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Subject[PATCH 11/40] drm/bridge: analogix_dp: 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>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Thierry Escande <thierry.escande@collabora.com>
---
drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 142 ++++++++++++++++-----
drivers/gpu/drm/bridge/analogix/analogix_dp_core.h | 3 +
2 files changed, 114 insertions(+), 31 deletions(-)

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
index 84141571e960..e0775adf80b3 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c
@@ -10,17 +10,18 @@
* option) any later version.
*/

-#include <linux/module.h>
-#include <linux/platform_device.h>
-#include <linux/err.h>
#include <linux/clk.h>
-#include <linux/io.h>
+#include <linux/component.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_gpio.h>
-#include <linux/gpio.h>
-#include <linux/component.h>
#include <linux/phy/phy.h>
+#include <linux/platform_device.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 bool verify_fast_training;
+
struct bridge_init {
struct i2c_client *client;
struct device_node *node;
@@ -528,7 +531,7 @@ 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);

@@ -571,6 +574,20 @@ 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);

+ retval = drm_dp_dpcd_readb(&dp->aux, DP_MAX_DOWNSPREAD,
+ &spread);
+ if (retval != 1) {
+ dev_err(dp->dev, "failed to read downspread %d\n",
+ retval);
+ dp->fast_train_support = false;
+ } else {
+ 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;
@@ -627,10 +644,12 @@ static void analogix_dp_get_max_rx_lane_count(struct analogix_dp_device *dp,
*lane_count = DPCD_MAX_LANE_COUNT(data);
}

-static void analogix_dp_init_training(struct analogix_dp_device *dp,
- enum link_lane_count_type max_lane,
- int max_rate)
+static int analogix_dp_full_link_train(struct analogix_dp_device *dp,
+ u32 max_lanes, u32 max_rate)
{
+ int retval = 0;
+ bool training_finished = false;
+
/*
* MACRO_RST must be applied after the PLL_LOCK to avoid
* the DP inter pair skew issue for at least 10 us
@@ -656,18 +675,13 @@ static void analogix_dp_init_training(struct analogix_dp_device *dp,
}

/* Setup TX lane count & rate */
- if (dp->link_train.lane_count > max_lane)
- dp->link_train.lane_count = max_lane;
+ if (dp->link_train.lane_count > max_lanes)
+ dp->link_train.lane_count = max_lanes;
if (dp->link_train.link_rate > max_rate)
dp->link_train.link_rate = max_rate;

/* All DP analog module power up */
analogix_dp_set_analog_power_down(dp, POWER_ALL, 0);
-}
-
-static int analogix_dp_sw_link_training(struct analogix_dp_device *dp)
-{
- int retval = 0, training_finished = 0;

dp->link_train.lt_state = START;

@@ -702,22 +716,88 @@ static int analogix_dp_sw_link_training(struct analogix_dp_device *dp)
return retval;
}

-static int analogix_dp_set_link_train(struct analogix_dp_device *dp,
- u32 count, u32 bwtype)
+static int analogix_dp_fast_link_train(struct analogix_dp_device *dp)
{
- int i;
- int retval;
+ int i, ret;
+ u8 link_align, link_status[2];
+ enum pll_status status;

- for (i = 0; i < DP_TIMEOUT_LOOP_COUNT; i++) {
- analogix_dp_init_training(dp, count, bwtype);
- retval = analogix_dp_sw_link_training(dp);
- if (retval == 0)
- break;
+ analogix_dp_reset_macro(dp);

- usleep_range(100, 110);
+ analogix_dp_set_link_bandwidth(dp, dp->link_train.link_rate);
+ analogix_dp_set_lane_count(dp, dp->link_train.lane_count);
+
+ for (i = 0; i < dp->link_train.lane_count; i++) {
+ analogix_dp_set_lane_link_training(dp,
+ dp->link_train.training_lane[i], i);
}

- return retval;
+ ret = readx_poll_timeout(analogix_dp_get_pll_lock_status, dp, status,
+ status != PLL_UNLOCKED, 120,
+ 120 * DP_TIMEOUT_LOOP_COUNT);
+ if (ret) {
+ DRM_DEV_ERROR(dp->dev, "Wait for pll lock failed %d\n", ret);
+ return ret;
+ }
+
+ /* source Set training pattern 1 */
+ analogix_dp_set_training_pattern(dp, TRAINING_PTN1);
+ /* From DP spec, pattern must be on-screen for a minimum 500us */
+ usleep_range(500, 600);
+
+ analogix_dp_set_training_pattern(dp, TRAINING_PTN2);
+ /* From DP spec, pattern must be on-screen for a minimum 500us */
+ usleep_range(500, 600);
+
+ /* TODO: enhanced_mode?*/
+ analogix_dp_set_training_pattern(dp, DP_NONE);
+
+ /*
+ * Useful for debugging issues with fast link training, disable for more
+ * speed
+ */
+ if (verify_fast_training) {
+ ret = drm_dp_dpcd_readb(&dp->aux, DP_LANE_ALIGN_STATUS_UPDATED,
+ &link_align);
+ if (ret < 0) {
+ DRM_DEV_ERROR(dp->dev, "Read align status failed %d\n",
+ ret);
+ return ret;
+ }
+
+ ret = drm_dp_dpcd_read(&dp->aux, DP_LANE0_1_STATUS, link_status,
+ 2);
+ if (ret < 0) {
+ DRM_DEV_ERROR(dp->dev, "Read link status failed %d\n",
+ ret);
+ return ret;
+ }
+
+ if (analogix_dp_clock_recovery_ok(link_status,
+ dp->link_train.lane_count)) {
+ DRM_DEV_ERROR(dp->dev, "Clock recovery failed\n");
+ analogix_dp_reduce_link_rate(dp);
+ return -EIO;
+ }
+
+ if (analogix_dp_channel_eq_ok(link_status, link_align,
+ dp->link_train.lane_count)) {
+ DRM_DEV_ERROR(dp->dev, "Channel EQ failed\n");
+ analogix_dp_reduce_link_rate(dp);
+ return -EIO;
+ }
+ }
+
+ return 0;
+}
+
+static int analogix_dp_train_link(struct analogix_dp_device *dp)
+{
+ if (dp->fast_train_support)
+ return analogix_dp_fast_link_train(dp);
+
+ return analogix_dp_full_link_train(dp, dp->video_info.max_lane_count,
+ dp->video_info.max_link_rate);
}

static int analogix_dp_config_video(struct analogix_dp_device *dp)
@@ -850,10 +930,10 @@ static void analogix_dp_commit(struct analogix_dp_device *dp)
DRM_ERROR("failed to disable the panel\n");
}

- ret = analogix_dp_set_link_train(dp, dp->video_info.max_lane_count,
- dp->video_info.max_link_rate);
+ ret = readx_poll_timeout(analogix_dp_train_link, dp, ret, !ret, 100,
+ DP_TIMEOUT_TRAINING_US * 5);
if (ret) {
- dev_err(dp->dev, "unable to do link train\n");
+ dev_err(dp->dev, "unable to do link train, ret=%d\n", ret);
return;
}

diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
index e135a42cb19e..920607d7eb3e 100644
--- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
+++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.h
@@ -20,6 +20,8 @@
#define MAX_CR_LOOP 5
#define MAX_EQ_LOOP 5

+/* Training takes 22ms if AUX channel comm fails. Use this as retry interval */
+#define DP_TIMEOUT_TRAINING_US 22000
#define DP_TIMEOUT_PSR_LOOP_MS 300

/* DP_MAX_LANE_COUNT */
@@ -171,6 +173,7 @@ struct analogix_dp_device {
int hpd_gpio;
bool force_hpd;
bool psr_enable;
+ bool fast_train_support;

struct mutex panel_lock;
bool panel_is_modeset;
--
2.14.1
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