Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

1 files changed, 494 insertions, 0 deletions

diff --git a/sound/usb/implicit.c b/sound/usb/implicit.c
new file mode 100644
index 000000000..77f06da93
--- /dev/null
+++ b/sound/usb/implicit.c
@@ -0,0 +1,494 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+//
+// Special handling for implicit feedback mode
+//
+
+#include <linux/init.h>
+#include <linux/usb.h>
+#include <linux/usb/audio.h>
+#include <linux/usb/audio-v2.h>
+
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+
+#include "usbaudio.h"
+#include "card.h"
+#include "helper.h"
+#include "pcm.h"
+#include "implicit.h"
+
+enum {
+	IMPLICIT_FB_NONE,
+	IMPLICIT_FB_GENERIC,
+	IMPLICIT_FB_FIXED,
+	IMPLICIT_FB_BOTH,	/* generic playback + capture (for BOSS) */
+};
+
+struct snd_usb_implicit_fb_match {
+	unsigned int id;
+	unsigned int iface_class;
+	unsigned int ep_num;
+	unsigned int iface;
+	int type;
+};
+
+#define IMPLICIT_FB_GENERIC_DEV(vend, prod) \
+	{ .id = USB_ID(vend, prod), .type = IMPLICIT_FB_GENERIC }
+#define IMPLICIT_FB_FIXED_DEV(vend, prod, ep, ifnum) \
+	{ .id = USB_ID(vend, prod), .type = IMPLICIT_FB_FIXED, .ep_num = (ep),\
+	    .iface = (ifnum) }
+#define IMPLICIT_FB_BOTH_DEV(vend, prod, ep, ifnum) \
+	{ .id = USB_ID(vend, prod), .type = IMPLICIT_FB_BOTH, .ep_num = (ep),\
+	    .iface = (ifnum) }
+#define IMPLICIT_FB_SKIP_DEV(vend, prod) \
+	{ .id = USB_ID(vend, prod), .type = IMPLICIT_FB_NONE }
+
+/* Implicit feedback quirk table for playback */
+static const struct snd_usb_implicit_fb_match playback_implicit_fb_quirks[] = {
+	/* Fixed EP */
+	/* FIXME: check the availability of generic matching */
+	IMPLICIT_FB_FIXED_DEV(0x0763, 0x2030, 0x81, 3), /* M-Audio Fast Track C400 */
+	IMPLICIT_FB_FIXED_DEV(0x0763, 0x2031, 0x81, 3), /* M-Audio Fast Track C600 */
+	IMPLICIT_FB_FIXED_DEV(0x0763, 0x2080, 0x81, 2), /* M-Audio FastTrack Ultra */
+	IMPLICIT_FB_FIXED_DEV(0x0763, 0x2081, 0x81, 2), /* M-Audio FastTrack Ultra */
+	IMPLICIT_FB_FIXED_DEV(0x2466, 0x8010, 0x81, 2), /* Fractal Audio Axe-Fx III */
+	IMPLICIT_FB_FIXED_DEV(0x31e9, 0x0001, 0x81, 2), /* Solid State Logic SSL2 */
+	IMPLICIT_FB_FIXED_DEV(0x31e9, 0x0002, 0x81, 2), /* Solid State Logic SSL2+ */
+	IMPLICIT_FB_FIXED_DEV(0x0499, 0x172f, 0x81, 2), /* Steinberg UR22C */
+	IMPLICIT_FB_FIXED_DEV(0x0d9a, 0x00df, 0x81, 2), /* RTX6001 */
+	IMPLICIT_FB_FIXED_DEV(0x19f7, 0x000a, 0x84, 3), /* RODE AI-1 */
+	IMPLICIT_FB_FIXED_DEV(0x22f0, 0x0006, 0x81, 3), /* Allen&Heath Qu-16 */
+	IMPLICIT_FB_FIXED_DEV(0x1686, 0xf029, 0x82, 2), /* Zoom UAC-2 */
+	IMPLICIT_FB_FIXED_DEV(0x2466, 0x8003, 0x86, 2), /* Fractal Audio Axe-Fx II */
+	IMPLICIT_FB_FIXED_DEV(0x0499, 0x172a, 0x86, 2), /* Yamaha MODX */
+
+	/* Special matching */
+	{ .id = USB_ID(0x07fd, 0x0004), .iface_class = USB_CLASS_AUDIO,
+	  .type = IMPLICIT_FB_NONE },		/* MicroBook IIc */
+	/* ep = 0x84, ifnum = 0 */
+	{ .id = USB_ID(0x07fd, 0x0004), .iface_class = USB_CLASS_VENDOR_SPEC,
