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Subject[PATCH v3 5/6] drm: bridge/analogix: add fast link train for eDP
Date
From: zain wang <wzz@rock-chips.com>

we would meet a short black screen when exit PSR with the full link
training, In this case, we should use fast link train instead of full
link training.

Signed-off-by: zain wang <wzz@rock-chips.com>
---
drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 89 +++++++++++++++++++++-
drivers/gpu/drm/bridge/analogix/analogix_dp_core.h | 1 +
2 files changed, 86 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 561b644..0516621 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -21,6 +21,7 @@
#include <linux/gpio.h>
#include <linux/component.h>
#include <linux/phy/phy.h>
+#include <linux/iopoll.h>

#include <drm/drmP.h>
#include <drm/drm_atomic_helper.h>
@@ -35,6 +36,8 @@

#define to_dp(nm) container_of(nm, struct analogix_dp_device, nm)

+static const int FAST_LINK_VERIFICATION = false;
+
struct bridge_init {
struct i2c_client *client;
struct device_node *node;
@@ -244,6 +247,7 @@ static int analogix_dp_link_start(struct analogix_dp_device *dp)
usleep_range(90, 120);
}

+
/* Set training pattern 1 */
analogix_dp_set_training_pattern(dp, TRAINING_PTN1);

@@ -481,7 +485,7 @@ static int analogix_dp_process_equalizer_training(struct analogix_dp_device *dp)
{
int lane, lane_count, retval;
u32 reg;
- u8 link_align, link_status[2], adjust_request[2];
+ u8 link_align, link_status[2], adjust_request[2], spread;

usleep_range(400, 401);

@@ -524,6 +528,12 @@ static int analogix_dp_process_equalizer_training(struct analogix_dp_device *dp)
dev_dbg(dp->dev, "final lane count = %.2x\n",
dp->link_train.lane_count);

+ drm_dp_dpcd_readb(&dp->aux, DP_MAX_DOWNSPREAD, &spread);
+ dp->fast_train_support = (spread &
+ DP_NO_AUX_HANDSHAKE_LINK_TRAINING) ? true : false;
+ dev_dbg(dp->dev, "fast link training %s\n",
+ dp->fast_train_support ? "supported" : "unsupported");
+
/* set enhanced mode if available */
analogix_dp_set_enhanced_mode(dp);
dp->link_train.lt_state = FINISHED;
@@ -655,6 +665,75 @@ static int analogix_dp_sw_link_training(struct analogix_dp_device *dp)
return retval;
}

+static int analogix_dp_full_link_train(struct analogix_dp_device *dp,
+ u32 count, u32 bwtype)
+{
+ analogix_dp_init_training(dp, count, bwtype);
+ return analogix_dp_sw_link_training(dp);
+}
+
+static int analogix_dp_fast_link_train(struct analogix_dp_device *dp)
+{
+ int lane;
+ int retval;
+ u8 link_align, link_status[2];
+ enum pll_status status;
+
+ analogix_dp_reset_macro(dp);
+
+ analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate);
+ analogix_dp_set_lane_count(dp, dp->link_train.lane_count);
+
+ for (lane = 0; lane < dp->link_train.lane_count; lane++) {
+ analogix_dp_set_lane_link_training(dp,
+ dp->link_train.training_lane[lane], lane);
+ }
+
+ retval = readx_poll_timeout(analogix_dp_get_pll_lock_status, dp, status,
+ status != PLL_UNLOCKED,
+ 120, 120 * DP_TIMEOUT_LOOP_COUNT);
+
+ if (retval)
+ return retval;
+
+ /* source Set training pattern 1 */
+ analogix_dp_set_training_pattern(dp, TRAINING_PTN1);
+ usleep_range(500, 600);
+
+ analogix_dp_set_training_pattern(dp, TRAINING_PTN2);
+ usleep_range(500, 600);
+
+ /* TODO: enhanced_mode?*/
+ analogix_dp_set_training_pattern(dp, DP_NONE);
+
+ if (FAST_LINK_VERIFICATION) {
+ retval = drm_dp_dpcd_readb(&dp->aux,
+ DP_LANE_ALIGN_STATUS_UPDATED,
+ &link_align);
+ if (retval < 0)
+ return retval;
+
+ retval = drm_dp_dpcd_read(&dp->aux, DP_LANE0_1_STATUS,
+ link_status, 2);
+ if (retval < 0)
+ return retval;
+
+ if (analogix_dp_clock_recovery_ok(link_status,
+ dp->link_train.lane_count)) {
+ analogix_dp_reduce_link_rate(dp);
+ return -EIO;
+ }
+
+ if (analogix_dp_channel_eq_ok(link_status, link_align,
+ dp->link_train.lane_count)) {
+ analogix_dp_reduce_link_rate(dp);
+ return -EIO;
+ }
+ }
+
+ return 0;
+}
+
static int analogix_dp_set_link_train(struct analogix_dp_device *dp,
u32 count, u32 bwtype)
{
@@ -662,11 +741,13 @@ static int analogix_dp_set_link_train(struct analogix_dp_device *dp,
int retval;

for (i = 0; i < DP_TIMEOUT_LOOP_COUNT; i++) {
- analogix_dp_init_training(dp, count, bwtype);
- retval = analogix_dp_sw_link_training(dp);
+ if (dp->fast_train_support)
+ retval = analogix_dp_fast_link_train(dp);
+ else
+ retval = analogix_dp_full_link_train(dp, count,
+ bwtype);
if (retval == 0)
break;
-
usleep_range(100, 110);
}

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
index cdc0535..b86039b 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
@@ -171,6 +171,7 @@ struct analogix_dp_device {
int hpd_gpio;
bool force_hpd;
bool psr_support;
+ bool fast_train_support;

struct mutex panel_lock;
bool panel_is_modeset;
--
1.9.1

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