DP_DPCD_SIZE);
@@ -489,7 +418,7 @@ int radeon_dp_get_panel_mode(struct drm_encoder *encoder,
 
 	if (dp_bridge != ENCODER_OBJECT_ID_NONE) {
 		/* DP bridge chips */
-		drm_dp_dpcd_readb(&dig_connector->dp_i2c_bus->aux,
+		drm_dp_dpcd_readb(&radeon_connector->ddc_bus->aux,
 				  DP_EDP_CONFIGURATION_CAP, &tmp);
 		if (tmp & 1)
 			panel_mode = DP_PANEL_MODE_INTERNAL_DP2_MODE;
@@ -500,7 +429,7 @@ int radeon_dp_get_panel_mode(struct drm_encoder *encoder,
 			panel_mode = DP_PANEL_MODE_EXTERNAL_DP_MODE;
 	} else if (connector->connector_type == DRM_MODE_CONNECTOR_eDP) {
 		/* eDP */
-		drm_dp_dpcd_readb(&dig_connector->dp_i2c_bus->aux,
+		drm_dp_dpcd_readb(&radeon_connector->ddc_bus->aux,
 				  DP_EDP_CONFIGURATION_CAP, &tmp);
 		if (tmp & 1)
 			panel_mode = DP_PANEL_MODE_INTERNAL_DP2_MODE;
@@ -554,7 +483,8 @@ bool radeon_dp_needs_link_train(struct radeon_connector *radeon_connector)
 	u8 link_status[DP_LINK_STATUS_SIZE];
 	struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
 
-	if (drm_dp_dpcd_read_link_status(&dig->dp_i2c_bus->aux, link_status) <= 0)
+	if (drm_dp_dpcd_read_link_status(&radeon_connector->ddc_bus->aux, link_status)
+	    <= 0)
 		return false;
 	if (drm_dp_channel_eq_ok(link_status, dig->dp_lane_count))
 		return false;
@@ -574,7 +504,7 @@ void radeon_dp_set_rx_power_state(struct drm_connector *connector,
 
 	/* power up/down the sink */
 	if (dig_connector->dpcd[0] >= 0x11) {
-		drm_dp_dpcd_writeb(&dig_connector->dp_i2c_bus->aux,
+		drm_dp_dpcd_writeb(&radeon_connector->ddc_bus->aux,
 				   DP_SET_POWER, power_state);
 		usleep_range(1000, 2000);
 	}
@@ -878,7 +808,7 @@ void radeon_dp_link_train(struct drm_encoder *encoder,
 	else
 		dp_info.enc_id |= ATOM_DP_CONFIG_LINK_A;
 
-	drm_dp_dpcd_readb(&dig_connector->dp_i2c_bus->aux, DP_MAX_LANE_COUNT, &tmp);
+	drm_dp_dpcd_readb(&radeon_connector->ddc_bus->aux, DP_MAX_LANE_COUNT, &tmp);
 	if (ASIC_IS_DCE5(rdev) && (tmp & DP_TPS3_SUPPORTED))
 		dp_info.tp3_supported = true;
 	else
@@ -890,7 +820,7 @@ void radeon_dp_link_train(struct drm_encoder *encoder,
 	dp_info.connector = connector;
 	dp_info.dp_lane_count = dig_connector->dp_lane_count;
 	dp_info.dp_clock = dig_connector->dp_clock;
-	dp_info.aux = &dig_connector->dp_i2c_bus->aux;
+	dp_info.aux = &radeon_connector->ddc_bus->aux;
 
 	if (radeon_dp_link_train_init(&dp_info))
 		goto done;
diff --git a/drivers/gpu/drm/radeon/dce6_afmt.c b/drivers/gpu/drm/radeon/dce6_afmt.c
index 94e858751994..0a65dc7e93e7 100644
--- a/drivers/gpu/drm/radeon/dce6_afmt.c
+++ b/drivers/gpu/drm/radeon/dce6_afmt.c
@@ -309,11 +309,17 @@ int dce6_audio_init(struct radeon_device *rdev)
 
 	rdev->audio.enabled = true;
 
