[PATCH 6.1 214/473] drm/msm/dp: allow voltage swing / pre emphasis of 3

Greg Kroah-Hartman
2024-06-06T14:15:32Z

From: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

[ Upstream commit 22578178e5dd6d3aa4490879df8b6c2977d980be ]

Both dp_link_adjust_levels() and dp_ctrl_update_vx_px() limit swing and
pre-emphasis to 2, while the real maximum value for the sum of the
voltage swing and pre-emphasis is 3. Fix the DP code to remove this
limitation.

Fixes: c943b4948b58 ("drm/msm/dp: add displayPort driver support")
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reviewed-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Tested-by: Kuogee Hsieh <quic_khsieh@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/577006/
Link: https://lore.kernel.org/r/20240203-dp-swing-3-v1-1-6545e1706196@linaro.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/gpu/drm/msm/dp/dp_ctrl.c | 6 +++---
drivers/gpu/drm/msm/dp/dp_link.c | 22 +++++++++++-----------
drivers/gpu/drm/msm/dp/dp_link.h | 14 +-------------
3 files changed, 15 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/msm/dp/dp_ctrl.c b/drivers/gpu/drm/msm/dp/dp_ctrl.c
index b20701893e5b3..2c501261f2323 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1014,14 +1014,14 @@ static int dp_ctrl_update_vx_px(struct dp_ctrl_private *ctrl)
if (ret)
return ret;

- if (voltage_swing_level >= DP_TRAIN_VOLTAGE_SWING_MAX) {
+ if (voltage_swing_level >= DP_TRAIN_LEVEL_MAX) {
drm_dbg_dp(ctrl->drm_dev,
"max. voltage swing level reached %d\n",
voltage_swing_level);
max_level_reached |= DP_TRAIN_MAX_SWING_REACHED;
}

- if (pre_emphasis_level >= DP_TRAIN_PRE_EMPHASIS_MAX) {
+ if (pre_emphasis_level >= DP_TRAIN_LEVEL_MAX) {
drm_dbg_dp(ctrl->drm_dev,
"max. pre-emphasis level reached %d\n",
pre_emphasis_level);
@@ -1112,7 +1112,7 @@ static int dp_ctrl_link_train_1(struct dp_ctrl_private *ctrl,
}

if (ctrl->link->phy_params.v_level >=
- DP_TRAIN_VOLTAGE_SWING_MAX) {
+ DP_TRAIN_LEVEL_MAX) {
DRM_ERROR_RATELIMITED("max v_level reached\n");
return -EAGAIN;
}
diff --git a/drivers/gpu/drm/msm/dp/dp_link.c b/drivers/gpu/drm/msm/dp/dp_link.c
index ceb382fa56d5b..e4f9decec970f 100644
--- a/drivers/gpu/drm/msm/dp/dp_link.c
+++ b/drivers/gpu/drm/msm/dp/dp_link.c
@@ -1102,6 +1102,7 @@ int dp_link_get_colorimetry_config(struct dp_link *dp_link)
int dp_link_adjust_levels(struct dp_link *dp_link, u8 *link_status)
{
int i;
+ u8 max_p_level;
int v_max = 0, p_max = 0;
struct dp_link_private *link;

@@ -1133,30 +1134,29 @@ int dp_link_adjust_levels(struct dp_link *dp_link, u8 *link_status)
* Adjust the voltage swing and pre-emphasis level combination to within
* the allowable range.
*/
- if (dp_link->phy_params.v_level > DP_TRAIN_VOLTAGE_SWING_MAX) {
+ if (dp_link->phy_params.v_level > DP_TRAIN_LEVEL_MAX) {
drm_dbg_dp(link->drm_dev,
"Requested vSwingLevel=%d, change to %d\n",
dp_link->phy_params.v_level,
- DP_TRAIN_VOLTAGE_SWING_MAX);
- dp_link->phy_params.v_level = DP_TRAIN_VOLTAGE_SWING_MAX;
+ DP_TRAIN_LEVEL_MAX);
+ dp_link->phy_params.v_level = DP_TRAIN_LEVEL_MAX;
}

- if (dp_link->phy_params.p_level > DP_TRAIN_PRE_EMPHASIS_MAX) {
+ if (dp_link->phy_params.p_level > DP_TRAIN_LEVEL_MAX) {
drm_dbg_dp(link->drm_dev,
"Requested preEmphasisLevel=%d, change to %d\n",
dp_link->phy_params.p_level,
- DP_TRAIN_PRE_EMPHASIS_MAX);
- dp_link->phy_params.p_level = DP_TRAIN_PRE_EMPHASIS_MAX;
+ DP_TRAIN_LEVEL_MAX);
+ dp_link->phy_params.p_level = DP_TRAIN_LEVEL_MAX;
}

- if ((dp_link->phy_params.p_level > DP_TRAIN_PRE_EMPHASIS_LVL_1)
- && (dp_link->phy_params.v_level ==
- DP_TRAIN_VOLTAGE_SWING_LVL_2)) {
+ max_p_level = DP_TRAIN_LEVEL_MAX - dp_link->phy_params.v_level;
+ if (dp_link->phy_params.p_level > max_p_level) {
drm_dbg_dp(link->drm_dev,
"Requested preEmphasisLevel=%d, change to %d\n",
dp_link->phy_params.p_level,
- DP_TRAIN_PRE_EMPHASIS_LVL_1);
- dp_link->phy_params.p_level = DP_TRAIN_PRE_EMPHASIS_LVL_1;
+ max_p_level);
+ dp_link->phy_params.p_level = max_p_level;
}

drm_dbg_dp(link->drm_dev, "adjusted: v_level=%d, p_level=%d\n",
diff --git a/drivers/gpu/drm/msm/dp/dp_link.h b/drivers/gpu/drm/msm/dp/dp_link.h
index 9dd4dd9265304..79c3a02b8dacd 100644
--- a/drivers/gpu/drm/msm/dp/dp_link.h
+++ b/drivers/gpu/drm/msm/dp/dp_link.h
@@ -19,19 +19,7 @@ struct dp_link_info {
unsigned long capabilities;
};

-enum dp_link_voltage_level {
- DP_TRAIN_VOLTAGE_SWING_LVL_0 = 0,
- DP_TRAIN_VOLTAGE_SWING_LVL_1 = 1,
- DP_TRAIN_VOLTAGE_SWING_LVL_2 = 2,
- DP_TRAIN_VOLTAGE_SWING_MAX = DP_TRAIN_VOLTAGE_SWING_LVL_2,
-};
-
-enum dp_link_preemaphasis_level {
- DP_TRAIN_PRE_EMPHASIS_LVL_0 = 0,
- DP_TRAIN_PRE_EMPHASIS_LVL_1 = 1,
- DP_TRAIN_PRE_EMPHASIS_LVL_2 = 2,
- DP_TRAIN_PRE_EMPHASIS_MAX = DP_TRAIN_PRE_EMPHASIS_LVL_2,
-};
+#define DP_TRAIN_LEVEL_MAX 3

struct dp_link_test_video {
u32 test_video_pattern;
--
2.43.0