diff --git a/Documentation/ABI/testing/sysfs-bus-intel_th-output-devices b/Documentation/ABI/testing/sysfs-bus-intel_th-output-devices
index 4d48a9451866..d1f667104944 100644
--- a/Documentation/ABI/testing/sysfs-bus-intel_th-output-devices
+++ b/Documentation/ABI/testing/sysfs-bus-intel_th-output-devices
@@ -3,11 +3,13 @@ Date:		June 2015
 KernelVersion:	4.3
 Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
 Description:	(RW) Writes of 1 or 0 enable or disable trace output to this
-		output device. Reads return current status.
+		output device. Reads return current status. Requires that the
+		correstponding output port driver be loaded.
 
 What:		/sys/bus/intel_th/devices/<intel_th_id>-msc<msc-id>/port
 Date:		June 2015
 KernelVersion:	4.3
 Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>
 Description:	(RO) Port number, corresponding to this output device on the
-		switch (GTH).
+		switch (GTH) or "unassigned" if the corresponding output
+		port driver is not loaded.
diff --git a/drivers/hwtracing/intel_th/core.c b/drivers/hwtracing/intel_th/core.c
index fc6b7f8b62fb..7c1acc2f801c 100644
--- a/drivers/hwtracing/intel_th/core.c
+++ b/drivers/hwtracing/intel_th/core.c
@@ -422,6 +422,7 @@ static const struct intel_th_subdevice {
 	unsigned		nres;
 	unsigned		type;
 	unsigned		otype;
+	bool			mknode;
 	unsigned		scrpd;
 	int			id;
 } intel_th_subdevices[] = {
@@ -456,6 +457,7 @@ static const struct intel_th_subdevice {
 		.name	= "msc",
 		.id	= 0,
 		.type	= INTEL_TH_OUTPUT,
+		.mknode	= true,
 		.otype	= GTH_MSU,
 		.scrpd	= SCRPD_MEM_IS_PRIM_DEST | SCRPD_MSC0_IS_ENABLED,
 	},
@@ -476,6 +478,7 @@ static const struct intel_th_subdevice {
 		.name	= "msc",
 		.id	= 1,
 		.type	= INTEL_TH_OUTPUT,
+		.mknode	= true,
 		.otype	= GTH_MSU,
 		.scrpd	= SCRPD_MEM_IS_PRIM_DEST | SCRPD_MSC1_IS_ENABLED,
 	},
@@ -635,7 +638,8 @@ intel_th_subdevice_alloc(struct intel_th *th,
 	}
 
 	if (subdev->type == INTEL_TH_OUTPUT) {
-		thdev->dev.devt = MKDEV(th->major, th->num_thdevs);
+		if (subdev->mknode)
+			thdev->dev.devt = MKDEV(th->major, th->num_thdevs);
 		thdev->output.type = subdev->otype;
 		thdev->output.port = -1;
 		thdev->output.scratchpad = subdev->scrpd;
diff --git a/drivers/hwtracing/intel_th/gth.c b/drivers/hwtracing/intel_th/gth.c
index 8426b7970c14..cc287cf6eb29 100644
--- a/drivers/hwtracing/intel_th/gth.c
+++ b/drivers/hwtracing/intel_th/gth.c
@@ -607,6 +607,7 @@ static void intel_th_gth_unassign(struct intel_th_device *thdev,
 {
 	struct gth_device *gth = dev_get_drvdata(&thdev->dev);
 	int port = othdev->output.port;
+	int master;
 
 	if (thdev->host_mode)
 		return;
@@ -615,6 +616,9 @@ static void intel_th_gth_unassign(struct intel_th_device *thdev,
 	othdev->output.port = -1;
 	othdev->output.active = false;
 	gth->output[port].output = NULL;
+	for (master = 0; master < TH_CONFIGURABLE_MASTERS; master++)
+		if (gth->master[master] == port)
+			gth->master[master] = -1;
 	spin_unlock(&gth->gth_lock);
 }
 
diff --git a/drivers/hwtracing/intel_th/pti.c b/drivers/hwtracing/intel_th/pti.c
index 56694339cb06..0da6b787f553 100644
--- a/drivers/hwtracing/intel_th/pti.c
+++ b/drivers/hwtracing/intel_th/pti.c
@@ -272,19 +272,17 @@ static ssize_t lpp_dest_store(struct device *dev, struct device_attribute *attr,
 			      const char *buf, size_t size)
 {
 	struct pti_device *pti = dev_get_drvdata(dev);
-	ssize_t ret = -EINVAL;
 	int i;
 
-	for (i = 0; i < ARRAY_SIZE(lpp_dest_str); i++)
-		if (sysfs_streq(buf, lpp_dest_str[i]))
-			break;
+	i = sysfs_match_string(lpp_dest_str, buf);
+	if (i < 0)
+		return i;
 
-	if (i < ARRAY_SIZE(lpp_dest_str) && pti->lpp_dest_mask & BIT(i)) {
-		pti->lpp_dest = i;
-		ret = size;
-	}
+	if (!(pti->lpp_dest_mask & BIT(i)))
+		return -EINVAL;
 
-	return ret;
+	pti->lpp_dest = i;
+	return size;
 }
 
 static DEVICE_ATTR_RW(lpp_dest);
diff --git a/drivers/hwtracing/intel_th/sth.c b/drivers/hwtracing/intel_th/sth.c
index 4b7ae47789d2..3a1f4e650378 100644
--- a/drivers/hwtracing/intel_th/sth.c
+++ b/drivers/hwtracing/intel_th/sth.c
@@ -84,8 +84,12 @@ static ssize_t notrace sth_stm_packet(struct stm_data *stm_data,
 	/* Global packets (GERR, XSYNC, TRIG) are sent with register writes */
 	case STP_PACKET_GERR:
 		reg += 4;
+		/* fall through */
+
 	case STP_PACKET_XSYNC:
 		reg += 8;
+		/* fall through */
+
 	case STP_PACKET_TRIG:
 		if (flags & STP_PACKET_TIMESTAMPED)
 			reg += 4;
diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 93ce3aa740a9..c7ba8acfd4d5 100644
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -244,6 +244,9 @@ static int find_free_channels(unsigned long *bitmap, unsigned int start,
 			;
 		if (i == width)
 			return pos;
+
+		/* step over [pos..pos+i) to continue search */
+		pos += i;
 	}
 
 	return -1;
@@ -732,7 +735,7 @@ static int stm_char_policy_set_ioctl(struct stm_file *stmf, void __user *arg)
 	struct stm_device *stm = stmf->stm;
 	struct stp_policy_id *id;
 	char *ids[] = { NULL, NULL };
-	int ret = -EINVAL;
+	int ret = -EINVAL, wlimit = 1;
 	u32 size;
 
 	if (stmf->output.nr_chans)
@@ -760,8 +763,10 @@ static int stm_char_policy_set_ioctl(struct stm_file *stmf, void __user *arg)
 	if (id->__reserved_0 || id->__reserved_1)
 		goto err_free;
 
-	if (id->width < 1 ||
-	    id->width > PAGE_SIZE / stm->data->sw_mmiosz)
+	if (stm->data->sw_mmiosz)
+		wlimit = PAGE_SIZE / stm->data->sw_mmiosz;
+
+	if (id->width < 1 || id->width > wlimit)
 		goto err_free;
 
 	ids[0] = id->id;