[PATCH 0/4] thunderbolt: Improve software receiver lane margining

[PATCH 0/4] thunderbolt: Improve software receiver lane margining

[Mika Westerberg]

Hi all,

This series improves the software receiver lane margining support in
debugfs so that it should be more usable now.

Aapo Vienamo (1):
  thunderbolt: Add missing usb4_port_sb_read() to usb4_port_sw_margin()

R Kannappan (1):
  thunderbolt: Improve software receiver lane margining

Rene Sapiens (2):
  thunderbolt: Consolidate margining parameters into a structure
  thunderbolt: Add optional voltage offset range for receiver lane margining

 drivers/thunderbolt/debugfs.c | 381 ++++++++++++++++++++++++++++++++--
 drivers/thunderbolt/sb_regs.h |  18 +-
 drivers/thunderbolt/tb.h      |  42 +++-
 drivers/thunderbolt/usb4.c    |  62 +++---
 4 files changed, 451 insertions(+), 52 deletions(-)

-- 
2.43.0

[PATCH 1/4] thunderbolt: Add missing usb4_port_sb_read() to usb4_port_sw_margin()

[Mika Westerberg]

From: Aapo Vienamo <aapo.vienamo@linux.intel.com>

Synchronize the operation completion by reading back the software
margining operation completion metadata into margining->results.

Signed-off-by: Aapo Vienamo <aapo.vienamo@linux.intel.com>
Co-developed-by: R Kannappan <r.kannappan@intel.com>
Signed-off-by: R Kannappan <r.kannappan@intel.com>
Co-developed-by: Rene Sapiens <rene.sapiens@intel.com>
Signed-off-by: Rene Sapiens <rene.sapiens@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/thunderbolt/debugfs.c |  5 ++---
 drivers/thunderbolt/tb.h      |  2 +-
 drivers/thunderbolt/usb4.c    | 13 ++++++++++---
 3 files changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/thunderbolt/debugfs.c b/drivers/thunderbolt/debugfs.c
index 9ed4bb2e8d05..a0d07887990e 100644
--- a/drivers/thunderbolt/debugfs.c
+++ b/drivers/thunderbolt/debugfs.c
@@ -785,9 +785,8 @@ static int margining_run_write(void *data, u64 val)
 			    margining->time ? "time" : "voltage", dev_name(dev),
 			    margining->lanes);
 		ret = usb4_port_sw_margin(port, margining->target, margining->index,
-					  margining->lanes, margining->time,
-					  margining->right_high,
-					  USB4_MARGIN_SW_COUNTER_CLEAR);
+					  margining->lanes, margining->time, margining->right_high,
+					  USB4_MARGIN_SW_COUNTER_CLEAR, &margining->results[0]);
 		if (ret)
 			goto out_clx;
 
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index b47f7873c847..321db4076573 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -1360,7 +1360,7 @@ int usb4_port_hw_margin(struct tb_port *port, enum usb4_sb_target target,
 			bool timing, bool right_high, u32 *results);
 int usb4_port_sw_margin(struct tb_port *port, enum usb4_sb_target target,
 			u8 index, unsigned int lanes, bool timing,
-			bool right_high, u32 counter);
+			bool right_high, u32 counter, u32 *results);
 int usb4_port_sw_margin_errors(struct tb_port *port, enum usb4_sb_target target,
 			       u8 index, u32 *errors);
 
diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index 4d83b65afb5b..5505aa95c2ea 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -1703,6 +1703,7 @@ int usb4_port_hw_margin(struct tb_port *port, enum usb4_sb_target target,
  * @timing: Perform timing margining instead of voltage
  * @right_high: Use Right/high margin instead of left/low
  * @counter: What to do with the error counter
+ * @results: Data word for the operation completion data
  *
  * Runs software lane margining on USB4 port. Read back the error
  * counters by calling usb4_port_sw_margin_errors(). Returns %0 in
@@ -1710,7 +1711,7 @@ int usb4_port_hw_margin(struct tb_port *port, enum usb4_sb_target target,
  */
 int usb4_port_sw_margin(struct tb_port *port, enum usb4_sb_target target,
 			u8 index, unsigned int lanes, bool timing,
-			bool right_high, u32 counter)
+			bool right_high, u32 counter, u32 *results)
 {
 	u32 val;
 	int ret;
@@ -1728,8 +1729,14 @@ int usb4_port_sw_margin(struct tb_port *port, enum usb4_sb_target target,
 	if (ret)
 		return ret;
 
-	return usb4_port_sb_op(port, target, index,
-			       USB4_SB_OPCODE_RUN_SW_LANE_MARGINING, 2500);
+	ret = usb4_port_sb_op(port, target, index,
+			      USB4_SB_OPCODE_RUN_SW_LANE_MARGINING, 2500);
+	if (ret)
+		return ret;
+
+	return usb4_port_sb_read(port, target, index, USB4_SB_DATA, results,
+				 sizeof(*results));
+
 }
 
 /**
-- 
2.43.0

[PATCH 2/4] thunderbolt: Consolidate margining parameters into a structure

[Mika Westerberg]

From: Rene Sapiens <rene.sapiens@intel.com>

Consolidate the hardware and software margining parameters into a single
structure to reduce the number of parameters passed to the margining
functions.

Signed-off-by: Rene Sapiens <rene.sapiens@intel.com>
Co-developed-by: Aapo Vienamo <aapo.vienamo@linux.intel.com>
Signed-off-by: Aapo Vienamo <aapo.vienamo@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/thunderbolt/debugfs.c | 32 +++++++++++++++++-------
 drivers/thunderbolt/sb_regs.h |  5 ----
 drivers/thunderbolt/tb.h      | 38 ++++++++++++++++++++++++++---
 drivers/thunderbolt/usb4.c    | 46 ++++++++++++++++-------------------
 4 files changed, 78 insertions(+), 43 deletions(-)

diff --git a/drivers/thunderbolt/debugfs.c b/drivers/thunderbolt/debugfs.c
index a0d07887990e..5d1588baea6a 100644
--- a/drivers/thunderbolt/debugfs.c
+++ b/drivers/thunderbolt/debugfs.c
@@ -780,13 +780,20 @@ static int margining_run_write(void *data, u64 val)
 	}
 
 	if (margining->software) {
+		struct usb4_port_margining_params params = {
+			.error_counter = USB4_MARGIN_SW_ERROR_COUNTER_CLEAR,
+			.lanes = margining->lanes,
+			.time = margining->time,
+			.right_high = margining->right_high,
+		};
+
 		tb_port_dbg(port,
 			    "running software %s lane margining for %s lanes %u\n",
 			    margining->time ? "time" : "voltage", dev_name(dev),
 			    margining->lanes);
-		ret = usb4_port_sw_margin(port, margining->target, margining->index,
-					  margining->lanes, margining->time, margining->right_high,
-					  USB4_MARGIN_SW_COUNTER_CLEAR, &margining->results[0]);
+
+		ret = usb4_port_sw_margin(port, margining->target, margining->index, &params,
+					  &margining->results[0]);
 		if (ret)
 			goto out_clx;
 