+	  .type = IMPLICIT_FB_FIXED,
+	  .ep_num = 0x84, .iface = 0 },		/* MOTU MicroBook II */
+
+	{} /* terminator */
+};
+
+/* Implicit feedback quirk table for capture: only FIXED type */
+static const struct snd_usb_implicit_fb_match capture_implicit_fb_quirks[] = {
+	{} /* terminator */
+};
+
+/* set up sync EP information on the audioformat */
+static int add_implicit_fb_sync_ep(struct snd_usb_audio *chip,
+				   struct audioformat *fmt,
+				   int ep, int ep_idx, int ifnum,
+				   const struct usb_host_interface *alts)
+{
+	struct usb_interface *iface;
+
+	if (!alts) {
+		iface = usb_ifnum_to_if(chip->dev, ifnum);
+		if (!iface || iface->num_altsetting < 2)
+			return 0;
+		alts = &iface->altsetting[1];
+	}
+
+	fmt->sync_ep = ep;
+	fmt->sync_iface = ifnum;
+	fmt->sync_altsetting = alts->desc.bAlternateSetting;
+	fmt->sync_ep_idx = ep_idx;
+	fmt->implicit_fb = 1;
+	usb_audio_dbg(chip,
+		      "%d:%d: added %s implicit_fb sync_ep %x, iface %d:%d\n",
+		      fmt->iface, fmt->altsetting,
+		      (ep & USB_DIR_IN) ? "playback" : "capture",
+		      fmt->sync_ep, fmt->sync_iface, fmt->sync_altsetting);
+	return 1;
+}
+
+/* Check whether the given UAC2 iface:altset points to an implicit fb source */
+static int add_generic_uac2_implicit_fb(struct snd_usb_audio *chip,
+					struct audioformat *fmt,
+					unsigned int ifnum,
+					unsigned int altsetting)
+{
+	struct usb_host_interface *alts;
+	struct usb_endpoint_descriptor *epd;
+
+	alts = snd_usb_get_host_interface(chip, ifnum, altsetting);
+	if (!alts)
+		return 0;
+	if (alts->desc.bInterfaceClass != USB_CLASS_AUDIO ||
+	    alts->desc.bInterfaceSubClass != USB_SUBCLASS_AUDIOSTREAMING ||
+	    alts->desc.bInterfaceProtocol != UAC_VERSION_2 ||
+	    alts->desc.bNumEndpoints < 1)
+		return 0;
+	epd = get_endpoint(alts, 0);
+	if (!usb_endpoint_is_isoc_in(epd) ||
+	    (epd->bmAttributes & USB_ENDPOINT_USAGE_MASK) !=
+					USB_ENDPOINT_USAGE_IMPLICIT_FB)
+		return 0;
+	return add_implicit_fb_sync_ep(chip, fmt, epd->bEndpointAddress, 0,
+				       ifnum, alts);
+}
+
+static bool roland_sanity_check_iface(struct usb_host_interface *alts)
+{
+	if (alts->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC ||
+	    (alts->desc.bInterfaceSubClass != 2 &&
+	     alts->desc.bInterfaceProtocol != 2) ||
+	    alts->desc.bNumEndpoints < 1)
+		return false;
+	return true;
+}
+
+/* Like the UAC2 case above, but specific to Roland with vendor class and hack */
+static int add_roland_implicit_fb(struct snd_usb_audio *chip,
+				  struct audioformat *fmt,
+				  struct usb_host_interface *alts)
+{
+	struct usb_endpoint_descriptor *epd;
+
+	if (!roland_sanity_check_iface(alts))
+		return 0;
+	/* only when both streams are with ASYNC type */
+	epd = get_endpoint(alts, 0);
+	if (!usb_endpoint_is_isoc_out(epd) ||
+	    (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC)
+		return 0;
+
+	/* check capture EP */
