drm/msm/dp: allow voltage swing / pre emphasis of 3

[ 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>

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 fb588fde298a..780e9747be1f 100644
--- a/drivers/gpu/drm/msm/dp/dp_ctrl.c
+++ b/drivers/gpu/drm/msm/dp/dp_ctrl.c
@@ -1019,14 +1019,14 @@ 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);
@@ -1117,7 +1117,7 @@ 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 25950171caf3..a198af7b2d44 100644
--- a/drivers/gpu/drm/msm/dp/dp_link.c
+++ b/drivers/gpu/drm/msm/dp/dp_link.c
@@ -1141,6 +1141,7 @@ 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;
 
@@ -1172,30 +1173,29 @@ 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 9dd4dd926530..79c3a02b8dac 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;