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video: exynos_dp: adjust voltage swing and pre-emphasis during Link Training

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This patch adds adjustement for voltage swing and pre-emphasis during
Link Training procedure. According to the DP specification, unless all
the LANEx_CR_DONE bits are set, the transmitter must read
the ADJUST_REQUEST_LANEx_x, increase the voltage swing according to
the request, and update the TRAINING_LANEx_SET bytes to match the new
voltage swing setting.

Refer to the DP specification v1.1a, Section 3.5.1.3 Link Training.

Signed-off-by: Jingoo Han <jg1.han@samsung.com>
Signed-off-by: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
This commit is contained in:
Jingoo Han 2012-07-19 13:52:59 +09:00 committed by Florian Tobias Schandinat
parent c1c52848ce
commit d5c0eed01c
2 changed files with 153 additions and 149 deletions
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300
drivers/video/exynos/exynos_dp_core.c
View file

@ -260,7 +260,7 @@ static void exynos_dp_set_lane_lane_pre_emphasis(struct exynos_dp_device *dp,
static void exynos_dp_link_start(struct exynos_dp_device *dp)
{
u8 buf[5];
u8 buf[4];
int lane;
int lane_count;
@ -295,10 +295,10 @@ static void exynos_dp_link_start(struct exynos_dp_device *dp)
exynos_dp_set_training_pattern(dp, TRAINING_PTN1);
/* Set RX training pattern */
buf[0] = DPCD_SCRAMBLING_DISABLED |
DPCD_TRAINING_PATTERN_1;
exynos_dp_write_byte_to_dpcd(dp,
DPCD_ADDR_TRAINING_PATTERN_SET, buf[0]);
DPCD_ADDR_TRAINING_PATTERN_SET,
DPCD_SCRAMBLING_DISABLED |
DPCD_TRAINING_PATTERN_1);
for (lane = 0; lane < lane_count; lane++)
buf[lane] = DPCD_PRE_EMPHASIS_PATTERN2_LEVEL0 |
@ -308,7 +308,7 @@ static void exynos_dp_link_start(struct exynos_dp_device *dp)
lane_count, buf);
}
static unsigned char exynos_dp_get_lane_status(u8 link_status[6], int lane)
static unsigned char exynos_dp_get_lane_status(u8 link_status[2], int lane)
{
int shift = (lane & 1) * 4;
u8 link_value = link_status[lane>>1];
@ -316,7 +316,7 @@ static unsigned char exynos_dp_get_lane_status(u8 link_status[6], int lane)
return (link_value >> shift) & 0xf;
}
static int exynos_dp_clock_recovery_ok(u8 link_status[6], int lane_count)
static int exynos_dp_clock_recovery_ok(u8 link_status[2], int lane_count)
{
int lane;
u8 lane_status;
@ -329,22 +329,23 @@ static int exynos_dp_clock_recovery_ok(u8 link_status[6], int lane_count)
return 0;
}
static int exynos_dp_channel_eq_ok(u8 link_status[6], int lane_count)
static int exynos_dp_channel_eq_ok(u8 link_align[3], int lane_count)
{
int lane;
u8 lane_align;
u8 lane_status;
lane_align = link_status[2];
lane_align = link_align[2];
if ((lane_align & DPCD_INTERLANE_ALIGN_DONE) == 0)
return -EINVAL;
for (lane = 0; lane < lane_count; lane++) {
lane_status = exynos_dp_get_lane_status(link_status, lane);
lane_status = exynos_dp_get_lane_status(link_align, lane);
lane_status &= DPCD_CHANNEL_EQ_BITS;
if (lane_status != DPCD_CHANNEL_EQ_BITS)
return -EINVAL;
}
return 0;
}
@ -417,69 +418,17 @@ static unsigned int exynos_dp_get_lane_link_training(
static void exynos_dp_reduce_link_rate(struct exynos_dp_device *dp)
{
if (dp->link_train.link_rate == LINK_RATE_2_70GBPS) {
/* set to reduced bit rate */
dp->link_train.link_rate = LINK_RATE_1_62GBPS;
dev_err(dp->dev, "set to bandwidth %.2x\n",
dp->link_train.link_rate);