@@ -794,16 +801,23 @@ static int margining_run_write(void *data, u64 val)
 						 margining->index,
 						 &margining->results[0]);
 	} else {
+		struct usb4_port_margining_params params = {
+			.ber_level = margining->ber_level,
+			.lanes = margining->lanes,
+			.time = margining->time,
+			.right_high = margining->right_high,
+		};
+
+		/* Clear the results */
+		margining->results[0] = 0;
+		margining->results[1] = 0;
+
 		tb_port_dbg(port,
 			    "running hardware %s lane margining for %s lanes %u\n",
 			    margining->time ? "time" : "voltage", dev_name(dev),
 			    margining->lanes);
-		/* Clear the results */
-		margining->results[0] = 0;
-		margining->results[1] = 0;
-		ret = usb4_port_hw_margin(port, margining->target, margining->index,
-					  margining->lanes, margining->ber_level,
-					  margining->time, margining->right_high,
+
+		ret = usb4_port_hw_margin(port, margining->target, margining->index, &params,
 					  margining->results);
 	}
 
diff --git a/drivers/thunderbolt/sb_regs.h b/drivers/thunderbolt/sb_regs.h
index 2a88edfc97b2..86e80aa297f7 100644
--- a/drivers/thunderbolt/sb_regs.h
+++ b/drivers/thunderbolt/sb_regs.h
@@ -85,10 +85,5 @@ enum usb4_sb_opcode {
 #define USB4_MARGIN_SW_TIME			BIT(3)
 #define USB4_MARGIN_SW_RH			BIT(4)
 #define USB4_MARGIN_SW_COUNTER_MASK		GENMASK(14, 13)
-#define USB4_MARGIN_SW_COUNTER_SHIFT		13
-#define USB4_MARGIN_SW_COUNTER_NOP		0x0
-#define USB4_MARGIN_SW_COUNTER_CLEAR		0x1
-#define USB4_MARGIN_SW_COUNTER_START		0x2
-#define USB4_MARGIN_SW_COUNTER_STOP		0x3
 
 #endif
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 321db4076573..89ea66f885a4 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -1353,14 +1353,44 @@ int usb4_port_sb_read(struct tb_port *port, enum usb4_sb_target target, u8 index
 int usb4_port_sb_write(struct tb_port *port, enum usb4_sb_target target,
 		       u8 index, u8 reg, const void *buf, u8 size);
 
+/**
+ * enum usb4_margin_sw_error_counter - Software margining error counter operation
+ * @USB4_MARGIN_SW_ERROR_COUNTER_NOP: No change in counter setup
+ * @USB4_MARGIN_SW_ERROR_COUNTER_CLEAR: Set the error counter to 0, enable counter
+ * @USB4_MARGIN_SW_ERROR_COUNTER_START: Start counter, count from last value
+ * @USB4_MARGIN_SW_ERROR_COUNTER_STOP: Stop counter, do not clear value
+ */
+enum usb4_margin_sw_error_counter {
+	USB4_MARGIN_SW_ERROR_COUNTER_NOP,
+	USB4_MARGIN_SW_ERROR_COUNTER_CLEAR,
+	USB4_MARGIN_SW_ERROR_COUNTER_START,
+	USB4_MARGIN_SW_ERROR_COUNTER_STOP,
+};
+
+/**
+ * struct usb4_port_margining_params - USB4 margining parameters
+ * @error_counter: Error counter operation for software margining
+ * @ber_level: Current BER level contour value
+ * @lanes: %0, %1 or %7 (all)
+ * @right_high: %false if left/low margin test is performed, %true if right/high
+ * @time: %true if time margining is used instead of voltage
+ */
+struct usb4_port_margining_params {
+	enum usb4_margin_sw_error_counter error_counter;
+	u32 ber_level;
+	u32 lanes;
+	bool right_high;
+	bool time;
+};
+
 int usb4_port_margining_caps(struct tb_port *port, enum usb4_sb_target target,
 			     u8 index, u32 *caps);
 int usb4_port_hw_margin(struct tb_port *port, enum usb4_sb_target target,
-			u8 index, unsigned int lanes, unsigned int ber_level,
-			bool timing, bool right_high, u32 *results);
+			u8 index, const struct usb4_port_margining_params *params,
+			u32 *results);
 int usb4_port_sw_margin(struct tb_port *port, enum usb4_sb_target target,
-			u8 index, unsigned int lanes, bool timing,
-			bool right_high, u32 counter, u32 *results);
+			u8 index, const struct usb4_port_margining_params *params,
+			u32 *results);
 int usb4_port_sw_margin_errors(struct tb_port *port, enum usb4_sb_target target,
 			       u8 index, u32 *errors);
 
diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index 5505aa95c2ea..cb51cafcf20c 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -1653,31 +1653,29 @@ int usb4_port_margining_caps(struct tb_port *port, enum usb4_sb_target target,
  * @port: USB4 port
  * @target: Sideband target
  * @index: Retimer index if taget is %USB4_SB_TARGET_RETIMER
- * @lanes: Which lanes to run (must match the port capabilities). Can be
- *	   %0, %1 or %7.
- * @ber_level: BER level contour value
- * @timing: Perform timing margining instead of voltage
- * @right_high: Use Right/high margin instead of left/low
+ * @params: Parameters for USB4 hardware margining
  * @results: Array with at least two elements to hold the results
  *
  * Runs hardware lane margining on USB4 port and returns the result in
  * @results.
  */
 int usb4_port_hw_margin(struct tb_port *port, enum usb4_sb_target target,
-			u8 index, unsigned int lanes, unsigned int ber_level,
-			bool timing, bool right_high, u32 *results)
+			u8 index, const struct usb4_port_margining_params *params,
+			u32 *results)
 {
 	u32 val;
 	int ret;
 
