Merge patch series "scsi: ufs: Add support for static TX Equalization settings"

Can Guo <can.guo@oss.qualcomm.com> says:

Hi,

This series adds support for board-specific static TX Equalization settings
provided through Device Tree.

This series is based on the earlier TX Equalization enablement work and
persistent storage/retrieval of optimal TX Equalization settings work:
https://lore.kernel.org/all/20260325152154.1604082-1-can.guo@oss.qualcomm.com
https://lore.kernel.org/all/20260424151420.111675-1-can.guo@oss.qualcomm.com

Background
==========

UFS v5.0/UFSHCI v5.0 adds HS-G6 support (46.6 Gbps/lane) via UniPro v3.0
and M-PHY v6.0. These specs define TX Equalization for all High-Speed
Gears (not only HS-G6) to compensate channel loss and improve signal
integrity at high speed.

For HS-G6, M-PHY uses PAM4 1b1b line coding. Pre-Coding may also be
required depending on channel characteristics.

This series adds vendor-neutral DT properties:
- patternProperties: txeq-preshoot-g[1-6], txeq-deemphasis-g[1-6]
- fixed property: tx-precode-enable-g6

All properties use per-lane Host/Device tuples and accept 2 or 4 values
for x1/x2 lane configurations:
- txeq-preshoot-g[1-6]: values 0..7
- txeq-deemphasis-g[1-6]: values 0..7
- tx-precode-enable-g6: values 0/1

These properties carry board-level SI characterization data used as static
TX Equalization settings for each High-Speed Gear.

Example DTS snippet
===================

The following x2-lane example shows the expected DT encoding:

	ufs@1d84000 {
		lanes-per-direction = <2>;

		txeq-preshoot-g6 = <1 2>, <3 4>;
		txeq-deemphasis-g6 = <0 1>, <2 3>;
		tx-precode-enable-g6 = <1 0>, <0 1>;
	};

Relationship with Adaptive TX Equalization
==========================================

Adaptive TX Equalization remains the primary path when enabled.

Static TX Equalization settings from DT are board-specific baseline values,
but when adaptive TX Equalization is used, static settings are not final:
- If valid settings are retrieved from qTxEQGnSettings/wTxEQGnSettingsExt,
  those retrieved settings override static DT settings.
- If retrieval is not available/valid, TX EQTR runs and trained settings
  override static DT settings.

So static DT settings are a fallback and are intended for cases where
adaptive TX Equalization is not enabled/used.

No behavior changes for platforms that do not provide these properties.

What this series adds
=====================

1. dt-bindings:
- Document txeq-preshoot-g[1-6], txeq-deemphasis-g[1-6], and
  tx-precode-enable-g6 in ufs-common.yaml.
- Define tuple encoding for host/device values per lane.
- Add per-property value validation ranges in schema.

2. UFS core/platform integration:
- Parse and validate per-gear DT TX EQ settings during platform init.
- Store parsed values into per-gear TX EQ params and track DT origin using
  the from_dt flag.
- Integrate static-state handling in TX EQ flow so DT-provided entries are
  fed through the adaptive TX Equalization path and then converted to
  normal runtime params.

Link: https://patch.msgid.link/20260616113348.1168248-1-can.guo@oss.qualcomm.com
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

4 files changed, 228 insertions, 1 deletions

diff --git a/Documentation/devicetree/bindings/ufs/ufs-common.yaml b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
index ed97f5682509..cc32e1189d50 100644
--- a/Documentation/devicetree/bindings/ufs/ufs-common.yaml
+++ b/Documentation/devicetree/bindings/ufs/ufs-common.yaml
@@ -105,6 +105,64 @@ properties:
       Restricts the UFS controller to rate-a or rate-b for both TX and
       RX directions.
 