+	alts = snd_usb_get_host_interface(chip,
+					  alts->desc.bInterfaceNumber + 1,
+					  alts->desc.bAlternateSetting);
+	if (!alts || !roland_sanity_check_iface(alts))
+		return 0;
+	epd = get_endpoint(alts, 0);
+	if (!usb_endpoint_is_isoc_in(epd) ||
+	    (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC)
+		return 0;
+	chip->quirk_flags |= QUIRK_FLAG_PLAYBACK_FIRST;
+	return add_implicit_fb_sync_ep(chip, fmt, epd->bEndpointAddress, 0,
+				       alts->desc.bInterfaceNumber, alts);
+}
+
+/* capture quirk for Roland device; always full-duplex */
+static int add_roland_capture_quirk(struct snd_usb_audio *chip,
+				    struct audioformat *fmt,
+				    struct usb_host_interface *alts)
+{
+	struct usb_endpoint_descriptor *epd;
+
+	if (!roland_sanity_check_iface(alts))
+		return 0;
+	epd = get_endpoint(alts, 0);
+	if (!usb_endpoint_is_isoc_in(epd) ||
+	    (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC)
+		return 0;
+
+	alts = snd_usb_get_host_interface(chip,
+					  alts->desc.bInterfaceNumber - 1,
+					  alts->desc.bAlternateSetting);
+	if (!alts || !roland_sanity_check_iface(alts))
+		return 0;
+	epd = get_endpoint(alts, 0);
+	if (!usb_endpoint_is_isoc_out(epd))
+		return 0;
+	return add_implicit_fb_sync_ep(chip, fmt, epd->bEndpointAddress, 0,
+				       alts->desc.bInterfaceNumber, alts);
+}
+
+/* Playback and capture EPs on Pioneer devices share the same iface/altset
+ * for the implicit feedback operation
+ */
+static bool is_pioneer_implicit_fb(struct snd_usb_audio *chip,
+				   struct usb_host_interface *alts)
+
+{
+	struct usb_endpoint_descriptor *epd;
+
+	if (USB_ID_VENDOR(chip->usb_id) != 0x2b73 &&
+	    USB_ID_VENDOR(chip->usb_id) != 0x08e4)
+		return false;
+	if (alts->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC)
+		return false;
+	if (alts->desc.bNumEndpoints != 2)
+		return false;
+
+	epd = get_endpoint(alts, 0);
+	if (!usb_endpoint_is_isoc_out(epd) ||
+	    (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC)
+		return false;
+
+	epd = get_endpoint(alts, 1);
+	if (!usb_endpoint_is_isoc_in(epd) ||
+	    (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC ||
+	    ((epd->bmAttributes & USB_ENDPOINT_USAGE_MASK) !=
+	     USB_ENDPOINT_USAGE_DATA &&
+	     (epd->bmAttributes & USB_ENDPOINT_USAGE_MASK) !=
+	     USB_ENDPOINT_USAGE_IMPLICIT_FB))
+		return false;
+
+	return true;
+}
+
+static int __add_generic_implicit_fb(struct snd_usb_audio *chip,
+				     struct audioformat *fmt,
+				     int iface, int altset)
+{
+	struct usb_host_interface *alts;
+	struct usb_endpoint_descriptor *epd;
+
+	alts = snd_usb_get_host_interface(chip, iface, altset);
+	if (!alts)
+		return 0;
+
+	if ((alts->desc.bInterfaceClass != USB_CLASS_VENDOR_SPEC &&
+	     alts->desc.bInterfaceClass != USB_CLASS_AUDIO) ||
+	    alts->desc.bNumEndpoints < 1)
+		return 0;
+	epd = get_endpoint(alts, 0);
+	if (!usb_endpoint_is_isoc_in(epd) ||