-	val = lanes;
-	if (timing)
+	if (WARN_ON_ONCE(!params))
+		return -EINVAL;
+
+	val = params->lanes;
+	if (params->time)
 		val |= USB4_MARGIN_HW_TIME;
-	if (right_high)
+	if (params->right_high)
 		val |= USB4_MARGIN_HW_RH;
-	if (ber_level)
-		val |= (ber_level << USB4_MARGIN_HW_BER_SHIFT) &
-			USB4_MARGIN_HW_BER_MASK;
+	if (params->ber_level)
+		val |= FIELD_PREP(USB4_MARGIN_HW_BER_MASK, params->ber_level);
 
 	ret = usb4_port_sb_write(port, target, index, USB4_SB_METADATA, &val,
 				 sizeof(val));
@@ -1698,11 +1696,7 @@ int usb4_port_hw_margin(struct tb_port *port, enum usb4_sb_target target,
  * @port: USB4 port
  * @target: Sideband target
  * @index: Retimer index if taget is %USB4_SB_TARGET_RETIMER
- * @lanes: Which lanes to run (must match the port capabilities). Can be
- *	   %0, %1 or %7.
- * @timing: Perform timing margining instead of voltage
- * @right_high: Use Right/high margin instead of left/low
- * @counter: What to do with the error counter
+ * @params: Parameters for USB4 software margining
  * @results: Data word for the operation completion data
  *
  * Runs software lane margining on USB4 port. Read back the error
@@ -1710,19 +1704,21 @@ int usb4_port_hw_margin(struct tb_port *port, enum usb4_sb_target target,
  * success and negative errno otherwise.
  */
 int usb4_port_sw_margin(struct tb_port *port, enum usb4_sb_target target,
-			u8 index, unsigned int lanes, bool timing,
-			bool right_high, u32 counter, u32 *results)
+			u8 index, const struct usb4_port_margining_params *params,
+			u32 *results)
 {
 	u32 val;
 	int ret;
 
-	val = lanes;
-	if (timing)
+	if (WARN_ON_ONCE(!params))
+		return -EINVAL;
+
+	val = params->lanes;
+	if (params->time)
 		val |= USB4_MARGIN_SW_TIME;
-	if (right_high)
+	if (params->right_high)
 		val |= USB4_MARGIN_SW_RH;
-	val |= (counter << USB4_MARGIN_SW_COUNTER_SHIFT) &
-		USB4_MARGIN_SW_COUNTER_MASK;
+	val |= FIELD_PREP(USB4_MARGIN_SW_COUNTER_MASK, params->error_counter);
 
 	ret = usb4_port_sb_write(port, target, index, USB4_SB_METADATA, &val,
 				 sizeof(val));
-- 
2.43.0

[PATCH 3/4] thunderbolt: Add optional voltage offset range for receiver lane margining

[Mika Westerberg]

From: Rene Sapiens <rene.sapiens@intel.com>

Add optional extended voltage offset range support for software and
hardware margining as defined by the USB4 specification.

If supported, it can be enabled like below:

 # cd /sys/kernel/debug/thunderbolt/ROUTER/portX/margining/
 # echo Y > optional_voltage_offset

Signed-off-by: Rene Sapiens <rene.sapiens@intel.com>
Co-developed-by: R Kannappan <r.kannappan@intel.com>
Signed-off-by: R Kannappan <r.kannappan@intel.com>
Co-developed-by: Aapo Vienamo <aapo.vienamo@linux.intel.com>
Signed-off-by: Aapo Vienamo <aapo.vienamo@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/thunderbolt/debugfs.c | 74 +++++++++++++++++++++++++++++++++++
 drivers/thunderbolt/sb_regs.h |  5 +++
 drivers/thunderbolt/tb.h      |  2 +
 drivers/thunderbolt/usb4.c    |  4 ++
 4 files changed, 85 insertions(+)

diff --git a/drivers/thunderbolt/debugfs.c b/drivers/thunderbolt/debugfs.c
index 5d1588baea6a..9defa69ef3a7 100644
--- a/drivers/thunderbolt/debugfs.c
+++ b/drivers/thunderbolt/debugfs.c
@@ -394,8 +394,12 @@ static ssize_t retimer_sb_regs_write(struct file *file,
  * @ber_level: Current BER level contour value
  * @voltage_steps: Number of mandatory voltage steps
  * @max_voltage_offset: Maximum mandatory voltage offset (in mV)
+ * @voltage_steps_optional_range: Number of voltage steps for optional range
+ * @max_voltage_offset_optional_range: Maximum voltage offset for the optional
+ *					range (in mV).
  * @time_steps: Number of time margin steps
  * @max_time_offset: Maximum time margin offset (in mUI)
+ * @optional_voltage_offset_range: Enable optional extended voltage range
  * @software: %true if software margining is used instead of hardware
  * @time: %true if time margining is used instead of voltage
  * @right_high: %false if left/low margin test is performed, %true if
@@ -414,8 +418,11 @@ struct tb_margining {
 	unsigned int ber_level;
 	unsigned int voltage_steps;
 	unsigned int max_voltage_offset;
+	unsigned int voltage_steps_optional_range;
+	unsigned int max_voltage_offset_optional_range;
 	unsigned int time_steps;
 	unsigned int max_time_offset;
+	bool optional_voltage_offset_range;
 	bool software;
 	bool time;
 	bool right_high;
@@ -454,6 +461,12 @@ independent_time_margins(const struct tb_margining *margining)
 	return FIELD_GET(USB4_MARGIN_CAP_1_TIME_INDP_MASK, margining->caps[1]);
 }
 
+static bool
+supports_optional_voltage_offset_range(const struct tb_margining *margining)
+{
+	return margining->caps[0] & USB4_MARGIN_CAP_0_OPT_VOLTAGE_SUPPORT;
+}
+
 static ssize_t
 margining_ber_level_write(struct file *file, const char __user *user_buf,
 			   size_t count, loff_t *ppos)
@@ -553,6 +566,14 @@ static int margining_caps_show(struct seq_file *s, void *not_used)
 		   margining->voltage_steps);
 	seq_printf(s, "# maximum voltage offset: %u mV\n",
 		   margining->max_voltage_offset);
+	seq_printf(s, "# optional voltage offset range support: %s\n",
+		   str_yes_no(supports_optional_voltage_offset_range(margining)));
+	if (supports_optional_voltage_offset_range(margining)) {
+		seq_printf(s, "# voltage margin steps, optional range: %u\n",
+			   margining->voltage_steps_optional_range);
+		seq_printf(s, "# maximum voltage offset, optional range: %u mV\n",
+			   margining->max_voltage_offset_optional_range);
+	}
 
 	switch (independent_voltage_margins(margining)) {
 	case USB4_MARGIN_CAP_0_VOLTAGE_MIN:
@@ -667,6 +688,42 @@ static int margining_lanes_show(struct seq_file *s, void *not_used)
 }
 DEBUGFS_ATTR_RW(margining_lanes);
 