-	if (ASIC_IS_DCE8(rdev))
+	if (ASIC_IS_DCE81(rdev)) /* KV: 4 streams, 7 endpoints */
+		rdev->audio.num_pins = 7;
+	else if (ASIC_IS_DCE83(rdev)) /* KB: 2 streams, 3 endpoints */
+		rdev->audio.num_pins = 3;
+	else if (ASIC_IS_DCE8(rdev)) /* BN/HW: 6 streams, 7 endpoints */
+		rdev->audio.num_pins = 7;
+	else if (ASIC_IS_DCE61(rdev)) /* TN: 4 streams, 6 endpoints */
 		rdev->audio.num_pins = 6;
-	else if (ASIC_IS_DCE61(rdev))
-		rdev->audio.num_pins = 4;
-	else
+	else if (ASIC_IS_DCE64(rdev)) /* OL: 2 streams, 2 endpoints */
+		rdev->audio.num_pins = 2;
+	else /* SI: 6 streams, 6 endpoints */
 		rdev->audio.num_pins = 6;
 
 	for (i = 0; i < rdev->audio.num_pins; i++) {
diff --git a/drivers/gpu/drm/radeon/radeon.h b/drivers/gpu/drm/radeon/radeon.h
index 7014bdd688ce..b58e1afdda76 100644
--- a/drivers/gpu/drm/radeon/radeon.h
+++ b/drivers/gpu/drm/radeon/radeon.h
@@ -739,7 +739,7 @@ union radeon_irq_stat_regs {
 	struct cik_irq_stat_regs cik;
 };
 
-#define RADEON_MAX_HPD_PINS 6
+#define RADEON_MAX_HPD_PINS 7
 #define RADEON_MAX_CRTCS 6
 #define RADEON_MAX_AFMT_BLOCKS 7
 
@@ -2632,6 +2632,9 @@ void r100_pll_errata_after_index(struct radeon_device *rdev);
 #define ASIC_IS_DCE64(rdev) ((rdev->family == CHIP_OLAND))
 #define ASIC_IS_NODCE(rdev) ((rdev->family == CHIP_HAINAN))
 #define ASIC_IS_DCE8(rdev) ((rdev->family >= CHIP_BONAIRE))
+#define ASIC_IS_DCE81(rdev) ((rdev->family == CHIP_KAVERI))
+#define ASIC_IS_DCE82(rdev) ((rdev->family == CHIP_BONAIRE))
+#define ASIC_IS_DCE83(rdev) ((rdev->family == CHIP_KABINI))
 
 #define ASIC_IS_LOMBOK(rdev) ((rdev->ddev->pdev->device == 0x6849) || \
 			      (rdev->ddev->pdev->device == 0x6850) || \
diff --git a/drivers/gpu/drm/radeon/radeon_connectors.c b/drivers/gpu/drm/radeon/radeon_connectors.c
index c566b486ca08..ea50e0ae7bf7 100644
--- a/drivers/gpu/drm/radeon/radeon_connectors.c
+++ b/drivers/gpu/drm/radeon/radeon_connectors.c
@@ -1261,21 +1261,6 @@ static const struct drm_connector_funcs radeon_dvi_connector_funcs = {
 	.force = radeon_dvi_force,
 };
 
-static void radeon_dp_connector_destroy(struct drm_connector *connector)
-{
-	struct radeon_connector *radeon_connector = to_radeon_connector(connector);
-	struct radeon_connector_atom_dig *radeon_dig_connector = radeon_connector->con_priv;
-
-	if (radeon_connector->edid)
-		kfree(radeon_connector->edid);
-	if (radeon_dig_connector->dp_i2c_bus)
-		radeon_i2c_destroy(radeon_dig_connector->dp_i2c_bus);
-	kfree(radeon_connector->con_priv);
-	drm_sysfs_connector_remove(connector);
-	drm_connector_cleanup(connector);
-	kfree(connector);
-}
-
 static int radeon_dp_get_modes(struct drm_connector *connector)
 {
 	struct radeon_connector *radeon_connector = to_radeon_connector(connector);
@@ -1553,7 +1538,7 @@ static const struct drm_connector_funcs radeon_dp_connector_funcs = {
 	.detect = radeon_dp_detect,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.set_property = radeon_connector_set_property,
-	.destroy = radeon_dp_connector_destroy,
+	.destroy = radeon_connector_destroy,
 	.force = radeon_dvi_force,
 };
 