dp->link_train.lt_state = START;
} else {
exynos_dp_training_pattern_dis(dp);
/* set enhanced mode if available */
exynos_dp_set_enhanced_mode(dp);
dp->link_train.lt_state = FAILED;
}
}
exynos_dp_training_pattern_dis(dp);
exynos_dp_set_enhanced_mode(dp);
static void exynos_dp_get_adjust_train(struct exynos_dp_device *dp,
u8 adjust_request[2])
{
int lane;
int lane_count;
u8 voltage_swing;
u8 pre_emphasis;
u8 training_lane;
lane_count = dp->link_train.lane_count;
for (lane = 0; lane < lane_count; lane++) {
voltage_swing = exynos_dp_get_adjust_request_voltage(
adjust_request, lane);
pre_emphasis = exynos_dp_get_adjust_request_pre_emphasis(
adjust_request, lane);
training_lane = DPCD_VOLTAGE_SWING_SET(voltage_swing) |
DPCD_PRE_EMPHASIS_SET(pre_emphasis);
if (voltage_swing == VOLTAGE_LEVEL_3 ||
pre_emphasis == PRE_EMPHASIS_LEVEL_3) {
training_lane |= DPCD_MAX_SWING_REACHED;
training_lane |= DPCD_MAX_PRE_EMPHASIS_REACHED;
}
dp->link_train.training_lane[lane] = training_lane;
}
}
static int exynos_dp_check_max_cr_loop(struct exynos_dp_device *dp,
u8 voltage_swing)
{
int lane;
int lane_count;
lane_count = dp->link_train.lane_count;
for (lane = 0; lane < lane_count; lane++) {
if (voltage_swing == VOLTAGE_LEVEL_3 ||
dp->link_train.cr_loop[lane] == MAX_CR_LOOP)
return -EINVAL;
}
return 0;
dp->link_train.lt_state = FAILED;
}
static int exynos_dp_process_clock_recovery(struct exynos_dp_device *dp)
{
u8 data;
u8 link_status[6];
u8 link_status[2];
int lane;
int lane_count;
u8 buf[5];
u8 adjust_request[2];
u8 voltage_swing;
@ -488,98 +437,152 @@ static int exynos_dp_process_clock_recovery(struct exynos_dp_device *dp)
usleep_range(100, 101);
exynos_dp_read_bytes_from_dpcd(dp, DPCD_ADDR_LANE0_1_STATUS,
6, link_status);
lane_count = dp->link_train.lane_count;
exynos_dp_read_bytes_from_dpcd(dp, DPCD_ADDR_LANE0_1_STATUS,
2, link_status);
if (exynos_dp_clock_recovery_ok(link_status, lane_count) == 0) {
/* set training pattern 2 for EQ */
exynos_dp_set_training_pattern(dp, TRAINING_PTN2);
adjust_request[0] = link_status[4];
adjust_request[1] = link_status[5];
exynos_dp_get_adjust_train(dp, adjust_request);
buf[0] = DPCD_SCRAMBLING_DISABLED |
DPCD_TRAINING_PATTERN_2;
exynos_dp_write_byte_to_dpcd(dp,
DPCD_ADDR_TRAINING_PATTERN_SET,
buf[0]);
for (lane = 0; lane < lane_count; lane++) {
exynos_dp_set_lane_link_training(dp,
dp->link_train.training_lane[lane],
lane);
buf[lane] = dp->link_train.training_lane[lane];
exynos_dp_write_byte_to_dpcd(dp,
DPCD_ADDR_TRAINING_LANE0_SET + lane,
buf[lane]);
}
dp->link_train.lt_state = EQUALIZER_TRAINING;
} else {
exynos_dp_read_byte_from_dpcd(dp,
DPCD_ADDR_ADJUST_REQUEST_LANE0_1,
&data);
adjust_request[0] = data;
exynos_dp_read_byte_from_dpcd(dp,
DPCD_ADDR_ADJUST_REQUEST_LANE2_3,
&data);
adjust_request[1] = data;
for (lane = 0; lane < lane_count; lane++) {
training_lane = exynos_dp_get_lane_link_training(
dp, lane);
exynos_dp_read_bytes_from_dpcd(dp,
DPCD_ADDR_ADJUST_REQUEST_LANE0_1,
2, adjust_request);
voltage_swing = exynos_dp_get_adjust_request_voltage(
adjust_request, lane);
pre_emphasis = exynos_dp_get_adjust_request_pre_emphasis(
adjust_request, lane);
if ((DPCD_VOLTAGE_SWING_GET(training_lane) == voltage_swing) &&
(DPCD_PRE_EMPHASIS_GET(training_lane) == pre_emphasis))
dp->link_train.cr_loop[lane]++;
training_lane = DPCD_VOLTAGE_SWING_SET(voltage_swing) |
DPCD_PRE_EMPHASIS_SET(pre_emphasis);
if (voltage_swing == VOLTAGE_LEVEL_3)