+	    (epd->bmAttributes & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC)
+		return 0;
+	return add_implicit_fb_sync_ep(chip, fmt, epd->bEndpointAddress, 0,
+				       iface, alts);
+}
+
+/* More generic quirk: look for the sync EP next to the data EP */
+static int add_generic_implicit_fb(struct snd_usb_audio *chip,
+				   struct audioformat *fmt,
+				   struct usb_host_interface *alts)
+{
+	if ((fmt->ep_attr & USB_ENDPOINT_SYNCTYPE) != USB_ENDPOINT_SYNC_ASYNC)
+		return 0;
+
+	if (__add_generic_implicit_fb(chip, fmt,
+				      alts->desc.bInterfaceNumber + 1,
+				      alts->desc.bAlternateSetting))
+		return 1;
+	return __add_generic_implicit_fb(chip, fmt,
+					 alts->desc.bInterfaceNumber - 1,
+					 alts->desc.bAlternateSetting);
+}
+
+static const struct snd_usb_implicit_fb_match *
+find_implicit_fb_entry(struct snd_usb_audio *chip,
+		       const struct snd_usb_implicit_fb_match *match,
+		       const struct usb_host_interface *alts)
+{
+	for (; match->id; match++)
+		if (match->id == chip->usb_id &&
+		    (!match->iface_class ||
+		     (alts->desc.bInterfaceClass == match->iface_class)))
+			return match;
+
+	return NULL;
+}
+
+/* Setup an implicit feedback endpoint from a quirk. Returns 0 if no quirk
+ * applies. Returns 1 if a quirk was found.
+ */
+static int audioformat_implicit_fb_quirk(struct snd_usb_audio *chip,
+					 struct audioformat *fmt,
+					 struct usb_host_interface *alts)
+{
+	const struct snd_usb_implicit_fb_match *p;
+	unsigned int attr = fmt->ep_attr & USB_ENDPOINT_SYNCTYPE;
+
+	p = find_implicit_fb_entry(chip, playback_implicit_fb_quirks, alts);
+	if (p) {
+		switch (p->type) {
+		case IMPLICIT_FB_GENERIC:
+			return add_generic_implicit_fb(chip, fmt, alts);
+		case IMPLICIT_FB_NONE:
+			return 0; /* No quirk */
+		case IMPLICIT_FB_FIXED:
+			return add_implicit_fb_sync_ep(chip, fmt, p->ep_num, 0,
+						       p->iface, NULL);
+		}
+	}
+
+	/* Special handling for devices with capture quirks */
+	p = find_implicit_fb_entry(chip, capture_implicit_fb_quirks, alts);
+	if (p) {
+		switch (p->type) {
+		case IMPLICIT_FB_FIXED:
+			return 0; /* no quirk */
+		case IMPLICIT_FB_BOTH:
+			chip->quirk_flags |= QUIRK_FLAG_PLAYBACK_FIRST;
+			return add_generic_implicit_fb(chip, fmt, alts);
+		}
+	}
+
+	/* Generic UAC2 implicit feedback */
+	if (attr == USB_ENDPOINT_SYNC_ASYNC &&
+	    alts->desc.bInterfaceClass == USB_CLASS_AUDIO &&
+	    alts->desc.bInterfaceProtocol == UAC_VERSION_2 &&
+	    alts->desc.bNumEndpoints == 1) {
+		if (add_generic_uac2_implicit_fb(chip, fmt,
+						 alts->desc.bInterfaceNumber + 1,
+						 alts->desc.bAlternateSetting))
+			return 1;
+	}
+
+	/* Roland/BOSS implicit feedback with vendor spec class */
+	if (USB_ID_VENDOR(chip->usb_id) == 0x0582) {
+		if (add_roland_implicit_fb(chip, fmt, alts) > 0)
+			return 1;
+	}
+
+	/* Pioneer devices with vendor spec class */
+	if (is_pioneer_implicit_fb(chip, alts)) {