@@ -1562,7 +1547,7 @@ static const struct drm_connector_funcs radeon_edp_connector_funcs = {
 	.detect = radeon_dp_detect,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.set_property = radeon_lvds_set_property,
-	.destroy = radeon_dp_connector_destroy,
+	.destroy = radeon_connector_destroy,
 	.force = radeon_dvi_force,
 };
 
@@ -1571,7 +1556,7 @@ static const struct drm_connector_funcs radeon_lvds_bridge_connector_funcs = {
 	.detect = radeon_dp_detect,
 	.fill_modes = drm_helper_probe_single_connector_modes,
 	.set_property = radeon_lvds_set_property,
-	.destroy = radeon_dp_connector_destroy,
+	.destroy = radeon_connector_destroy,
 	.force = radeon_dvi_force,
 };
 
@@ -1668,17 +1653,10 @@ radeon_add_atom_connector(struct drm_device *dev,
 		radeon_dig_connector->igp_lane_info = igp_lane_info;
 		radeon_connector->con_priv = radeon_dig_connector;
 		if (i2c_bus->valid) {
-			/* add DP i2c bus */
-			if (connector_type == DRM_MODE_CONNECTOR_eDP)
-				radeon_dig_connector->dp_i2c_bus = radeon_i2c_create_dp(dev, i2c_bus, "eDP-auxch");
-			else
-				radeon_dig_connector->dp_i2c_bus = radeon_i2c_create_dp(dev, i2c_bus, "DP-auxch");
-			if (radeon_dig_connector->dp_i2c_bus)
+			radeon_connector->ddc_bus = radeon_i2c_lookup(rdev, i2c_bus);
+			if (radeon_connector->ddc_bus)
 				has_aux = true;
 			else
-				DRM_ERROR("DP: Failed to assign dp ddc bus! Check dmesg for i2c errors.\n");
-			radeon_connector->ddc_bus = radeon_i2c_lookup(rdev, i2c_bus);
-			if (!radeon_connector->ddc_bus)
 				DRM_ERROR("DP: Failed to assign ddc bus! Check dmesg for i2c errors.\n");
 		}
 		switch (connector_type) {
@@ -1893,10 +1871,6 @@ radeon_add_atom_connector(struct drm_device *dev,
 			drm_connector_init(dev, &radeon_connector->base, &radeon_dp_connector_funcs, connector_type);
 			drm_connector_helper_add(&radeon_connector->base, &radeon_dp_connector_helper_funcs);
 			if (i2c_bus->valid) {
-				/* add DP i2c bus */
-				radeon_dig_connector->dp_i2c_bus = radeon_i2c_create_dp(dev, i2c_bus, "DP-auxch");
-				if (!radeon_dig_connector->dp_i2c_bus)
-					DRM_ERROR("DP: Failed to assign dp ddc bus! Check dmesg for i2c errors.\n");
 				radeon_connector->ddc_bus = radeon_i2c_lookup(rdev, i2c_bus);
 				if (radeon_connector->ddc_bus)
 					has_aux = true;
@@ -1942,14 +1916,10 @@ radeon_add_atom_connector(struct drm_device *dev,
 			drm_connector_init(dev, &radeon_connector->base, &radeon_edp_connector_funcs, connector_type);
 			drm_connector_helper_add(&radeon_connector->base, &radeon_dp_connector_helper_funcs);
 			if (i2c_bus->valid) {
-				/* add DP i2c bus */
-				radeon_dig_connector->dp_i2c_bus = radeon_i2c_create_dp(dev, i2c_bus, "eDP-auxch");
-				if (radeon_dig_connector->dp_i2c_bus)
+				radeon_connector->ddc_bus = radeon_i2c_lookup(rdev, i2c_bus);
+				if (radeon_connector->ddc_bus)
 					has_aux = true;
 				else
-					DRM_ERROR("DP: Failed to assign dp ddc bus! Check dmesg for i2c errors.\n");
-				radeon_connector->ddc_bus = radeon_i2c_lookup(rdev, i2c_bus);
-				if (!radeon_connector->ddc_bus)
 					DRM_ERROR("DP: Failed to assign ddc bus! Check dmesg for i2c errors.\n");
 			}
 			drm_object_attach_property(&radeon_connector->base.base,
diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 063d4255137f..2f7cbb901fb1 100644
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -759,19 +759,18 @@ int radeon_ddc_get_modes(struct radeon_connector *radeon_connector)
 
