WebSVN – Kolibri OS – Diff – /drivers/video/drm/drm_dp_helper.c

 /*
  * Copyright © 2009 Keith Packard
+ *
  * Permission to use, copy, modify, distribute, and sell this software and its
  * documentation for any purpose is hereby granted without fee, provided that
  * the above copyright notice appear in all copies and that both that copyright
  * notice and this permission notice appear in supporting documentation, and
  * that the name of the copyright holders not be used in advertising or
  * publicity pertaining to distribution of the software without specific,
  * written prior permission.  The copyright holders make no representations
  * about the suitability of this software for any purpose.  It is provided "as
  * is" without express or implied warranty.
+ *
  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
  * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
  * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
  * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  * OF THIS SOFTWARE.
  */
 #include
 #include
 //#include
 //#include
 #include
 #include
 #include
-#include
 #include
+#include
 /**
  * DOC: dp helpers
+ *
  * These functions contain some common logic and helpers at various abstraction
  * levels to deal with Display Port sink devices and related things like DP aux
  * channel transfers, EDID reading over DP aux channels, decoding certain DPCD
  * blocks, ...
  */
-/* Run a single AUX_CH I2C transaction, writing/reading data as necessary */
-static int
-i2c_algo_dp_aux_transaction(struct i2c_adapter *adapter, int mode,
-			    uint8_t write_byte, uint8_t *read_byte)
-{
-	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
-	int ret;
-	ret = (*algo_data->aux_ch)(adapter, mode,
-				   write_byte, read_byte);
-	return ret;
-}
-/*
- * I2C over AUX CH
- */
-/*
- * Send the address. If the I2C link is running, this 'restarts'
- * the connection with the new address, this is used for doing
- * a write followed by a read (as needed for DDC)
- */
-static int
-i2c_algo_dp_aux_address(struct i2c_adapter *adapter, u16 address, bool reading)
-{
-	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
-	int mode = MODE_I2C_START;
-	int ret;
-	if (reading)
-		mode |= MODE_I2C_READ;
-	else
-		mode |= MODE_I2C_WRITE;
-	algo_data->address = address;
-	algo_data->running = true;
-	ret = i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
-	return ret;
-}
-/*
- * Stop the I2C transaction. This closes out the link, sending
- * a bare address packet with the MOT bit turned off
- */
-static void
-i2c_algo_dp_aux_stop(struct i2c_adapter *adapter, bool reading)
-{
-	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
-	int mode = MODE_I2C_STOP;
-	if (reading)
-		mode |= MODE_I2C_READ;
-	else
-		mode |= MODE_I2C_WRITE;
-	if (algo_data->running) {
-		(void) i2c_algo_dp_aux_transaction(adapter, mode, 0, NULL);
-		algo_data->running = false;
-	}
-}
-/*
- * Write a single byte to the current I2C address, the
- * the I2C link must be running or this returns -EIO
- */
-static int
-i2c_algo_dp_aux_put_byte(struct i2c_adapter *adapter, u8 byte)
-{
-	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
-	int ret;
-	if (!algo_data->running)
-		return -EIO;
-	ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_WRITE, byte, NULL);
-	return ret;
-}
-/*
- * Read a single byte from the current I2C address, the
- * I2C link must be running or this returns -EIO
- */
-static int
-i2c_algo_dp_aux_get_byte(struct i2c_adapter *adapter, u8 *byte_ret)
-{
-	struct i2c_algo_dp_aux_data *algo_data = adapter->algo_data;
-	int ret;
-	if (!algo_data->running)
-		return -EIO;
-	ret = i2c_algo_dp_aux_transaction(adapter, MODE_I2C_READ, 0, byte_ret);
-	return ret;
-}
-static int
-i2c_algo_dp_aux_xfer(struct i2c_adapter *adapter,
-		     struct i2c_msg *msgs,
-		     int num)