+static ssize_t
+margining_optional_voltage_offset_write(struct file *file,
+				   const char __user *user_buf,
+				   size_t count, loff_t *ppos)
+{
+	struct seq_file *s = file->private_data;
+	struct tb_margining *margining = s->private;
+	struct tb *tb = margining->port->sw->tb;
+	bool val;
+	int ret;
+
+	ret = kstrtobool_from_user(user_buf, count, &val);
+	if (ret)
+		return ret;
+
+	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &tb->lock) {
+		margining->optional_voltage_offset_range = val;
+	}
+
+	return count;
+}
+
+static int margining_optional_voltage_offset_show(struct seq_file *s,
+						  void *not_used)
+{
+	struct tb_margining *margining = s->private;
+	struct tb *tb = margining->port->sw->tb;
+
+	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &tb->lock) {
+		seq_printf(s, "%u\n", margining->optional_voltage_offset_range);
+	}
+
+	return 0;
+}
+DEBUGFS_ATTR_RW(margining_optional_voltage_offset);
+
 static ssize_t margining_mode_write(struct file *file,
 				   const char __user *user_buf,
 				   size_t count, loff_t *ppos)
@@ -785,6 +842,7 @@ static int margining_run_write(void *data, u64 val)
 			.lanes = margining->lanes,
 			.time = margining->time,
 			.right_high = margining->right_high,
+			.optional_voltage_offset_range = margining->optional_voltage_offset_range,
 		};
 
 		tb_port_dbg(port,
@@ -806,6 +864,7 @@ static int margining_run_write(void *data, u64 val)
 			.lanes = margining->lanes,
 			.time = margining->time,
 			.right_high = margining->right_high,
+			.optional_voltage_offset_range = margining->optional_voltage_offset_range,
 		};
 
 		/* Clear the results */
@@ -865,6 +924,8 @@ static void voltage_margin_show(struct seq_file *s,
 	if (val & USB4_MARGIN_HW_RES_1_EXCEEDS)
 		seq_puts(s, " exceeds maximum");
 	seq_puts(s, "\n");
+	if (margining->optional_voltage_offset_range)
+		seq_puts(s, " optional voltage offset range enabled\n");
 }
 
 static void time_margin_show(struct seq_file *s,
@@ -1104,6 +1165,15 @@ static struct tb_margining *margining_alloc(struct tb_port *port,
 	val = FIELD_GET(USB4_MARGIN_CAP_0_MAX_VOLTAGE_OFFSET_MASK, margining->caps[0]);
 	margining->max_voltage_offset = 74 + val * 2;
 
+	if (supports_optional_voltage_offset_range(margining)) {
+		val = FIELD_GET(USB4_MARGIN_CAP_0_VOLT_STEPS_OPT_MASK,
+				margining->caps[0]);
+		margining->voltage_steps_optional_range = val;
+		val = FIELD_GET(USB4_MARGIN_CAP_1_MAX_VOLT_OFS_OPT_MASK,
+				margining->caps[1]);
+		margining->max_voltage_offset_optional_range = 74 + val * 2;
+	}
+
 	if (supports_time(margining)) {
 		val = FIELD_GET(USB4_MARGIN_CAP_1_TIME_STEPS_MASK, margining->caps[1]);
 		margining->time_steps = val;
@@ -1140,6 +1210,10 @@ static struct tb_margining *margining_alloc(struct tb_port *port,
 	     independent_time_margins(margining) == USB4_MARGIN_CAP_1_TIME_LR))
 		debugfs_create_file("margin", 0600, dir, margining,
 				    &margining_margin_fops);
+
+	if (supports_optional_voltage_offset_range(margining))
+		debugfs_create_file("optional_voltage_offset", DEBUGFS_MODE, dir, margining,
+				    &margining_optional_voltage_offset_fops);
 	return margining;
 }
 
diff --git a/drivers/thunderbolt/sb_regs.h b/drivers/thunderbolt/sb_regs.h
index 86e80aa297f7..8bff0740222c 100644
--- a/drivers/thunderbolt/sb_regs.h
+++ b/drivers/thunderbolt/sb_regs.h
@@ -57,6 +57,9 @@ enum usb4_sb_opcode {
 #define USB4_MARGIN_CAP_0_TIME			BIT(5)
 #define USB4_MARGIN_CAP_0_VOLTAGE_STEPS_MASK	GENMASK(12, 6)
 #define USB4_MARGIN_CAP_0_MAX_VOLTAGE_OFFSET_MASK GENMASK(18, 13)
+#define USB4_MARGIN_CAP_0_OPT_VOLTAGE_SUPPORT	BIT(19)
+#define USB4_MARGIN_CAP_0_VOLT_STEPS_OPT_MASK	GENMASK(26, 20)
+#define USB4_MARGIN_CAP_1_MAX_VOLT_OFS_OPT_MASK GENMASK(7, 0)
 #define USB4_MARGIN_CAP_1_TIME_DESTR		BIT(8)
 #define USB4_MARGIN_CAP_1_TIME_INDP_MASK	GENMASK(10, 9)
 #define USB4_MARGIN_CAP_1_TIME_MIN		0x0
@@ -72,6 +75,7 @@ enum usb4_sb_opcode {
 #define USB4_MARGIN_HW_RH			BIT(4)
 #define USB4_MARGIN_HW_BER_MASK			GENMASK(9, 5)
 #define USB4_MARGIN_HW_BER_SHIFT		5
+#define USB4_MARGIN_HW_OPT_VOLTAGE		BIT(10)
 
 /* Applicable to all margin values */
 #define USB4_MARGIN_HW_RES_1_MARGIN_MASK	GENMASK(6, 0)
@@ -84,6 +88,7 @@ enum usb4_sb_opcode {
 /* USB4_SB_OPCODE_RUN_SW_LANE_MARGINING */
 #define USB4_MARGIN_SW_TIME			BIT(3)
 #define USB4_MARGIN_SW_RH			BIT(4)
+#define USB4_MARGIN_SW_OPT_VOLTAGE		BIT(5)
 #define USB4_MARGIN_SW_COUNTER_MASK		GENMASK(14, 13)
 