 	if (radeon_connector_encoder_get_dp_bridge_encoder_id(&radeon_connector->base) !=
 	    ENCODER_OBJECT_ID_NONE) {
-		struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
-
-		if (dig->dp_i2c_bus)
+		if (radeon_connector->ddc_bus->has_aux)
 			radeon_connector->edid = drm_get_edid(&radeon_connector->base,
-							      &dig->dp_i2c_bus->adapter);
+							      &radeon_connector->ddc_bus->aux.ddc);
 	} else if ((radeon_connector->base.connector_type == DRM_MODE_CONNECTOR_DisplayPort) ||
 		   (radeon_connector->base.connector_type == DRM_MODE_CONNECTOR_eDP)) {
 		struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
 
 		if ((dig->dp_sink_type == CONNECTOR_OBJECT_ID_DISPLAYPORT ||
-		     dig->dp_sink_type == CONNECTOR_OBJECT_ID_eDP) && dig->dp_i2c_bus)
+		     dig->dp_sink_type == CONNECTOR_OBJECT_ID_eDP) &&
+		    radeon_connector->ddc_bus->has_aux)
 			radeon_connector->edid = drm_get_edid(&radeon_connector->base,
-							      &dig->dp_i2c_bus->adapter);
+							      &radeon_connector->ddc_bus->aux.ddc);
 		else if (radeon_connector->ddc_bus && !radeon_connector->edid)
 			radeon_connector->edid = drm_get_edid(&radeon_connector->base,
 							      &radeon_connector->ddc_bus->adapter);
diff --git a/drivers/gpu/drm/radeon/radeon_drv.c b/drivers/gpu/drm/radeon/radeon_drv.c
index 25127ba44ed9..c00a2f585185 100644
--- a/drivers/gpu/drm/radeon/radeon_drv.c
+++ b/drivers/gpu/drm/radeon/radeon_drv.c
@@ -185,7 +185,7 @@ module_param_named(dynclks, radeon_dynclks, int, 0444);
 MODULE_PARM_DESC(r4xx_atom, "Enable ATOMBIOS modesetting for R4xx");
 module_param_named(r4xx_atom, radeon_r4xx_atom, int, 0444);
 
-MODULE_PARM_DESC(vramlimit, "Restrict VRAM for testing");
+MODULE_PARM_DESC(vramlimit, "Restrict VRAM for testing, in megabytes");
 module_param_named(vramlimit, radeon_vram_limit, int, 0600);
 
 MODULE_PARM_DESC(agpmode, "AGP Mode (-1 == PCI)");
diff --git a/drivers/gpu/drm/radeon/radeon_i2c.c b/drivers/gpu/drm/radeon/radeon_i2c.c
index e24ca6ab96de..7b944142a9fd 100644
--- a/drivers/gpu/drm/radeon/radeon_i2c.c
+++ b/drivers/gpu/drm/radeon/radeon_i2c.c
@@ -64,8 +64,7 @@ bool radeon_ddc_probe(struct radeon_connector *radeon_connector, bool use_aux)
 		radeon_router_select_ddc_port(radeon_connector);
 