-{
-	int ret = 0;
-	bool reading = false;
-	int m;
-	int b;
-	for (m = 0; m < num; m++) {
-		u16 len = msgs[m].len;
-		u8 *buf = msgs[m].buf;
-		reading = (msgs[m].flags & I2C_M_RD) != 0;
-		ret = i2c_algo_dp_aux_address(adapter, msgs[m].addr, reading);
-		if (ret < 0)
-			break;
-		if (reading) {
-			for (b = 0; b < len; b++) {
-				ret = i2c_algo_dp_aux_get_byte(adapter, &buf[b]);
-				if (ret < 0)
-					break;
-			}
-		} else {
-			for (b = 0; b < len; b++) {
-				ret = i2c_algo_dp_aux_put_byte(adapter, buf[b]);
-				if (ret < 0)
-					break;
-			}
-		}
-		if (ret < 0)
-			break;
-	}
-	if (ret >= 0)
-		ret = num;
-	i2c_algo_dp_aux_stop(adapter, reading);
-	DRM_DEBUG_KMS("dp_aux_xfer return %d\n", ret);
-	return ret;
-}
-static u32
-i2c_algo_dp_aux_functionality(struct i2c_adapter *adapter)
-{
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
-	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
-	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
-	       I2C_FUNC_10BIT_ADDR;
-}
-static const struct i2c_algorithm i2c_dp_aux_algo = {
-	.master_xfer	= i2c_algo_dp_aux_xfer,
-	.functionality	= i2c_algo_dp_aux_functionality,
-};
-static void
-i2c_dp_aux_reset_bus(struct i2c_adapter *adapter)
-{
-	(void) i2c_algo_dp_aux_address(adapter, 0, false);
-	(void) i2c_algo_dp_aux_stop(adapter, false);
-}
-static int
-i2c_dp_aux_prepare_bus(struct i2c_adapter *adapter)
-{
-	adapter->algo = &i2c_dp_aux_algo;
-	adapter->retries = 3;
-	i2c_dp_aux_reset_bus(adapter);
-	return 0;
-}
-/**
- * i2c_dp_aux_add_bus() - register an i2c adapter using the aux ch helper
- * @adapter: i2c adapter to register
- *
- * This registers an i2c adapter that uses dp aux channel as it's underlaying
- * transport. The driver needs to fill out the &i2c_algo_dp_aux_data structure
- * and store it in the algo_data member of the @adapter argument. This will be
- * used by the i2c over dp aux algorithm to drive the hardware.
- *
- * RETURNS:
- * 0 on success, -ERRNO on failure.
- *
- * IMPORTANT:
- * This interface is deprecated, please switch to the new dp aux helpers and
- * drm_dp_aux_register().
- */
-int
-i2c_dp_aux_add_bus(struct i2c_adapter *adapter)
-{
-	int error;
-	error = i2c_dp_aux_prepare_bus(adapter);
-	if (error)
-		return error;
-	error = i2c_add_adapter(adapter);
-	return error;
-}
-EXPORT_SYMBOL(i2c_dp_aux_add_bus);
 /* Helpers for DP link training */
 static u8 dp_link_status(const u8 link_status[DP_LINK_STATUS_SIZE], int r)
+{
 	return link_status[r - DP_LANE0_1_STATUS];
+}
 static u8 dp_get_lane_status(const u8 link_status[DP_LINK_STATUS_SIZE],
 			     int lane)
+{
 	int i = DP_LANE0_1_STATUS + (lane >> 1);
 	int s = (lane & 1) * 4;
 	u8 l = dp_link_status(link_status, i);
 	return (l >> s) & 0xf;
+}
 bool drm_dp_channel_eq_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
 			  int lane_count)
+{
 	u8 lane_align;
 	u8 lane_status;
 	int lane;
 	lane_align = dp_link_status(link_status,
 				    DP_LANE_ALIGN_STATUS_UPDATED);
 	if ((lane_align & DP_INTERLANE_ALIGN_DONE) == 0)
 		return false;
 	for (lane = 0; lane < lane_count; lane++) {
 		lane_status = dp_get_lane_status(link_status, lane);
 		if ((lane_status & DP_CHANNEL_EQ_BITS) != DP_CHANNEL_EQ_BITS)
 			return false;
+	}
 	return true;
+}
 EXPORT_SYMBOL(drm_dp_channel_eq_ok);
 bool drm_dp_clock_recovery_ok(const u8 link_status[DP_LINK_STATUS_SIZE],
 			      int lane_count)
+{
 	int lane;
 	u8 lane_status;
 	for (lane = 0; lane < lane_count; lane++) {
 		lane_status = dp_get_lane_status(link_status, lane);
 		if ((lane_status & DP_LANE_CR_DONE) == 0)
 			return false;
+	}
 	return true;
+}
 EXPORT_SYMBOL(drm_dp_clock_recovery_ok);
 u8 drm_dp_get_adjust_request_voltage(const u8 link_status[DP_LINK_STATUS_SIZE],
 				     int lane)
+{
 	int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
 	int s = ((lane & 1) ?