training_lane |= DPCD_MAX_SWING_REACHED;
if (pre_emphasis == PRE_EMPHASIS_LEVEL_3)
training_lane |= DPCD_MAX_PRE_EMPHASIS_REACHED;
dp->link_train.training_lane[lane] = training_lane;
exynos_dp_set_lane_link_training(dp,
dp->link_train.training_lane[lane],
lane);
}
if (exynos_dp_check_max_cr_loop(dp, voltage_swing) != 0) {
exynos_dp_reduce_link_rate(dp);
} else {
exynos_dp_get_adjust_train(dp, adjust_request);
exynos_dp_write_byte_to_dpcd(dp,
DPCD_ADDR_TRAINING_PATTERN_SET,
DPCD_SCRAMBLING_DISABLED |
DPCD_TRAINING_PATTERN_2);
for (lane = 0; lane < lane_count; lane++) {
exynos_dp_set_lane_link_training(dp,
dp->link_train.training_lane[lane],
lane);
buf[lane] = dp->link_train.training_lane[lane];
exynos_dp_write_byte_to_dpcd(dp,
DPCD_ADDR_TRAINING_LANE0_SET + lane,
buf[lane]);
exynos_dp_write_bytes_to_dpcd(dp,
DPCD_ADDR_TRAINING_LANE0_SET,
lane_count,
dp->link_train.training_lane);
dev_info(dp->dev, "Link Training Clock Recovery success\n");
dp->link_train.lt_state = EQUALIZER_TRAINING;
} else {
for (lane = 0; lane < lane_count; lane++) {
training_lane = exynos_dp_get_lane_link_training(
dp, lane);
exynos_dp_read_bytes_from_dpcd(dp,
DPCD_ADDR_ADJUST_REQUEST_LANE0_1,
2, adjust_request);
voltage_swing = exynos_dp_get_adjust_request_voltage(
adjust_request, lane);
pre_emphasis = exynos_dp_get_adjust_request_pre_emphasis(
adjust_request, lane);
if (voltage_swing == VOLTAGE_LEVEL_3 ||
pre_emphasis == PRE_EMPHASIS_LEVEL_3) {
dev_err(dp->dev, "voltage or pre emphasis reached max level\n");
goto reduce_link_rate;
}
if ((DPCD_VOLTAGE_SWING_GET(training_lane) ==
voltage_swing) &&
(DPCD_PRE_EMPHASIS_GET(training_lane) ==
pre_emphasis)) {
dp->link_train.cr_loop[lane]++;
if (dp->link_train.cr_loop[lane] == MAX_CR_LOOP) {
dev_err(dp->dev, "CR Max loop\n");
goto reduce_link_rate;
}
}
training_lane = DPCD_VOLTAGE_SWING_SET(voltage_swing) |
DPCD_PRE_EMPHASIS_SET(pre_emphasis);
if (voltage_swing == VOLTAGE_LEVEL_3)
training_lane |= DPCD_MAX_SWING_REACHED;
if (pre_emphasis == PRE_EMPHASIS_LEVEL_3)
training_lane |= DPCD_MAX_PRE_EMPHASIS_REACHED;
dp->link_train.training_lane[lane] = training_lane;
exynos_dp_set_lane_link_training(dp,
dp->link_train.training_lane[lane], lane);
}
exynos_dp_write_bytes_to_dpcd(dp,
DPCD_ADDR_TRAINING_LANE0_SET,
lane_count,
dp->link_train.training_lane);
}
return 0;
reduce_link_rate:
exynos_dp_reduce_link_rate(dp);
return -EIO;
}
static int exynos_dp_process_equalizer_training(struct exynos_dp_device *dp)
{
u8 link_status[6];
u8 link_status[2];
u8 link_align[3];
int lane;
int lane_count;
u8 buf[5];
u32 reg;
u8 adjust_request[2];
u8 voltage_swing;
u8 pre_emphasis;
u8 training_lane;
usleep_range(400, 401);
exynos_dp_read_bytes_from_dpcd(dp, DPCD_ADDR_LANE0_1_STATUS,
6, link_status);
lane_count = dp->link_train.lane_count;
exynos_dp_read_bytes_from_dpcd(dp, DPCD_ADDR_LANE0_1_STATUS,
2, link_status);
if (exynos_dp_clock_recovery_ok(link_status, lane_count) == 0) {
adjust_request[0] = link_status[4];
adjust_request[1] = link_status[5];
link_align[0] = link_status[0];
link_align[1] = link_status[1];
exynos_dp_read_byte_from_dpcd(dp,
DPCD_ADDR_LANE_ALIGN_STATUS_UPDATED,
&link_align[2]);
for (lane = 0; lane < lane_count; lane++) {
exynos_dp_read_bytes_from_dpcd(dp,
DPCD_ADDR_ADJUST_REQUEST_LANE0_1,
2, adjust_request);
voltage_swing = exynos_dp_get_adjust_request_voltage(
adjust_request, lane);