 	if (use_aux) {
-		struct radeon_connector_atom_dig *dig = radeon_connector->con_priv;
-		ret = i2c_transfer(&dig->dp_i2c_bus->adapter, msgs, 2);
+		ret = i2c_transfer(&radeon_connector->ddc_bus->aux.ddc, msgs, 2);
 	} else {
 		ret = i2c_transfer(&radeon_connector->ddc_bus->adapter, msgs, 2);
 	}
@@ -950,16 +949,16 @@ struct radeon_i2c_chan *radeon_i2c_create(struct drm_device *dev,
 		/* set the radeon bit adapter */
 		snprintf(i2c->adapter.name, sizeof(i2c->adapter.name),
 			 "Radeon i2c bit bus %s", name);
-		i2c->adapter.algo_data = &i2c->algo.bit;
-		i2c->algo.bit.pre_xfer = pre_xfer;
-		i2c->algo.bit.post_xfer = post_xfer;
-		i2c->algo.bit.setsda = set_data;
-		i2c->algo.bit.setscl = set_clock;
-		i2c->algo.bit.getsda = get_data;
-		i2c->algo.bit.getscl = get_clock;
-		i2c->algo.bit.udelay = 10;
-		i2c->algo.bit.timeout = usecs_to_jiffies(2200);	/* from VESA */
-		i2c->algo.bit.data = i2c;
+		i2c->adapter.algo_data = &i2c->bit;
+		i2c->bit.pre_xfer = pre_xfer;
+		i2c->bit.post_xfer = post_xfer;
+		i2c->bit.setsda = set_data;
+		i2c->bit.setscl = set_clock;
+		i2c->bit.getsda = get_data;
+		i2c->bit.getscl = get_clock;
+		i2c->bit.udelay = 10;
+		i2c->bit.timeout = usecs_to_jiffies(2200);	/* from VESA */
+		i2c->bit.data = i2c;
 		ret = i2c_bit_add_bus(&i2c->adapter);
 		if (ret) {
 			DRM_ERROR("Failed to register bit i2c %s\n", name);
@@ -974,46 +973,13 @@ out_free:
 
 }
 
-struct radeon_i2c_chan *radeon_i2c_create_dp(struct drm_device *dev,
-					     struct radeon_i2c_bus_rec *rec,
-					     const char *name)
-{
-	struct radeon_i2c_chan *i2c;
-	int ret;
-
-	i2c = kzalloc(sizeof(struct radeon_i2c_chan), GFP_KERNEL);
-	if (i2c == NULL)
-		return NULL;
-
-	i2c->rec = *rec;
-	i2c->adapter.owner = THIS_MODULE;
-	i2c->adapter.class = I2C_CLASS_DDC;
-	i2c->adapter.dev.parent = &dev->pdev->dev;
-	i2c->dev = dev;
-	snprintf(i2c->adapter.name, sizeof(i2c->adapter.name),
-		 "Radeon aux bus %s", name);
-	i2c_set_adapdata(&i2c->adapter, i2c);
-	i2c->adapter.algo_data = &i2c->algo.dp;
-	i2c->algo.dp.aux_ch = radeon_dp_i2c_aux_ch;
-	i2c->algo.dp.address = 0;
-	ret = i2c_dp_aux_add_bus(&i2c->adapter);
-	if (ret) {
-		DRM_INFO("Failed to register i2c %s\n", name);
-		goto out_free;
-	}
-
-	return i2c;
-out_free:
-	kfree(i2c);
-	return NULL;
-
-}
-
 void radeon_i2c_destroy(struct radeon_i2c_chan *i2c)
 {
 	if (!i2c)
 		return;
 	i2c_del_adapter(&i2c->adapter);
+	if (i2c->has_aux)
+		drm_dp_aux_unregister_i2c_bus(&i2c->aux);
 	kfree(i2c);
 }
 
diff --git a/drivers/gpu/drm/radeon/radeon_mode.h b/drivers/gpu/drm/radeon/radeon_mode.h
index 832d9fa1a4c4..6ddf31a2d34e 100644
--- a/drivers/gpu/drm/radeon/radeon_mode.h
+++ b/drivers/gpu/drm/radeon/radeon_mode.h
@@ -187,12 +187,10 @@ struct radeon_pll {
 struct radeon_i2c_chan {
 	struct i2c_adapter adapter;
 	struct drm_device *dev;
-	union {
-		struct i2c_algo_bit_data bit;
-		struct i2c_algo_dp_aux_data dp;
-	} algo;
+	struct i2c_algo_bit_data bit;
 	struct radeon_i2c_bus_rec rec;
 	struct drm_dp_aux aux;
+	bool has_aux;
 };
 