 #endif
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 89ea66f885a4..262c333924b8 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -1372,6 +1372,7 @@ enum usb4_margin_sw_error_counter {
  * @error_counter: Error counter operation for software margining
  * @ber_level: Current BER level contour value
  * @lanes: %0, %1 or %7 (all)
+ * @optional_voltage_offset_range: Enable optional extended voltage range
  * @right_high: %false if left/low margin test is performed, %true if right/high
  * @time: %true if time margining is used instead of voltage
  */
@@ -1379,6 +1380,7 @@ struct usb4_port_margining_params {
 	enum usb4_margin_sw_error_counter error_counter;
 	u32 ber_level;
 	u32 lanes;
+	bool optional_voltage_offset_range;
 	bool right_high;
 	bool time;
 };
diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index cb51cafcf20c..a2f81e17ad8d 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -1676,6 +1676,8 @@ int usb4_port_hw_margin(struct tb_port *port, enum usb4_sb_target target,
 		val |= USB4_MARGIN_HW_RH;
 	if (params->ber_level)
 		val |= FIELD_PREP(USB4_MARGIN_HW_BER_MASK, params->ber_level);
+	if (params->optional_voltage_offset_range)
+		val |= USB4_MARGIN_HW_OPT_VOLTAGE;
 
 	ret = usb4_port_sb_write(port, target, index, USB4_SB_METADATA, &val,
 				 sizeof(val));
@@ -1716,6 +1718,8 @@ int usb4_port_sw_margin(struct tb_port *port, enum usb4_sb_target target,
 	val = params->lanes;
 	if (params->time)
 		val |= USB4_MARGIN_SW_TIME;
+	if (params->optional_voltage_offset_range)
+		val |= USB4_MARGIN_SW_OPT_VOLTAGE;
 	if (params->right_high)
 		val |= USB4_MARGIN_SW_RH;
 	val |= FIELD_PREP(USB4_MARGIN_SW_COUNTER_MASK, params->error_counter);
-- 
2.43.0

[PATCH 4/4] thunderbolt: Improve software receiver lane margining

[Mika Westerberg]

From: R Kannappan <r.kannappan@intel.com>

USB4 specification defines the metadata needed to perform software
margining, as well as the necessary steps which include waiting for
dwell time.

- Add dwell_time attribute to set the wait time while performing
  margining and checking for link errors.
- Add error_counter attribute to configure error counter prior to
  margining test.
- Add voltage_time_offset attribute to set the voltage or time offset
  steps before performing the software margining test.
- Perform software margining test for dwell duration, break if there are
  link errors, stop the clocks and provide results.

Below is a minimalistic example how this can be used. Note these values
are just examples. The exact values in practice depend on host specific
capabilities and the type of measurement to be performed.

  # cd /sys/kernel/debug/thunderbolt/ROUTER/portX/margining/
  # echo software > mode
  # echo 400 > dwell_time
  # echo 1 > run

As usual the results attribute contains the results of a succesfull run.

Signed-off-by: R Kannappan <r.kannappan@intel.com>
Co-developed-by: Rene Sapiens <rene.sapiens@intel.com>
Signed-off-by: Rene Sapiens <rene.sapiens@intel.com>
Co-developed-by: Aapo Vienamo <aapo.vienamo@linux.intel.com>
Signed-off-by: Aapo Vienamo <aapo.vienamo@linux.intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/thunderbolt/debugfs.c | 294 ++++++++++++++++++++++++++++++++--
 drivers/thunderbolt/sb_regs.h |   8 +
 drivers/thunderbolt/tb.h      |   2 +
 drivers/thunderbolt/usb4.c    |   1 +
 4 files changed, 289 insertions(+), 16 deletions(-)

diff --git a/drivers/thunderbolt/debugfs.c b/drivers/thunderbolt/debugfs.c
index 9defa69ef3a7..208a95c475c2 100644
--- a/drivers/thunderbolt/debugfs.c
+++ b/drivers/thunderbolt/debugfs.c
@@ -9,6 +9,7 @@
 
 #include <linux/bitfield.h>
 #include <linux/debugfs.h>
+#include <linux/delay.h>
 #include <linux/pm_runtime.h>
 #include <linux/uaccess.h>
 
@@ -34,6 +35,14 @@
 
 #define COUNTER_SET_LEN		3
 
+/*
+ * USB4 spec doesn't specify dwell range, the range of 100 ms to 500 ms
+ * probed to give good results.
+ */
+#define MIN_DWELL_TIME		100 /* ms */
+#define MAX_DWELL_TIME		500 /* ms */
+#define DWELL_SAMPLE_INTERVAL	10
+
 /* Sideband registers and their sizes as defined in the USB4 spec */
 struct sb_reg {
 	unsigned int reg;
@@ -399,6 +408,9 @@ static ssize_t retimer_sb_regs_write(struct file *file,
  *					range (in mV).
  * @time_steps: Number of time margin steps
  * @max_time_offset: Maximum time margin offset (in mUI)
+ * @voltage_time_offset: Offset for voltage / time for software margining
+ * @dwell_time: Dwell time for software margining (in ms)
+ * @error_counter: Error counter operation for software margining
  * @optional_voltage_offset_range: Enable optional extended voltage range
  * @software: %true if software margining is used instead of hardware
  * @time: %true if time margining is used instead of voltage
@@ -422,12 +434,33 @@ struct tb_margining {
 	unsigned int max_voltage_offset_optional_range;
 	unsigned int time_steps;
 	unsigned int max_time_offset;
+	unsigned int voltage_time_offset;
+	unsigned int dwell_time;
+	enum usb4_margin_sw_error_counter error_counter;
 	bool optional_voltage_offset_range;
 	bool software;
 	bool time;
 	bool right_high;
 };
 
+static int margining_modify_error_counter(struct tb_margining *margining,
+	u32 lanes, enum usb4_margin_sw_error_counter error_counter)
+{
+	struct usb4_port_margining_params params = { 0 };
+	struct tb_port *port = margining->port;
+	u32 result;
+
+	if (error_counter != USB4_MARGIN_SW_ERROR_COUNTER_CLEAR &&
+	    error_counter != USB4_MARGIN_SW_ERROR_COUNTER_STOP)
+		return -EOPNOTSUPP;
+
+	params.error_counter = error_counter;
+	params.lanes = lanes;
+
+	return usb4_port_sw_margin(port, margining->target, margining->index,
+				   &params, &result);
+}
+
 static bool supports_software(const struct tb_margining *margining)
 {
 	return margining->caps[0] & USB4_MARGIN_CAP_0_MODES_SW;
@@ -689,9 +722,165 @@ static int margining_lanes_show(struct seq_file *s, void *not_used)
 DEBUGFS_ATTR_RW(margining_lanes);
 