 		 DP_ADJUST_VOLTAGE_SWING_LANE1_SHIFT :
 		 DP_ADJUST_VOLTAGE_SWING_LANE0_SHIFT);
 	u8 l = dp_link_status(link_status, i);
 	return ((l >> s) & 0x3) << DP_TRAIN_VOLTAGE_SWING_SHIFT;
+}
 EXPORT_SYMBOL(drm_dp_get_adjust_request_voltage);
 u8 drm_dp_get_adjust_request_pre_emphasis(const u8 link_status[DP_LINK_STATUS_SIZE],
 					  int lane)
+{
 	int i = DP_ADJUST_REQUEST_LANE0_1 + (lane >> 1);
 	int s = ((lane & 1) ?
 		 DP_ADJUST_PRE_EMPHASIS_LANE1_SHIFT :
 		 DP_ADJUST_PRE_EMPHASIS_LANE0_SHIFT);
 	u8 l = dp_link_status(link_status, i);
 	return ((l >> s) & 0x3) << DP_TRAIN_PRE_EMPHASIS_SHIFT;
+}
 EXPORT_SYMBOL(drm_dp_get_adjust_request_pre_emphasis);
 void drm_dp_link_train_clock_recovery_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
 	if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0)
 		udelay(100);
 	else
 		mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4);
+}
 EXPORT_SYMBOL(drm_dp_link_train_clock_recovery_delay);
 void drm_dp_link_train_channel_eq_delay(const u8 dpcd[DP_RECEIVER_CAP_SIZE]) {
 	if (dpcd[DP_TRAINING_AUX_RD_INTERVAL] == 0)
 		udelay(400);
 	else
 		mdelay(dpcd[DP_TRAINING_AUX_RD_INTERVAL] * 4);
+}
 EXPORT_SYMBOL(drm_dp_link_train_channel_eq_delay);
 u8 drm_dp_link_rate_to_bw_code(int link_rate)
+{
 	switch (link_rate) {
 	case 162000:
 	default:
 		return DP_LINK_BW_1_62;
 	case 270000:
 		return DP_LINK_BW_2_7;
 	case 540000:
 		return DP_LINK_BW_5_4;
+	}
+}
 EXPORT_SYMBOL(drm_dp_link_rate_to_bw_code);
 int drm_dp_bw_code_to_link_rate(u8 link_bw)
+{
 	switch (link_bw) {
 	case DP_LINK_BW_1_62:
 	default:
 		return 162000;
 	case DP_LINK_BW_2_7:
 		return 270000;
 	case DP_LINK_BW_5_4:
 		return 540000;
+	}
+}
 EXPORT_SYMBOL(drm_dp_bw_code_to_link_rate);
 /**
  * DOC: dp helpers
+ *
  * The DisplayPort AUX channel is an abstraction to allow generic, driver-
  * independent access to AUX functionality. Drivers can take advantage of
  * this by filling in the fields of the drm_dp_aux structure.
+ *
  * Transactions are described using a hardware-independent drm_dp_aux_msg
  * structure, which is passed into a driver's .transfer() implementation.
  * Both native and I2C-over-AUX transactions are supported.
  */
 static int drm_dp_dpcd_access(struct drm_dp_aux *aux, u8 request,
 			      unsigned int offset, void *buffer, size_t size)
+{
 	struct drm_dp_aux_msg msg;
 	unsigned int retry;
 	int err;
 	memset(&msg, 0, sizeof(msg));
 	msg.address = offset;
 	msg.request = request;
 	msg.buffer = buffer;
 	msg.size = size;
 	/*
 	 * The specification doesn't give any recommendation on how often to
-	 * retry native transactions, so retry 7 times like for I2C-over-AUX
+	 * retry native transactions. We used to retry 7 times like for
-	 * transactions.