 /* mostly for macs, but really any system without connector tables */
@@ -440,7 +438,6 @@ struct radeon_encoder {
 struct radeon_connector_atom_dig {
 	uint32_t igp_lane_info;
 	/* displayport */
-	struct radeon_i2c_chan *dp_i2c_bus;
 	u8 dpcd[DP_RECEIVER_CAP_SIZE];
 	u8 dp_sink_type;
 	int dp_clock;
@@ -702,8 +699,6 @@ extern void atombios_dig_transmitter_setup(struct drm_encoder *encoder,
 					   uint8_t lane_set);
 extern void radeon_atom_ext_encoder_setup_ddc(struct drm_encoder *encoder);
 extern struct drm_encoder *radeon_get_external_encoder(struct drm_encoder *encoder);
-extern int radeon_dp_i2c_aux_ch(struct i2c_adapter *adapter, int mode,
-				u8 write_byte, u8 *read_byte);
 void radeon_atom_copy_swap(u8 *dst, u8 *src, u8 num_bytes, bool to_le);
 
 extern void radeon_i2c_init(struct radeon_device *rdev);
@@ -715,9 +710,6 @@ extern void radeon_i2c_add(struct radeon_device *rdev,
 			   const char *name);
 extern struct radeon_i2c_chan *radeon_i2c_lookup(struct radeon_device *rdev,
 						 struct radeon_i2c_bus_rec *i2c_bus);
-extern struct radeon_i2c_chan *radeon_i2c_create_dp(struct drm_device *dev,
-						    struct radeon_i2c_bus_rec *rec,
-						    const char *name);
 extern struct radeon_i2c_chan *radeon_i2c_create(struct drm_device *dev,
 						 struct radeon_i2c_bus_rec *rec,
 						 const char *name);
diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c
index d536ed381fbd..005c19bd92df 100644
--- a/drivers/gpu/drm/tegra/dpaux.c
+++ b/drivers/gpu/drm/tegra/dpaux.c
@@ -99,55 +99,73 @@ static void tegra_dpaux_read_fifo(struct tegra_dpaux *dpaux, u8 *buffer,
 static ssize_t tegra_dpaux_transfer(struct drm_dp_aux *aux,
 				    struct drm_dp_aux_msg *msg)
 {
-	unsigned long value = DPAUX_DP_AUXCTL_TRANSACTREQ;
 	unsigned long timeout = msecs_to_jiffies(250);
 	struct tegra_dpaux *dpaux = to_dpaux(aux);
 	unsigned long status;
 	ssize_t ret = 0;
+	u32 value;
 
-	if (msg->size < 1 || msg->size > 16)
+	/* Tegra has 4x4 byte DP AUX transmit and receive FIFOs. */
+	if (msg->size > 16)
 		return -EINVAL;
 
-	tegra_dpaux_writel(dpaux, msg->address, DPAUX_DP_AUXADDR);
+	/*
+	 * Allow zero-sized messages only for I2C, in which case they specify
+	 * address-only transactions.
+	 */
+	if (msg->size < 1) {
+		switch (msg->request & ~DP_AUX_I2C_MOT) {
+		case DP_AUX_I2C_WRITE:
+		case DP_AUX_I2C_READ:
+			value = DPAUX_DP_AUXCTL_CMD_ADDRESS_ONLY;
+			break;
+
+		default:
+			return -EINVAL;
+		}
+	} else {
+		/* For non-zero-sized messages, set the CMDLEN field. */
+		value = DPAUX_DP_AUXCTL_CMDLEN(msg->size - 1);
+	}
 
 	switch (msg->request & ~DP_AUX_I2C_MOT) {
 	case DP_AUX_I2C_WRITE:
 		if (msg->request & DP_AUX_I2C_MOT)
-			value = DPAUX_DP_AUXCTL_CMD_MOT_WR;
+			value |= DPAUX_DP_AUXCTL_CMD_MOT_WR;
 		else
-			value = DPAUX_DP_AUXCTL_CMD_I2C_WR;
+			value |= DPAUX_DP_AUXCTL_CMD_I2C_WR;
 