 static ssize_t
-margining_optional_voltage_offset_write(struct file *file,
-				   const char __user *user_buf,
-				   size_t count, loff_t *ppos)
+margining_voltage_time_offset_write(struct file *file,
+				    const char __user *user_buf,
+				    size_t count, loff_t *ppos)
+{
+	struct seq_file *s = file->private_data;
+	struct tb_margining *margining = s->private;
+	struct tb *tb = margining->port->sw->tb;
+	unsigned int max_margin;
+	unsigned int val;
+	int ret;
+
+	ret = kstrtouint_from_user(user_buf, count, 10, &val);
+	if (ret)
+		return ret;
+
+	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &tb->lock) {
+		if (!margining->software)
+			return -EOPNOTSUPP;
+
+		if (margining->time)
+			max_margin = margining->time_steps;
+		else
+			if (margining->optional_voltage_offset_range)
+				max_margin = margining->voltage_steps_optional_range;
+			else
+				max_margin = margining->voltage_steps;
+
+		margining->voltage_time_offset = clamp(val, 0, max_margin);
+	}
+
+	return count;
+}
+
+static int margining_voltage_time_offset_show(struct seq_file *s,
+					      void *not_used)
+{
+	const struct tb_margining *margining = s->private;
+	struct tb *tb = margining->port->sw->tb;
+
+	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &tb->lock) {
+		if (!margining->software)
+			return -EOPNOTSUPP;
+
+		seq_printf(s, "%d\n", margining->voltage_time_offset);
+	}
+
+	return 0;
+}
+DEBUGFS_ATTR_RW(margining_voltage_time_offset);
+
+static ssize_t
+margining_error_counter_write(struct file *file, const char __user *user_buf,
+			      size_t count, loff_t *ppos)
+{
+	enum usb4_margin_sw_error_counter error_counter;
+	struct seq_file *s = file->private_data;
+	struct tb_margining *margining = s->private;
+	struct tb *tb = margining->port->sw->tb;
+	char *buf;
+
+	buf = validate_and_copy_from_user(user_buf, &count);
+	if (IS_ERR(buf))
+		return PTR_ERR(buf);
+
+	buf[count - 1] = '\0';
+
+	if (!strcmp(buf, "nop"))
+		error_counter = USB4_MARGIN_SW_ERROR_COUNTER_NOP;
+	else if (!strcmp(buf, "clear"))
+		error_counter = USB4_MARGIN_SW_ERROR_COUNTER_CLEAR;
+	else if (!strcmp(buf, "start"))
+		error_counter = USB4_MARGIN_SW_ERROR_COUNTER_START;
+	else if (!strcmp(buf, "stop"))
+		error_counter = USB4_MARGIN_SW_ERROR_COUNTER_STOP;
+	else
+		return -EINVAL;
+
+	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &tb->lock) {
+		if (!margining->software)
+			return -EOPNOTSUPP;
+
+		margining->error_counter = error_counter;
+	}
+
+	return count;
+}
+
+static int margining_error_counter_show(struct seq_file *s, void *not_used)
+{
+	const struct tb_margining *margining = s->private;
+	struct tb *tb = margining->port->sw->tb;
+
+	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &tb->lock) {
+		if (!margining->software)
+			return -EOPNOTSUPP;
+
+		switch (margining->error_counter) {
+		case USB4_MARGIN_SW_ERROR_COUNTER_NOP:
+			seq_puts(s, "[nop] clear start stop\n");
+			break;
+		case USB4_MARGIN_SW_ERROR_COUNTER_CLEAR:
+			seq_puts(s, "nop [clear] start stop\n");
+			break;
+		case USB4_MARGIN_SW_ERROR_COUNTER_START:
+			seq_puts(s, "nop clear [start] stop\n");
+			break;
+		case USB4_MARGIN_SW_ERROR_COUNTER_STOP:
+			seq_puts(s, "nop clear start [stop]\n");
+			break;
+		}
+	}
+
+	return 0;
+}
+DEBUGFS_ATTR_RW(margining_error_counter);
+
+static ssize_t
+margining_dwell_time_write(struct file *file, const char __user *user_buf,
+			   size_t count, loff_t *ppos)
+{
+	struct seq_file *s = file->private_data;
+	struct tb_margining *margining = s->private;
+	struct tb *tb = margining->port->sw->tb;
+	unsigned int val;
+	int ret;
+
+	ret = kstrtouint_from_user(user_buf, count, 10, &val);
+	if (ret)
+		return ret;
+
+	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &tb->lock) {
+		if (!margining->software)
+			return -EOPNOTSUPP;
+
+		margining->dwell_time = clamp(val, MIN_DWELL_TIME, MAX_DWELL_TIME);
+	}
+
+	return count;
+}
+
+static int margining_dwell_time_show(struct seq_file *s, void *not_used)
+{
+	struct tb_margining *margining = s->private;
+	struct tb *tb = margining->port->sw->tb;
+
+	scoped_cond_guard(mutex_intr, return -ERESTARTSYS, &tb->lock) {
+		if (!margining->software)
+			return -EOPNOTSUPP;
+
+		seq_printf(s, "%d\n", margining->dwell_time);
+	}
+
+	return 0;
+}
+DEBUGFS_ATTR_RW(margining_dwell_time);
+
+static ssize_t
+margining_optional_voltage_offset_write(struct file *file, const char __user *user_buf,
+					size_t count, loff_t *ppos)
 {
 	struct seq_file *s = file->private_data;
 	struct tb_margining *margining = s->private;
@@ -796,6 +985,50 @@ static int margining_mode_show(struct seq_file *s, void *not_used)
 }
 DEBUGFS_ATTR_RW(margining_mode);
 
+static int margining_run_sw(struct tb_margining *margining,
+			    struct usb4_port_margining_params *params)
+{
+	u32 nsamples = margining->dwell_time / DWELL_SAMPLE_INTERVAL;
+	u32 errors;
+	int ret, i;
+
+	ret = usb4_port_sw_margin(margining->port, margining->target, margining->index,
+				  params, margining->results);
+	if (ret)
+		goto out_stop;
+
+	for (i = 0; i <= nsamples; i++) {
+		ret = usb4_port_sw_margin_errors(margining->port, margining->target,
+						 margining->index, &margining->results[1]);
+		if (ret)
+			break;
+
+		if (margining->lanes == USB4_MARGIN_SW_LANE_0)
+			errors = FIELD_GET(USB4_MARGIN_SW_ERR_COUNTER_LANE_0_MASK,
+					   margining->results[1]);
+		else if (margining->lanes == USB4_MARGIN_SW_LANE_1)
+			errors = FIELD_GET(USB4_MARGIN_SW_ERR_COUNTER_LANE_1_MASK,
+					   margining->results[1]);
+		else if (margining->lanes == USB4_MARGIN_SW_ALL_LANES)
+			errors = margining->results[1];
+
+		/* Any errors stop the test */
+		if (errors)
+			break;
+
+		fsleep(DWELL_SAMPLE_INTERVAL * USEC_PER_MSEC);
+	}
+
+out_stop:
+	/*
+	 * Stop the counters but don't clear them to allow the
+	 * different error counter configurations.
+	 */
+	margining_modify_error_counter(margining, margining->lanes,
+				       USB4_MARGIN_SW_ERROR_COUNTER_STOP);
+	return ret;
+}
+
 static int margining_run_write(void *data, u64 val)
 {
 	struct tb_margining *margining = data;
@@ -836,11 +1069,15 @@ static int margining_run_write(void *data, u64 val)
 		clx = ret;
 	}
 