+	 * aux i2c transactions but real world devices this wasn't
+	 * sufficient, bump to 32 which makes Dell 4k monitors happier.
 	 */
-	for (retry = 0; retry < 7; retry++) {
+	for (retry = 0; retry < 32; retry++) {
 		mutex_lock(&aux->hw_mutex);
 		err = aux->transfer(aux, &msg);
 		mutex_unlock(&aux->hw_mutex);
 		if (err < 0) {
 			if (err == -EBUSY)
 				continue;
 			return err;
+		}
 		switch (msg.reply & DP_AUX_NATIVE_REPLY_MASK) {
 		case DP_AUX_NATIVE_REPLY_ACK:
 			if (err < size)
 				return -EPROTO;
 			return err;
 		case DP_AUX_NATIVE_REPLY_NACK:
 			return -EIO;
 		case DP_AUX_NATIVE_REPLY_DEFER:
 			usleep(500);
 			break;
+		}
+	}
 	DRM_DEBUG_KMS("too many retries, giving up\n");
 	return -EIO;
+}
 /**
  * drm_dp_dpcd_read() - read a series of bytes from the DPCD
  * @aux: DisplayPort AUX channel
  * @offset: address of the (first) register to read
  * @buffer: buffer to store the register values
  * @size: number of bytes in @buffer
+ *
  * Returns the number of bytes transferred on success, or a negative error
  * code on failure. -EIO is returned if the request was NAKed by the sink or
  * if the retry count was exceeded. If not all bytes were transferred, this
  * function returns -EPROTO. Errors from the underlying AUX channel transfer
  * function, with the exception of -EBUSY (which causes the transaction to
  * be retried), are propagated to the caller.
  */
 ssize_t drm_dp_dpcd_read(struct drm_dp_aux *aux, unsigned int offset,
 			 void *buffer, size_t size)
+{
 	return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_READ, offset, buffer,
 				  size);
+}
 EXPORT_SYMBOL(drm_dp_dpcd_read);
 /**
  * drm_dp_dpcd_write() - write a series of bytes to the DPCD
  * @aux: DisplayPort AUX channel
  * @offset: address of the (first) register to write
  * @buffer: buffer containing the values to write
  * @size: number of bytes in @buffer
+ *
  * Returns the number of bytes transferred on success, or a negative error
  * code on failure. -EIO is returned if the request was NAKed by the sink or
  * if the retry count was exceeded. If not all bytes were transferred, this
  * function returns -EPROTO. Errors from the underlying AUX channel transfer
  * function, with the exception of -EBUSY (which causes the transaction to
  * be retried), are propagated to the caller.
  */
 ssize_t drm_dp_dpcd_write(struct drm_dp_aux *aux, unsigned int offset,
 			  void *buffer, size_t size)
+{
 	return drm_dp_dpcd_access(aux, DP_AUX_NATIVE_WRITE, offset, buffer,
 				  size);
+}
 EXPORT_SYMBOL(drm_dp_dpcd_write);
 /**
  * drm_dp_dpcd_read_link_status() - read DPCD link status (bytes 0x202-0x207)
  * @aux: DisplayPort AUX channel
  * @status: buffer to store the link status in (must be at least 6 bytes)
+ *
  * Returns the number of bytes transferred on success or a negative error
  * code on failure.
  */
 int drm_dp_dpcd_read_link_status(struct drm_dp_aux *aux,
 				 u8 status[DP_LINK_STATUS_SIZE])
+{
 	return drm_dp_dpcd_read(aux, DP_LANE0_1_STATUS, status,
 				DP_LINK_STATUS_SIZE);
+}
 EXPORT_SYMBOL(drm_dp_dpcd_read_link_status);
 /**
  * drm_dp_link_probe() - probe a DisplayPort link for capabilities
  * @aux: DisplayPort AUX channel
  * @link: pointer to structure in which to return link capabilities
+ *
  * The structure filled in by this function can usually be passed directly
  * into drm_dp_link_power_up() and drm_dp_link_configure() to power up and
  * configure the link based on the link's capabilities.
+ *
  * Returns 0 on success or a negative error code on failure.