 		break;
 
 	case DP_AUX_I2C_READ:
 		if (msg->request & DP_AUX_I2C_MOT)
-			value = DPAUX_DP_AUXCTL_CMD_MOT_RD;
+			value |= DPAUX_DP_AUXCTL_CMD_MOT_RD;
 		else
-			value = DPAUX_DP_AUXCTL_CMD_I2C_RD;
+			value |= DPAUX_DP_AUXCTL_CMD_I2C_RD;
 
 		break;
 
 	case DP_AUX_I2C_STATUS:
 		if (msg->request & DP_AUX_I2C_MOT)
-			value = DPAUX_DP_AUXCTL_CMD_MOT_RQ;
+			value |= DPAUX_DP_AUXCTL_CMD_MOT_RQ;
 		else
-			value = DPAUX_DP_AUXCTL_CMD_I2C_RQ;
+			value |= DPAUX_DP_AUXCTL_CMD_I2C_RQ;
 
 		break;
 
 	case DP_AUX_NATIVE_WRITE:
-		value = DPAUX_DP_AUXCTL_CMD_AUX_WR;
+		value |= DPAUX_DP_AUXCTL_CMD_AUX_WR;
 		break;
 
 	case DP_AUX_NATIVE_READ:
-		value = DPAUX_DP_AUXCTL_CMD_AUX_RD;
+		value |= DPAUX_DP_AUXCTL_CMD_AUX_RD;
 		break;
 
 	default:
 		return -EINVAL;
 	}
 
-	value |= DPAUX_DP_AUXCTL_CMDLEN(msg->size - 1);
+	tegra_dpaux_writel(dpaux, msg->address, DPAUX_DP_AUXADDR);
 	tegra_dpaux_writel(dpaux, value, DPAUX_DP_AUXCTL);
 
 	if ((msg->request & DP_AUX_I2C_READ) == 0) {
@@ -198,7 +216,7 @@ static ssize_t tegra_dpaux_transfer(struct drm_dp_aux *aux,
 		break;
 	}
 
-	if (msg->reply == DP_AUX_NATIVE_REPLY_ACK) {
+	if ((msg->size > 0) && (msg->reply == DP_AUX_NATIVE_REPLY_ACK)) {
 		if (msg->request & DP_AUX_I2C_READ) {
 			size_t count = value & DPAUX_DP_AUXSTAT_REPLY_MASK;
 
diff --git a/drivers/gpu/drm/tegra/dpaux.h b/drivers/gpu/drm/tegra/dpaux.h
index 4f5bf10fdff9..806e245ca787 100644
--- a/drivers/gpu/drm/tegra/dpaux.h
+++ b/drivers/gpu/drm/tegra/dpaux.h
@@ -32,6 +32,7 @@
 #define DPAUX_DP_AUXCTL_CMD_I2C_RQ (2 << 12)
 #define DPAUX_DP_AUXCTL_CMD_I2C_RD (1 << 12)
 #define DPAUX_DP_AUXCTL_CMD_I2C_WR (0 << 12)
+#define DPAUX_DP_AUXCTL_CMD_ADDRESS_ONLY (1 << 8)
 #define DPAUX_DP_AUXCTL_CMDLEN(x) ((x) & 0xff)
 
 #define DPAUX_DP_AUXSTAT 0x31
diff --git a/include/drm/drm_dp_helper.h b/include/drm/drm_dp_helper.h
index b4f58914bf7d..cfcacec5b89d 100644
--- a/include/drm/drm_dp_helper.h
+++ b/include/drm/drm_dp_helper.h
@@ -456,6 +456,10 @@ struct drm_dp_aux_msg {
  * transactions. The drm_dp_aux_register_i2c_bus() function registers an
  * I2C adapter that can be passed to drm_probe_ddc(). Upon removal, drivers
  * should call drm_dp_aux_unregister_i2c_bus() to remove the I2C adapter.
+ *
+ * Note that the aux helper code assumes that the .transfer() function
+ * only modifies the reply field of the drm_dp_aux_msg structure.  The
+ * retry logic and i2c helpers assume this is the case.
  */
 struct drm_dp_aux {
 	const char *name;