+  tx-precode-enable-g6:
+    $ref: /schemas/types.yaml#/definitions/uint32-matrix
+    minItems: 1
+    items:
+      - items:
+          - description: Host_Lane0 precode
+            enum: [0, 1]
+          - description: Device_Lane0 precode
+            enum: [0, 1]
+      - items:
+          - description: Host_Lane1 precode
+            enum: [0, 1]
+          - description: Device_Lane1 precode
+            enum: [0, 1]
+    description:
+      Static TX Precode enable values for HS-G6 only.
+
+patternProperties:
+  "^txeq-preshoot-g[1-6]$":
+    $ref: /schemas/types.yaml#/definitions/uint32-matrix
+    minItems: 1
+    items:
+      - items:
+          - description: Host_Lane0 Preshoot value
+            enum: [0, 1, 2, 3, 4, 5, 6, 7]
+          - description: Device_Lane0 Preshoot value
+            enum: [0, 1, 2, 3, 4, 5, 6, 7]
+      - items:
+          - description: Host_Lane1 Preshoot value
+            enum: [0, 1, 2, 3, 4, 5, 6, 7]
+          - description: Device_Lane1 Preshoot value
+            enum: [0, 1, 2, 3, 4, 5, 6, 7]
+    description: |
+      Static TX Equalization PreShoot settings for High Speed Gears. These
+      values are programmed to the corresponding UniPro PA layer attribute
+      PA_TxEQG[1-6]Setting. Each value selects a Pre-Shoot level as defined
+      by the MIPI M-PHY specification (TX_HS_PreShoot_Setting).
+
+  "^txeq-deemphasis-g[1-6]$":
+    $ref: /schemas/types.yaml#/definitions/uint32-matrix
+    minItems: 1
+    items:
+      - items:
+          - description: Host_Lane0 DeEmphasis value
+            enum: [0, 1, 2, 3, 4, 5, 6, 7]
+          - description: Device_Lane0 DeEmphasis value
+            enum: [0, 1, 2, 3, 4, 5, 6, 7]
+      - items:
+          - description: Host_Lane1 DeEmphasis value
+            enum: [0, 1, 2, 3, 4, 5, 6, 7]
+          - description: Device_Lane1 DeEmphasis value
+            enum: [0, 1, 2, 3, 4, 5, 6, 7]
+    description: |
+      Static TX Equalization DeEmphasis settings for High Speed Gears. These
+      values are programmed to the corresponding UniPro PA layer attribute
+      PA_TxEQG[1-6]Setting. Each value selects a De-Emphasis level as defined
+      by the MIPI M-PHY specification (TX_HS_DeEmphasis_Setting).
+
 dependencies:
   freq-table-hz: [ clocks ]
   operating-points-v2: [ clocks, clock-names ]
diff --git a/drivers/ufs/core/ufs-txeq.c b/drivers/ufs/core/ufs-txeq.c
index aa64f2bf4f1e..f06dc3c3492d 100644
--- a/drivers/ufs/core/ufs-txeq.c
+++ b/drivers/ufs/core/ufs-txeq.c
@@ -1301,7 +1301,13 @@ int ufshcd_config_tx_eq_settings(struct ufs_hba *hba,
 	}
 
 	params = &hba->tx_eq_params[gear - 1];
-	if (!params->is_valid || force_tx_eqtr) {
+	/*
+	 * TX EQTR must run for the following cases:
+	 * 1. TX EQ settings are invalid.
+	 * 2. TX EQ settings are from Device Tree.
+	 * 3. TX EQTR procedure is forced.
+	 */
+	if (!params->is_valid || params->from_dt || force_tx_eqtr) {
 		int ret;
 
 		ret = ufshcd_tx_eqtr(hba, params, pwr_mode);
@@ -1314,6 +1320,8 @@ int ufshcd_config_tx_eq_settings(struct ufs_hba *hba,
 		/* Mark TX Equalization settings as valid */
 		params->is_valid = true;
 		params->is_trained = true;
+		/* TX EQTR succeeds, clear from_dt flag */
+		params->from_dt = false;
 		params->is_applied = false;
 	}
 