  */
 int drm_dp_link_probe(struct drm_dp_aux *aux, struct drm_dp_link *link)
+{
 	u8 values[3];
 	int err;
 	memset(link, 0, sizeof(*link));
 	err = drm_dp_dpcd_read(aux, DP_DPCD_REV, values, sizeof(values));
 	if (err < 0)
 		return err;
 	link->revision = values[0];
 	link->rate = drm_dp_bw_code_to_link_rate(values[1]);
 	link->num_lanes = values[2] & DP_MAX_LANE_COUNT_MASK;
 	if (values[2] & DP_ENHANCED_FRAME_CAP)
 		link->capabilities |= DP_LINK_CAP_ENHANCED_FRAMING;
 	return 0;
+}
 EXPORT_SYMBOL(drm_dp_link_probe);
 /**
  * drm_dp_link_power_up() - power up a DisplayPort link
  * @aux: DisplayPort AUX channel
  * @link: pointer to a structure containing the link configuration
+ *
  * Returns 0 on success or a negative error code on failure.
  */
 int drm_dp_link_power_up(struct drm_dp_aux *aux, struct drm_dp_link *link)
+{
 	u8 value;
 	int err;
 	/* DP_SET_POWER register is only available on DPCD v1.1 and later */
 	if (link->revision < 0x11)
 		return 0;
 	err = drm_dp_dpcd_readb(aux, DP_SET_POWER, &value);
 	if (err < 0)
 		return err;
 	value &= ~DP_SET_POWER_MASK;
 	value |= DP_SET_POWER_D0;
 	err = drm_dp_dpcd_writeb(aux, DP_SET_POWER, value);
 	if (err < 0)
 		return err;
 	/*
 	 * According to the DP 1.1 specification, a "Sink Device must exit the
 	 * power saving state within 1 ms" (Section 2.5.3.1, Table 5-52, "Sink
 	 * Control Field" (register 0x600).
 	 */
 	usleep(2000);
 	return 0;
+}
 EXPORT_SYMBOL(drm_dp_link_power_up);
 /**
  * drm_dp_link_configure() - configure a DisplayPort link
  * @aux: DisplayPort AUX channel
  * @link: pointer to a structure containing the link configuration
+ *
  * Returns 0 on success or a negative error code on failure.
  */
 int drm_dp_link_configure(struct drm_dp_aux *aux, struct drm_dp_link *link)
+{
 	u8 values[2];
 	int err;
 	values[0] = drm_dp_link_rate_to_bw_code(link->rate);
 	values[1] = link->num_lanes;
 	if (link->capabilities & DP_LINK_CAP_ENHANCED_FRAMING)
 		values[1] |= DP_LANE_COUNT_ENHANCED_FRAME_EN;
 	err = drm_dp_dpcd_write(aux, DP_LINK_BW_SET, values, sizeof(values));
 	if (err < 0)
 		return err;
 	return 0;
+}
 EXPORT_SYMBOL(drm_dp_link_configure);
 /*
  * I2C-over-AUX implementation
  */
 static u32 drm_dp_i2c_functionality(struct i2c_adapter *adapter)
+{
 	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
 	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
 	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
 	       I2C_FUNC_10BIT_ADDR;
+}
 /*
  * Transfer a single I2C-over-AUX message and handle various error conditions,
  * 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)
+{
 	unsigned int retry;
 	int err;
 	/*
 	 * DP1.2 sections 2.7.7.1.5.6.1 and 2.7.7.1.6.6.1: A DP Source device
 	 * is required to retry at least seven times upon receiving AUX_DEFER
 	 * before giving up the AUX transaction.
 	 */
 	for (retry = 0; retry < 7; retry++) {
 		mutex_lock(&aux->hw_mutex);
 		err = aux->transfer(aux, msg);
 		mutex_unlock(&aux->hw_mutex);
 		if (err < 0) {
 			if (err == -EBUSY)
 				continue;
 			DRM_DEBUG_KMS("transaction failed: %d\n", err);
 			return err;
+		}
 		switch (msg->reply & DP_AUX_NATIVE_REPLY_MASK) {
 		case DP_AUX_NATIVE_REPLY_ACK:
 			/*
 			 * For I2C-over-AUX transactions this isn't enough, we
 			 * need to check for the I2C ACK reply.