+	/* Clear the results */
+	memset(margining->results, 0, sizeof(margining->results));
+
 	if (margining->software) {
 		struct usb4_port_margining_params params = {
 			.error_counter = USB4_MARGIN_SW_ERROR_COUNTER_CLEAR,
 			.lanes = margining->lanes,
 			.time = margining->time,
+			.voltage_time_offset = margining->voltage_time_offset,
 			.right_high = margining->right_high,
 			.optional_voltage_offset_range = margining->optional_voltage_offset_range,
 		};
@@ -850,14 +1087,7 @@ static int margining_run_write(void *data, u64 val)
 			    margining->time ? "time" : "voltage", dev_name(dev),
 			    margining->lanes);
 
-		ret = usb4_port_sw_margin(port, margining->target, margining->index, &params,
-					  &margining->results[0]);
-		if (ret)
-			goto out_clx;
-
-		ret = usb4_port_sw_margin_errors(port, margining->target,
-						 margining->index,
-						 &margining->results[0]);
+		ret = margining_run_sw(margining, &params);
 	} else {
 		struct usb4_port_margining_params params = {
 			.ber_level = margining->ber_level,
@@ -867,10 +1097,6 @@ static int margining_run_write(void *data, u64 val)
 			.optional_voltage_offset_range = margining->optional_voltage_offset_range,
 		};
 
-		/* Clear the results */
-		margining->results[0] = 0;
-		margining->results[1] = 0;
-
 		tb_port_dbg(port,
 			    "running hardware %s lane margining for %s lanes %u\n",
 			    margining->time ? "time" : "voltage", dev_name(dev),
@@ -880,7 +1106,6 @@ static int margining_run_write(void *data, u64 val)
 					  margining->results);
 	}
 
-out_clx:
 	if (down_sw)
 		tb_switch_clx_enable(down_sw, clx);
 out_unlock:
@@ -909,6 +1134,13 @@ static ssize_t margining_results_write(struct file *file,
 	margining->results[0] = 0;
 	margining->results[1] = 0;
 
+	if (margining->software) {
+		/* Clear the error counters */
+		margining_modify_error_counter(margining,
+					       USB4_MARGIN_SW_ALL_LANES,
+					       USB4_MARGIN_SW_ERROR_COUNTER_CLEAR);
+	}
+
 	mutex_unlock(&tb->lock);
 	return count;
 }
@@ -998,6 +1230,24 @@ static int margining_results_show(struct seq_file *s, void *not_used)
 				voltage_margin_show(s, margining, val);
 			}
 		}
+	} else {
+		u32 lane_errors, result;
+
+		seq_printf(s, "0x%08x\n", margining->results[1]);
+		result = FIELD_GET(USB4_MARGIN_SW_LANES_MASK, margining->results[0]);
+
+		if (result == USB4_MARGIN_SW_LANE_0 ||
+		    result == USB4_MARGIN_SW_ALL_LANES) {
+			lane_errors = FIELD_GET(USB4_MARGIN_SW_ERR_COUNTER_LANE_0_MASK,
+						margining->results[1]);
+			seq_printf(s, "# lane 0 errors: %u\n", lane_errors);
+		}
+		if (result == USB4_MARGIN_SW_LANE_1 ||
+		    result == USB4_MARGIN_SW_ALL_LANES) {
+			lane_errors = FIELD_GET(USB4_MARGIN_SW_ERR_COUNTER_LANE_1_MASK,
+						margining->results[1]);
+			seq_printf(s, "# lane 1 errors: %u\n", lane_errors);
+		}
 	}
 
 	mutex_unlock(&tb->lock);
@@ -1211,9 +1461,21 @@ static struct tb_margining *margining_alloc(struct tb_port *port,
 		debugfs_create_file("margin", 0600, dir, margining,
 				    &margining_margin_fops);
 
+	margining->error_counter = USB4_MARGIN_SW_ERROR_COUNTER_CLEAR;
+	margining->dwell_time = MIN_DWELL_TIME;
+
 	if (supports_optional_voltage_offset_range(margining))
 		debugfs_create_file("optional_voltage_offset", DEBUGFS_MODE, dir, margining,
 				    &margining_optional_voltage_offset_fops);
+
+	if (supports_software(margining)) {
+		debugfs_create_file("voltage_time_offset", DEBUGFS_MODE, dir, margining,
+				    &margining_voltage_time_offset_fops);
+		debugfs_create_file("error_counter", DEBUGFS_MODE, dir, margining,
+				    &margining_error_counter_fops);
+		debugfs_create_file("dwell_time", DEBUGFS_MODE, dir, margining,
+				    &margining_dwell_time_fops);
+	}
 	return margining;
 }
 
diff --git a/drivers/thunderbolt/sb_regs.h b/drivers/thunderbolt/sb_regs.h
index 8bff0740222c..dbcad25ead50 100644
--- a/drivers/thunderbolt/sb_regs.h
+++ b/drivers/thunderbolt/sb_regs.h
@@ -86,9 +86,17 @@ enum usb4_sb_opcode {
 #define USB4_MARGIN_HW_RES_1_L1_LL_MARGIN_SHIFT	24
 
 /* USB4_SB_OPCODE_RUN_SW_LANE_MARGINING */
+#define USB4_MARGIN_SW_LANES_MASK		GENMASK(2, 0)
+#define USB4_MARGIN_SW_LANE_0			0x0
+#define USB4_MARGIN_SW_LANE_1			0x1
+#define USB4_MARGIN_SW_ALL_LANES		0x7
 #define USB4_MARGIN_SW_TIME			BIT(3)
 #define USB4_MARGIN_SW_RH			BIT(4)
 #define USB4_MARGIN_SW_OPT_VOLTAGE		BIT(5)
+#define USB4_MARGIN_SW_VT_MASK			GENMASK(12, 6)
 #define USB4_MARGIN_SW_COUNTER_MASK		GENMASK(14, 13)
 