pre_emphasis = exynos_dp_get_adjust_request_pre_emphasis(
adjust_request, lane);
training_lane = DPCD_VOLTAGE_SWING_SET(voltage_swing) |
DPCD_PRE_EMPHASIS_SET(pre_emphasis);
if (voltage_swing == VOLTAGE_LEVEL_3)
training_lane |= DPCD_MAX_SWING_REACHED;
if (pre_emphasis == PRE_EMPHASIS_LEVEL_3)
training_lane |= DPCD_MAX_PRE_EMPHASIS_REACHED;
dp->link_train.training_lane[lane] = training_lane;
}
if (exynos_dp_channel_eq_ok(link_status, lane_count) == 0) {
/* traing pattern Set to Normal */
@ -596,39 +599,42 @@ static int exynos_dp_process_equalizer_training(struct exynos_dp_device *dp)
dp->link_train.lane_count = reg;
dev_dbg(dp->dev, "final lane count = %.2x\n",
dp->link_train.lane_count);
/* set enhanced mode if available */
exynos_dp_set_enhanced_mode(dp);
dp->link_train.lt_state = FINISHED;
} else {
/* not all locked */
dp->link_train.eq_loop++;
if (dp->link_train.eq_loop > MAX_EQ_LOOP) {
exynos_dp_reduce_link_rate(dp);
} else {
exynos_dp_get_adjust_train(dp, adjust_request);
for (lane = 0; lane < lane_count; lane++) {
exynos_dp_set_lane_link_training(dp,
dp->link_train.training_lane[lane],
lane);
buf[lane] = dp->link_train.training_lane[lane];
exynos_dp_write_byte_to_dpcd(dp,
DPCD_ADDR_TRAINING_LANE0_SET + lane,
buf[lane]);
}
dev_err(dp->dev, "EQ Max loop\n");
goto reduce_link_rate;
}
for (lane = 0; lane < lane_count; lane++)
exynos_dp_set_lane_link_training(dp,
dp->link_train.training_lane[lane],
lane);
exynos_dp_write_bytes_to_dpcd(dp,
DPCD_ADDR_TRAINING_LANE0_SET,
lane_count,
dp->link_train.training_lane);
}
} else {
exynos_dp_reduce_link_rate(dp);
goto reduce_link_rate;
}
return 0;
reduce_link_rate:
exynos_dp_reduce_link_rate(dp);
return -EIO;
}
static void exynos_dp_get_max_rx_bandwidth(struct exynos_dp_device *dp,
u8 *bandwidth)
u8 *bandwidth)
{
u8 data;
@ -641,7 +647,7 @@ static void exynos_dp_get_max_rx_bandwidth(struct exynos_dp_device *dp,
}
static void exynos_dp_get_max_rx_lane_count(struct exynos_dp_device *dp,
u8 *lane_count)
u8 *lane_count)
{
u8 data;
@ -693,13 +699,7 @@ static void exynos_dp_init_training(struct exynos_dp_device *dp,
static int exynos_dp_sw_link_training(struct exynos_dp_device *dp)
{
int retval = 0;
int training_finished;
/* Turn off unnecessary lane */
if (dp->link_train.lane_count == 1)
exynos_dp_set_analog_power_down(dp, CH1_BLOCK, 1);
training_finished = 0;
int training_finished = 0;
dp->link_train.lt_state = START;
@ -710,10 +710,14 @@ static int exynos_dp_sw_link_training(struct exynos_dp_device *dp)
exynos_dp_link_start(dp);
break;
case CLOCK_RECOVERY:
exynos_dp_process_clock_recovery(dp);
retval = exynos_dp_process_clock_recovery(dp);
if (retval)
dev_err(dp->dev, "LT CR failed!\n");
break;
case EQUALIZER_TRAINING:
exynos_dp_process_equalizer_training(dp);
retval = exynos_dp_process_equalizer_training(dp);
if (retval)
dev_err(dp->dev, "LT EQ failed!\n");
break;
case FINISHED:
training_finished = 1;

2
drivers/video/exynos/exynos_dp_core.h
View file

@ -144,7 +144,7 @@ void exynos_dp_disable_scrambling(struct exynos_dp_device *dp);
#define DPCD_ADDR_TRAINING_PATTERN_SET 0x0102
#define DPCD_ADDR_TRAINING_LANE0_SET 0x0103
#define DPCD_ADDR_LANE0_1_STATUS 0x0202
#define DPCD_ADDR_LANE_ALIGN__STATUS_UPDATED 0x0204
#define DPCD_ADDR_LANE_ALIGN_STATUS_UPDATED 0x0204
#define DPCD_ADDR_ADJUST_REQUEST_LANE0_1 0x0206
#define DPCD_ADDR_ADJUST_REQUEST_LANE2_3 0x0207
#define DPCD_ADDR_TEST_REQUEST 0x0218