 			 */
 			break;
 		case DP_AUX_NATIVE_REPLY_NACK:
 			DRM_DEBUG_KMS("native nack\n");
 			return -EREMOTEIO;
 		case DP_AUX_NATIVE_REPLY_DEFER:
 			DRM_DEBUG_KMS("native defer");
 			/*
 			 * We could check for I2C bit rate capabilities and if
 			 * available adjust this interval. We could also be
 			 * more careful with DP-to-legacy adapters where a
 			 * long legacy cable may force very low I2C bit rates.
+			 *
 			 * For now just defer for long enough to hopefully be
 			 * safe for all use-cases.
 			 */
 			usleep_range(500, 600);
 			continue;
 		default:
 			DRM_ERROR("invalid native reply %#04x\n", msg->reply);
 			return -EREMOTEIO;
+		}
 		switch (msg->reply & DP_AUX_I2C_REPLY_MASK) {
 		case DP_AUX_I2C_REPLY_ACK:
 			/*
 			 * Both native ACK and I2C ACK replies received. We
 			 * can assume the transfer was successful.
 			 */
 			if (err < msg->size)
 				return -EPROTO;
 			return 0;
 		case DP_AUX_I2C_REPLY_NACK:
 			DRM_DEBUG_KMS("I2C nack\n");
 			return -EREMOTEIO;
 		case DP_AUX_I2C_REPLY_DEFER:
 			DRM_DEBUG_KMS("I2C defer\n");
 			usleep_range(400, 500);
 			continue;
 		default:
 			DRM_ERROR("invalid I2C reply %#04x\n", msg->reply);
 			return -EREMOTEIO;
+		}
+	}
 	DRM_DEBUG_KMS("too many retries, giving up\n");
 	return -EREMOTEIO;
+}
 static int drm_dp_i2c_xfer(struct i2c_adapter *adapter, struct i2c_msg *msgs,
 			   int num)
+{
 	struct drm_dp_aux *aux = adapter->algo_data;
 	unsigned int i, j;
 	struct drm_dp_aux_msg msg;
 	int err = 0;
 	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
 		 * transferring data in larger chunks can actually lead to
 		 * decreased performance. Therefore each message is simply
 		 * transferred byte-by-byte.
 		 */
 		for (j = 0; j < msgs[i].len; j++) {
 			msg.buffer = msgs[i].buf + j;
 			msg.size = 1;
 			err = drm_dp_i2c_do_msg(aux, &msg);
 			if (err < 0)
 				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 err;
+}
 static const struct i2c_algorithm drm_dp_i2c_algo = {
 	.functionality = drm_dp_i2c_functionality,
 	.master_xfer = drm_dp_i2c_xfer,
 };
 /**
  * drm_dp_aux_register() - initialise and register aux channel
  * @aux: DisplayPort AUX channel
+ *
  * Returns 0 on success or a negative error code on failure.
  */
 int drm_dp_aux_register(struct drm_dp_aux *aux)
+{
 	mutex_init(&aux->hw_mutex);
 	aux->ddc.algo = &drm_dp_i2c_algo;
 	aux->ddc.algo_data = aux;
 	aux->ddc.retries = 3;
 	aux->ddc.class = I2C_CLASS_DDC;
 	aux->ddc.owner = THIS_MODULE;
 	aux->ddc.dev.parent = aux->dev;
 //	aux->ddc.dev.of_node = aux->dev->of_node;
     strlcpy(aux->ddc.name, aux->name ? aux->name : "aux",
 		sizeof(aux->ddc.name));
 	return i2c_add_adapter(&aux->ddc);
+}
 EXPORT_SYMBOL(drm_dp_aux_register);
 /**
  * drm_dp_aux_unregister() - unregister an AUX adapter
  * @aux: DisplayPort AUX channel
  */
 void drm_dp_aux_unregister(struct drm_dp_aux *aux)
+{
 	i2c_del_adapter(&aux->ddc);
+}
 EXPORT_SYMBOL(drm_dp_aux_unregister);

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(root)/drivers/video/drm/drm_dp_helper.c – Rev 5060 → 5271