+#define USB4_MARGIN_SW_ERR_COUNTER_LANE_0_MASK	GENMASK(3, 0)
+#define USB4_MARGIN_SW_ERR_COUNTER_LANE_1_MASK	GENMASK(7, 4)
+
 #endif
diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
index 262c333924b8..6737188f2581 100644
--- a/drivers/thunderbolt/tb.h
+++ b/drivers/thunderbolt/tb.h
@@ -1372,6 +1372,7 @@ enum usb4_margin_sw_error_counter {
  * @error_counter: Error counter operation for software margining
  * @ber_level: Current BER level contour value
  * @lanes: %0, %1 or %7 (all)
+ * @voltage_time_offset: Offset for voltage / time for software margining
  * @optional_voltage_offset_range: Enable optional extended voltage range
  * @right_high: %false if left/low margin test is performed, %true if right/high
  * @time: %true if time margining is used instead of voltage
@@ -1380,6 +1381,7 @@ struct usb4_port_margining_params {
 	enum usb4_margin_sw_error_counter error_counter;
 	u32 ber_level;
 	u32 lanes;
+	u32 voltage_time_offset;
 	bool optional_voltage_offset_range;
 	bool right_high;
 	bool time;
diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
index a2f81e17ad8d..0a9b4aeb3fa1 100644
--- a/drivers/thunderbolt/usb4.c
+++ b/drivers/thunderbolt/usb4.c
@@ -1723,6 +1723,7 @@ int usb4_port_sw_margin(struct tb_port *port, enum usb4_sb_target target,
 	if (params->right_high)
 		val |= USB4_MARGIN_SW_RH;
 	val |= FIELD_PREP(USB4_MARGIN_SW_COUNTER_MASK, params->error_counter);
+	val |= FIELD_PREP(USB4_MARGIN_SW_VT_MASK, params->voltage_time_offset);
 
 	ret = usb4_port_sb_write(port, target, index, USB4_SB_METADATA, &val,
 				 sizeof(val));
-- 
2.43.0

Re: [PATCH 4/4] thunderbolt: Improve software receiver lane margining

[Dan Carpenter]

Hi Mika,

kernel test robot noticed the following build warnings:

https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Mika-Westerberg/thunderbolt-Add-missing-usb4_port_sb_read-to-usb4_port_sw_margin/20240815-001205
base:   https://git.kernel.org/pub/scm/linux/kernel/git/westeri/thunderbolt.git next
patch link:    https://lore.kernel.org/r/20240813110135.2178900-5-mika.westerberg%40linux.intel.com
patch subject: [PATCH 4/4] thunderbolt: Improve software receiver lane margining
config: i386-randconfig-141-20240815 (https://download.01.org/0day-ci/archive/20240816/202408161041.jjzazHm4-lkp@intel.com/config)
compiler: gcc-12 (Debian 12.2.0-14) 12.2.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202408161041.jjzazHm4-lkp@intel.com/

smatch warnings:
drivers/thunderbolt/debugfs.c:1014 margining_run_sw() error: uninitialized symbol 'errors'.

vim +/errors +1014 drivers/thunderbolt/debugfs.c

c0188291a5471b R Kannappan     2024-08-13   986  static int margining_run_sw(struct tb_margining *margining,
c0188291a5471b R Kannappan     2024-08-13   987  			    struct usb4_port_margining_params *params)
c0188291a5471b R Kannappan     2024-08-13   988  {
c0188291a5471b R Kannappan     2024-08-13   989  	u32 nsamples = margining->dwell_time / DWELL_SAMPLE_INTERVAL;
c0188291a5471b R Kannappan     2024-08-13   990  	u32 errors;
c0188291a5471b R Kannappan     2024-08-13   991  	int ret, i;
c0188291a5471b R Kannappan     2024-08-13   992  
c0188291a5471b R Kannappan     2024-08-13   993  	ret = usb4_port_sw_margin(margining->port, margining->target, margining->index,
c0188291a5471b R Kannappan     2024-08-13   994  				  params, margining->results);
c0188291a5471b R Kannappan     2024-08-13   995  	if (ret)
c0188291a5471b R Kannappan     2024-08-13   996  		goto out_stop;
c0188291a5471b R Kannappan     2024-08-13   997  
c0188291a5471b R Kannappan     2024-08-13   998  	for (i = 0; i <= nsamples; i++) {
c0188291a5471b R Kannappan     2024-08-13   999  		ret = usb4_port_sw_margin_errors(margining->port, margining->target,
c0188291a5471b R Kannappan     2024-08-13  1000  						 margining->index, &margining->results[1]);
c0188291a5471b R Kannappan     2024-08-13  1001  		if (ret)
c0188291a5471b R Kannappan     2024-08-13  1002  			break;
c0188291a5471b R Kannappan     2024-08-13  1003  
c0188291a5471b R Kannappan     2024-08-13  1004  		if (margining->lanes == USB4_MARGIN_SW_LANE_0)
c0188291a5471b R Kannappan     2024-08-13  1005  			errors = FIELD_GET(USB4_MARGIN_SW_ERR_COUNTER_LANE_0_MASK,
c0188291a5471b R Kannappan     2024-08-13  1006  					   margining->results[1]);
c0188291a5471b R Kannappan     2024-08-13  1007  		else if (margining->lanes == USB4_MARGIN_SW_LANE_1)
c0188291a5471b R Kannappan     2024-08-13  1008  			errors = FIELD_GET(USB4_MARGIN_SW_ERR_COUNTER_LANE_1_MASK,
c0188291a5471b R Kannappan     2024-08-13  1009  					   margining->results[1]);
c0188291a5471b R Kannappan     2024-08-13  1010  		else if (margining->lanes == USB4_MARGIN_SW_ALL_LANES)
c0188291a5471b R Kannappan     2024-08-13  1011  			errors = margining->results[1];

The static checker wants an else statement.

c0188291a5471b R Kannappan     2024-08-13  1012  
c0188291a5471b R Kannappan     2024-08-13  1013  		/* Any errors stop the test */
c0188291a5471b R Kannappan     2024-08-13 @1014  		if (errors)
c0188291a5471b R Kannappan     2024-08-13  1015  			break;
c0188291a5471b R Kannappan     2024-08-13  1016  
c0188291a5471b R Kannappan     2024-08-13  1017  		fsleep(DWELL_SAMPLE_INTERVAL * USEC_PER_MSEC);
c0188291a5471b R Kannappan     2024-08-13  1018  	}
c0188291a5471b R Kannappan     2024-08-13  1019  
c0188291a5471b R Kannappan     2024-08-13  1020  out_stop:
c0188291a5471b R Kannappan     2024-08-13  1021  	/*
c0188291a5471b R Kannappan     2024-08-13  1022  	 * Stop the counters but don't clear them to allow the
c0188291a5471b R Kannappan     2024-08-13  1023  	 * different error counter configurations.
c0188291a5471b R Kannappan     2024-08-13  1024  	 */
c0188291a5471b R Kannappan     2024-08-13  1025  	margining_modify_error_counter(margining, margining->lanes,
c0188291a5471b R Kannappan     2024-08-13  1026  				       USB4_MARGIN_SW_ERROR_COUNTER_STOP);
c0188291a5471b R Kannappan     2024-08-13  1027  	return ret;
c0188291a5471b R Kannappan     2024-08-13  1028  }

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki