On Tue, Oct 22, 2024 at 08:41:46PM +0800, Yongbang Shi wrote:
From: baihan li <libaihan@xxxxxxxxxx>
Add link training process functions in this moduel.
We should probably have a bounty for a developer who finally writes a
generic DP link training helpers.
Signed-off-by: baihan li <libaihan@xxxxxxxxxx>
Missing SoB
---
ChangeLog:
v1 -> v2:
- using drm_dp_* functions implement dp link training process, suggested by Jani Nikula.
- fix build errors reported by kernel test robot <lkp@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-kbuild-all/202410031735.8iRZZR6T-lkp@xxxxxxxxx/
v1:https://lore.kernel.org/all/20240930100610.782363-1-shiyongbang@xxxxxxxxxx/
---
drivers/gpu/drm/hisilicon/hibmc/Makefile | 2 +-
drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c | 344 +++++++++++++++++++
drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.h | 25 ++
3 files changed, 370 insertions(+), 1 deletion(-)
create mode 100644 drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
create mode 100644 drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.h
diff --git a/drivers/gpu/drm/hisilicon/hibmc/Makefile b/drivers/gpu/drm/hisilicon/hibmc/Makefile
index 8770ec6dfffd..94d77da88bbf 100644
--- a/drivers/gpu/drm/hisilicon/hibmc/Makefile
+++ b/drivers/gpu/drm/hisilicon/hibmc/Makefile
@@ -1,5 +1,5 @@
# SPDX-License-Identifier: GPL-2.0-only
hibmc-drm-y := hibmc_drm_drv.o hibmc_drm_de.o hibmc_drm_vdac.o hibmc_drm_i2c.o \
- dp/dp_aux.o
+ dp/dp_aux.o dp/dp_link.o
obj-$(CONFIG_DRM_HISI_HIBMC) += hibmc-drm.o
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
new file mode 100644
index 000000000000..b02a536e0689
--- /dev/null
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.c
@@ -0,0 +1,344 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+// Copyright (c) 2024 Hisilicon Limited.
+
+#include <linux/delay.h>
+#include <drm/drm_device.h>
+#include <drm/drm_print.h>
+#include "dp_comm.h"
+#include "dp_reg.h"
+#include "dp_link.h"
+#include "dp_aux.h"
+
+const u8 link_rate_map[] = {DP_LINK_BW_1_62, DP_LINK_BW_2_7,
+ DP_LINK_BW_5_4, DP_LINK_BW_8_1};
+
+static int dp_link_training_configure(struct dp_dev *dp)
+{
+ u8 buf[2];
+ int ret;
+
+ /* DP 2 lane */
+ dp_write_bits(dp->base + DP_PHYIF_CTRL0, DP_CFG_LANE_DATA_EN,
+ dp->link.cap.lanes == DP_LANE_NUM_2 ? 0x3 : 0x1);
+ dp_write_bits(dp->base + DP_DPTX_GCTL0, DP_CFG_PHY_LANE_NUM,
+ dp->link.cap.lanes == DP_LANE_NUM_2 ? 0x1 : 0);
+
+ /* enhanced frame */
+ dp_write_bits(dp->base + DP_VIDEO_CTRL, DP_CFG_STREAM_FRAME_MODE, 0x1);
+
+ /* set rate and lane count */
+ buf[0] = dp_get_link_rate(dp->link.cap.link_rate);
+ buf[1] = DP_LANE_COUNT_ENHANCED_FRAME_EN | dp->link.cap.lanes;
+ ret = drm_dp_dpcd_write(&dp->aux, DP_LINK_BW_SET, buf, sizeof(buf));
+ if (ret != sizeof(buf)) {
+ drm_err(dp->dev, "dp aux write link rate and lanes failed, ret: %d\n", ret);
+ return ret;
+ }
+
+ /* set 8b/10b and downspread */
+ buf[0] = 0x10;
+ buf[1] = 0x1;
+ ret = drm_dp_dpcd_write(&dp->aux, DP_DOWNSPREAD_CTRL, buf, sizeof(buf));
+ if (ret != sizeof(buf))
+ drm_err(dp->dev, "dp aux write 8b/10b and downspread failed, ret: %d\n", ret);
+
+ ret = drm_dp_read_dpcd_caps(&dp->aux, dp->dpcd);
+ if (ret)
+ drm_err(dp->dev, "dp aux read dpcd failed, ret: %d\n", ret);
+
+ return ret;
+}
+
+static int dp_link_pattern2dpcd(struct dp_dev *dp, enum dp_pattern_e pattern)
+{
+ switch (pattern) {
+ case DP_PATTERN_NO:
+ return DP_TRAINING_PATTERN_DISABLE;
+ case DP_PATTERN_TPS1:
+ return DP_TRAINING_PATTERN_1;
+ case DP_PATTERN_TPS2:
+ return DP_TRAINING_PATTERN_2;
+ case DP_PATTERN_TPS3:
+ return DP_TRAINING_PATTERN_3;
+ case DP_PATTERN_TPS4:
+ return DP_TRAINING_PATTERN_4;
+ default:
+ drm_err(dp->dev, "dp link unknown pattern %d\n", pattern);
+ return -EINVAL;
Why do you need the extra defines / wrappers? Can you use
DP_TRAINING_PATTERN_foo directly?
+ }
+}
+
+static int dp_link_set_pattern(struct dp_dev *dp, enum dp_pattern_e pattern)
+{
+ int ret;
+ u8 buf;
+
+ ret = dp_link_pattern2dpcd(dp, pattern);
+ if (ret < 0)
+ return ret;
+
+ buf = (u8)ret;
+ if (pattern != DP_TRAINING_PATTERN_DISABLE && pattern != DP_TRAINING_PATTERN_4) {
+ buf |= DP_LINK_SCRAMBLING_DISABLE;
+ dp_write_bits(dp->base + DP_PHYIF_CTRL0, DP_CFG_SCRAMBLE_EN, 0x1);
+ } else {
+ dp_write_bits(dp->base + DP_PHYIF_CTRL0, DP_CFG_SCRAMBLE_EN, 0);
+ }
+
+ dp_write_bits(dp->base + DP_PHYIF_CTRL0, DP_CFG_PAT_SEL, pattern);
+
+ ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_PATTERN_SET, &buf, sizeof(buf));
+ if (ret != sizeof(buf))
+ drm_err(dp->dev, "dp aux write training pattern set failed\n");
+
+ return 0;
+}
+
+static int dp_link_training_cr_pre(struct dp_dev *dp)
+{
+ u8 *train_set = dp->link.train_set;
+ int ret;
+ u8 i;
+
+ ret = dp_link_training_configure(dp);
+ if (ret)
+ return ret;
+
+ ret = dp_link_set_pattern(dp, DP_PATTERN_TPS1);
+ if (ret)
+ return ret;
+
+ for (i = 0; i < dp->link.cap.lanes; i++)
+ train_set[i] = DP_TRAIN_VOLTAGE_SWING_LEVEL_2;
+
+ ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET, train_set, dp->link.cap.lanes);
+ if (ret != dp->link.cap.lanes)
+ drm_err(dp->dev, "dp aux write training lane set failed\n");
+
+ return 0;
+}
+
+static bool dp_link_get_adjust_train(struct dp_dev *dp, u8 lane_status[DP_LINK_STATUS_SIZE])
+{
+ u8 pre_emph[DP_LANE_NUM_MAX] = {0};
+ u8 voltage[DP_LANE_NUM_MAX] = {0};
+ bool changed = false;
+ u8 train_set;
+ u8 lane;
+
+ /* not support level 3 */
??
+ for (lane = 0; lane < dp->link.cap.lanes; lane++) {
+ voltage[lane] = drm_dp_get_adjust_request_voltage(lane_status, lane);
+ pre_emph[lane] = drm_dp_get_adjust_request_pre_emphasis(lane_status, lane);
+ }
+
+ for (lane = 0; lane < dp->link.cap.lanes; lane++) {
+ train_set = voltage[lane] | pre_emph[lane];
+ if (dp->link.train_set[lane] != train_set) {
+ changed = true;
+ dp->link.train_set[lane] = train_set;
+ }
+ }
+
+ return changed;
+}
+
+u8 dp_get_link_rate(u8 index)
+{
+ return link_rate_map[index];
+}
Use the array directly
+
+static int dp_link_reduce_rate(struct dp_dev *dp)
+{
+ if (dp->link.cap.link_rate > 0) {
+ dp->link.cap.link_rate--;
+ return 0;
+ }
+
+ drm_err(dp->dev, "dp link training reduce rate failed, already lowest rate\n");
+
+ return -EFAULT;
EFAULT => "Bad address". Probably the error code should be slightly
different.
+}
+
+static int dp_link_reduce_lane(struct dp_dev *dp)
+{
+ if (dp->link.cap.lanes == DP_LANE_NUM_1) {
+ drm_err(dp->dev, "dp link training reduce lane failed, already reach minimum\n");
+ return -EFAULT;
+ }
+
+ /* currently only 1 lane */
You've probably meant "1 or 2 lanes". Still a switchcase might be
better.
+ dp->link.cap.lanes = DP_LANE_NUM_1;
+
+ return 0;
+}
+
+static int dp_link_training_cr(struct dp_dev *dp)
+{
+ u8 lane_status[DP_LINK_STATUS_SIZE] = {0};
+ bool level_changed;
+ u32 voltage_tries;
+ u32 cr_tries;
+ u32 max_cr;
+ int ret;
+
+ /*
+ * DP 1.4 spec define 10 for maxtries value, for pre DP 1.4 version set a limit of 80
+ * (4 voltage levels x 4 preemphasis levels x 5 identical voltage retries)
+ */
+ max_cr = dp->link.cap.rx_dpcd_revision >= DPCD_REVISION_14 ? 10 : 80;
+
+ voltage_tries = 1;
+ for (cr_tries = 0; cr_tries < max_cr; cr_tries++) {
+ drm_dp_link_train_clock_recovery_delay(&dp->aux, dp->dpcd);
+
+ ret = drm_dp_dpcd_read_link_status(&dp->aux, lane_status);
+ if (ret != DP_LINK_STATUS_SIZE) {
+ drm_err(dp->dev, "Get lane status failed\n");
+ return ret;
+ }
+
+ if (drm_dp_clock_recovery_ok(lane_status, dp->link.cap.lanes)) {
+ drm_info(dp->dev, "dp link training cr done\n");
+ dp->link.status.clock_recovered = true;
+ return 0;
+ }
+
+ if (voltage_tries == 5) {
+ drm_info(dp->dev, "same voltage tries 5 times\n");
+ dp->link.status.clock_recovered = false;
+ return 0;
+ }
+
+ level_changed = dp_link_get_adjust_train(dp, lane_status);
+ ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET, dp->link.train_set,
+ dp->link.cap.lanes);
+ if (ret != dp->link.cap.lanes) {
+ drm_err(dp->dev, "Update link training failed\n");
+ return ret;
+ }
+
+ voltage_tries = level_changed ? 1 : voltage_tries + 1;
+ }
+
+ drm_err(dp->dev, "dp link training clock recovery %u timers failed\n", max_cr);
+ dp->link.status.clock_recovered = false;
+
+ return 0;
+}
+
+static int dp_link_training_channel_eq(struct dp_dev *dp)
+{
+ u8 lane_status[DP_LINK_STATUS_SIZE] = {0};
+ enum dp_pattern_e tps;
+ u8 eq_tries;
+ int ret;
+
+ if (dp->link.cap.is_tps4)
+ tps = DP_PATTERN_TPS4;
+ else if (dp->link.cap.is_tps3)
+ tps = DP_PATTERN_TPS3;
+ else
+ tps = DP_PATTERN_TPS2;
+
+ ret = dp_link_set_pattern(dp, tps);
+ if (ret)
+ return ret;
+
+ for (eq_tries = 0; eq_tries < EQ_MAX_RETRY; eq_tries++) {
+ drm_dp_link_train_channel_eq_delay(&dp->aux, dp->dpcd);
+
+ ret = drm_dp_dpcd_read_link_status(&dp->aux, lane_status);
+ if (ret != DP_LINK_STATUS_SIZE) {
+ drm_err(dp->dev, "get lane status failed\n");
+ break;
+ }
+
+ if (!drm_dp_clock_recovery_ok(lane_status, dp->link.cap.lanes)) {
+ drm_info(dp->dev, "clock recovery check failed\n");
+ drm_info(dp->dev, "cannot continue channel equalization\n");
+ dp->link.status.clock_recovered = false;
+ break;
+ }
+
+ if (drm_dp_channel_eq_ok(lane_status, dp->link.cap.lanes)) {
+ dp->link.status.channel_equalized = true;
+ drm_info(dp->dev, "dp link training eq done\n");
+ break;
+ }
+
+ dp_link_get_adjust_train(dp, lane_status);
+ ret = drm_dp_dpcd_write(&dp->aux, DP_TRAINING_LANE0_SET,
+ dp->link.train_set, dp->link.cap.lanes);
+ if (ret != dp->link.cap.lanes) {
+ drm_err(dp->dev, "Update link training failed\n");
+ break;
+ }
+ }
+
+ if (eq_tries == EQ_MAX_RETRY)
+ drm_err(dp->dev, "channel equalization failed %u times\n", eq_tries);
+
+ dp_link_set_pattern(dp, DP_PATTERN_NO);
+
+ return ret < 0 ? ret : 0;
+}
+
+static int dp_link_downgrade_training_cr(struct dp_dev *dp)
+{
+ if (dp_link_reduce_rate(dp))
+ return dp_link_reduce_lane(dp);
+
+ return 0;
+}
+
+static int dp_link_downgrade_training_eq(struct dp_dev *dp)
+{
+ if ((dp->link.status.clock_recovered && !dp->link.status.channel_equalized)) {
+ if (!dp_link_reduce_lane(dp))
+ return 0;
+ }
+
+ return dp_link_reduce_rate(dp);
+}
+
+int dp_link_training(struct dp_dev *dp)
+{
+ struct hibmc_dp_link *link = &dp->link;
+ int ret;
+
+ while (true) {
+ ret = dp_link_training_cr_pre(dp);
+ if (ret)
+ goto err;
+
+ ret = dp_link_training_cr(dp);
+ if (ret)
+ goto err;
+
+ if (!link->status.clock_recovered) {
+ ret = dp_link_downgrade_training_cr(dp);
+ if (ret)
+ goto err;
+ continue;
+ }
+
+ ret = dp_link_training_channel_eq(dp);
+ if (ret)
+ goto err;
+
+ if (!link->status.channel_equalized) {
+ ret = dp_link_downgrade_training_eq(dp);
+ if (ret)
+ goto err;
+ continue;
+ }
+
+ return 0;
+ }
+
+err:
+ dp_link_set_pattern(dp, DP_PATTERN_NO);
+
+ return ret;
+}
diff --git a/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.h b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.h
new file mode 100644
index 000000000000..38877d8f473b
--- /dev/null
+++ b/drivers/gpu/drm/hisilicon/hibmc/dp/dp_link.h
@@ -0,0 +1,25 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/* Copyright (c) 2024 Hisilicon Limited. */
+
+#ifndef DP_LINK_H
+#define DP_LINK_H
+
+#include "dp_comm.h"
+
+#define DP_LANE_NUM_MAX 2
+#define DP_LANE_STATUS_SIZE 1
+#define DP_LANE_NUM_1 0x1
+#define DP_LANE_NUM_2 0x2
+
+enum dp_pattern_e {
+ DP_PATTERN_NO = 0,
+ DP_PATTERN_TPS1,
+ DP_PATTERN_TPS2,
+ DP_PATTERN_TPS3,
+ DP_PATTERN_TPS4,
+};
+
+int dp_link_training(struct dp_dev *dp);
+u8 dp_get_link_rate(u8 index);
+
+#endif
--
2.33.0