@@ -1499,6 +1507,11 @@ static void ufshcd_extract_tx_eq_settings_attrs(struct ufs_hba *hba, u8 gear)
 	}
 
 	params->is_valid = true;
+	/*
+	 * Optimal TX EQ settings are retrieved from UFS device attributes,
+	 * clear from_dt flag to avoid TX EQTR procedure.
+	 */
+	params->from_dt = false;
 }
 
 void ufshcd_retrieve_tx_eq_settings(struct ufs_hba *hba)
diff --git a/drivers/ufs/host/ufshcd-pltfrm.c b/drivers/ufs/host/ufshcd-pltfrm.c
index c2dafb583cf5..5ac7afe75934 100644
--- a/drivers/ufs/host/ufshcd-pltfrm.c
+++ b/drivers/ufs/host/ufshcd-pltfrm.c
@@ -210,6 +210,158 @@ static void ufshcd_init_lanes_per_dir(struct ufs_hba *hba)
 	}
 }
 
+static int ufshcd_parse_tx_precode_enable(struct ufs_hba *hba,
+					  bool host_precode_en[UFS_MAX_LANES],
+					  bool device_precode_en[UFS_MAX_LANES])
+{
+	const char *prop_name = "tx-precode-enable-g6";
+	u32 num_elems = 2 * hba->lanes_per_direction;
+	const u32 lpd = hba->lanes_per_direction;
+	u32 precode[UFS_MAX_LANES * 2];
+	struct device *dev = hba->dev;
+	int count, err, i;
+
+	count = of_property_count_u32_elems(dev->of_node, prop_name);
+	if (count == -EINVAL || count == -ENODATA)
+		return 0;
+
+	if (count < 0)
+		return count;
+
+	if (count != num_elems) {
+		dev_err(dev, "Property %s has invalid count (%d), expecting %u\n",
+			prop_name, count, num_elems);
+		return -EINVAL;
+	}
+
+	err = of_property_read_u32_array(dev->of_node, prop_name, precode, num_elems);
+	if (err) {
+		dev_err(dev, "Failed to read %s property, %d\n", prop_name, err);
+		return err;
+	}
+
+	for (i = 0; i < num_elems; i++) {
+		if (precode[i] > 1) {
+			dev_err(dev, "Invalid TX precode value (%u) in %s property\n",
+				precode[i], prop_name);
+			return -EINVAL;
+		}
+	}
+
+	for (i = 0; i < lpd; i++) {
+		host_precode_en[i] = precode[i * 2];
+		device_precode_en[i] = precode[i * 2 + 1];
+	}
+
+	return 0;
+}
+
+static int ufshcd_parse_tx_eq_value_array(struct ufs_hba *hba,
+					  const char *prop_name,
+					  const u32 max_value,
+					  u32 values[UFS_MAX_LANES * 2])
+{
+	u32 num_elems = 2 * hba->lanes_per_direction;
+	struct device *dev = hba->dev;
+	int count, err, i;
+
+	count = of_property_count_u32_elems(dev->of_node, prop_name);
+	if (count < 0)
+		return count;
+
+	if (count != num_elems) {
+		dev_err(dev, "Property %s has invalid count (%d), expecting %u\n",
+			prop_name, count, num_elems);
+		return -EINVAL;
+	}
+
+	err = of_property_read_u32_array(dev->of_node, prop_name, values, num_elems);
+	if (err) {
+		dev_err(dev, "Failed to read %s property, %d\n", prop_name, err);
+		return err;
+	}
+
+	for (i = 0; i < num_elems; i++) {
+		if (values[i] >= max_value) {
+			dev_err(dev, "Invalid TX EQ value (%u) in %s property\n",
+				values[i], prop_name);
+			return -EINVAL;
+		}
+	}
+
+	return 0;
+}
+
+/**
+ * ufshcd_parse_tx_eq_settings_for_gear - Parse static TX EQ DT settings for one gear
+ * @hba: per adapter instance
+ * @gear: target HS gear
+ *
+ * Reads the txeq-preshoot-gN, txeq-deemphasis-gN, and (for G6)
+ * tx-precode-enable-g6 device-tree properties.
+ * If all present values are valid, stores them as static TX Equalization
+ * settings for the given gear.
+ */
+static void ufshcd_parse_tx_eq_settings_for_gear(struct ufs_hba *hba, int gear)
+{
+	bool device_precode_en[UFS_MAX_LANES] = { false };
+	bool host_precode_en[UFS_MAX_LANES] = { false };
+	const u32 lpd = hba->lanes_per_direction;
+	struct ufshcd_tx_eq_params *params;
+	u32 deemphasis[UFS_MAX_LANES * 2];
+	u32 preshoot[UFS_MAX_LANES * 2];
+	char prop_name[MAX_PROP_SIZE];
+	int err, lane;
+
+	snprintf(prop_name, MAX_PROP_SIZE, "txeq-preshoot-g%d", gear);
+	err = ufshcd_parse_tx_eq_value_array(hba, prop_name, TX_HS_NUM_PRESHOOT, preshoot);
+	if (err)
+		return;
+
+	snprintf(prop_name, MAX_PROP_SIZE, "txeq-deemphasis-g%d", gear);
+	err = ufshcd_parse_tx_eq_value_array(hba, prop_name, TX_HS_NUM_DEEMPHASIS, deemphasis);
+	if (err)
+		return;
+
+	if (gear == UFS_HS_G6) {
+		err = ufshcd_parse_tx_precode_enable(hba, host_precode_en, device_precode_en);
+		if (err)
+			return;
+	}
+
+	params = &hba->tx_eq_params[gear - 1];
+	for (lane = 0; lane < lpd; lane++) {
+		params->host[lane].preshoot = preshoot[lane * 2];
+		params->host[lane].deemphasis = deemphasis[lane * 2];
+		params->host[lane].precode_en = host_precode_en[lane];
+
+		params->device[lane].preshoot = preshoot[lane * 2 + 1];
+		params->device[lane].deemphasis = deemphasis[lane * 2 + 1];
+		params->device[lane].precode_en = device_precode_en[lane];
+	}
+
+	params->is_valid = true;
+	params->from_dt = true;
+}
+
+static void ufshcd_parse_static_tx_eq_settings(struct ufs_hba *hba)
+{
+	const u32 lpd = hba->lanes_per_direction;
+	int gear;
+
+	if (!lpd)
+		return;
+
+	if (lpd > UFS_MAX_LANES) {
+		dev_warn(hba->dev, "lanes_per_direction (%u) exceeds UFS_MAX_LANES (%u)\n",
+			 lpd, UFS_MAX_LANES);
+		return;
+	}
+
+	for (gear = UFS_HS_G1; gear <= UFS_HS_GEAR_MAX; gear++)
+		ufshcd_parse_tx_eq_settings_for_gear(hba, gear);
+}
+
 /**
  * ufshcd_parse_clock_min_max_freq  - Parse MIN and MAX clocks freq
  * @hba: per adapter instance
@@ -528,6 +680,8 @@ int ufshcd_pltfrm_init(struct platform_device *pdev,
 
 	ufshcd_init_lanes_per_dir(hba);
 
+	ufshcd_parse_static_tx_eq_settings(hba);
+
 	err = ufshcd_parse_operating_points(hba);
 	if (err) {
 		dev_err(dev, "%s: OPP parse failed %d\n", __func__, err);
diff --git a/include/ufs/ufshcd.h b/include/ufs/ufshcd.h
index 248d0a5bef40..f96a97fbd314 100644
--- a/include/ufs/ufshcd.h
+++ b/include/ufs/ufshcd.h
@@ -359,6 +359,7 @@ struct ufshcd_tx_eqtr_record {
  * @is_valid: True if parameter contains valid TX Equalization settings
  * @is_applied: True if settings have been applied to UniPro of both sides
  * @is_trained: True if parameters obtained from TX EQTR procedure
+ * @from_dt: True if settings are from Device Tree
  */
 struct ufshcd_tx_eq_params {
 	struct ufshcd_tx_eq_settings host[UFS_MAX_LANES];
@@ -367,6 +368,7 @@ struct ufshcd_tx_eq_params {
 	bool is_valid;
 	bool is_applied;
 	bool is_trained;
+	bool from_dt;
 };
 
 /**