+		chip->quirk_flags |= QUIRK_FLAG_PLAYBACK_FIRST;
+		return add_implicit_fb_sync_ep(chip, fmt,
+					       get_endpoint(alts, 1)->bEndpointAddress,
+					       1, alts->desc.bInterfaceNumber,
+					       alts);
+	}
+
+	/* Try the generic implicit fb if available */
+	if (chip->generic_implicit_fb ||
+	    (chip->quirk_flags & QUIRK_FLAG_GENERIC_IMPLICIT_FB))
+		return add_generic_implicit_fb(chip, fmt, alts);
+
+	/* No quirk */
+	return 0;
+}
+
+/* same for capture, but only handling FIXED entry */
+static int audioformat_capture_quirk(struct snd_usb_audio *chip,
+				     struct audioformat *fmt,
+				     struct usb_host_interface *alts)
+{
+	const struct snd_usb_implicit_fb_match *p;
+
+	p = find_implicit_fb_entry(chip, capture_implicit_fb_quirks, alts);
+	if (p && (p->type == IMPLICIT_FB_FIXED || p->type == IMPLICIT_FB_BOTH))
+		return add_implicit_fb_sync_ep(chip, fmt, p->ep_num, 0,
+					       p->iface, NULL);
+
+	/* Roland/BOSS need full-duplex streams */
+	if (USB_ID_VENDOR(chip->usb_id) == 0x0582) {
+		if (add_roland_capture_quirk(chip, fmt, alts) > 0)
+			return 1;
+	}
+
+	if (is_pioneer_implicit_fb(chip, alts))
+		return 1; /* skip the quirk, also don't handle generic sync EP */
+	return 0;
+}
+
+/*
+ * Parse altset and set up implicit feedback endpoint on the audioformat
+ */
+int snd_usb_parse_implicit_fb_quirk(struct snd_usb_audio *chip,
+				    struct audioformat *fmt,
+				    struct usb_host_interface *alts)
+{
+	if (chip->quirk_flags & QUIRK_FLAG_SKIP_IMPLICIT_FB)
+		return 0;
+	if (fmt->endpoint & USB_DIR_IN)
+		return audioformat_capture_quirk(chip, fmt, alts);
+	else
+		return audioformat_implicit_fb_quirk(chip, fmt, alts);
+}
+
+/*
+ * Return the score of matching two audioformats.
+ * Veto the audioformat if:
+ * - It has no channels for some reason.
+ * - Requested PCM format is not supported.
+ * - Requested sample rate is not supported.
+ */
+static int match_endpoint_audioformats(struct snd_usb_substream *subs,
+				       const struct audioformat *fp,
+				       int rate, int channels,
+				       snd_pcm_format_t pcm_format)
+{
+	int i, score;
+
+	if (fp->channels < 1)
+		return 0;
+
+	if (!(fp->formats & pcm_format_to_bits(pcm_format)))
+		return 0;
+
+	if (fp->rates & SNDRV_PCM_RATE_CONTINUOUS) {
+		if (rate < fp->rate_min || rate > fp->rate_max)
+			return 0;
+	} else {
+		for (i = 0; i < fp->nr_rates; i++) {
+			if (fp->rate_table[i] == rate)
+				break;
+		}
+		if (i >= fp->nr_rates)
+			return 0;
+	}
+
+	score = 1;
+	if (fp->channels == channels)
+		score++;
+
+	return score;
+}
+
+static struct snd_usb_substream *
+find_matching_substream(struct snd_usb_audio *chip, int stream, int ep_num,
+			int fmt_type)
+{
+	struct snd_usb_stream *as;
+	struct snd_usb_substream *subs;
+
+	list_for_each_entry(as, &chip->pcm_list, list) {
+		subs = &as->substream[stream];
+		if (as->fmt_type == fmt_type && subs->ep_num == ep_num)
+			return subs;
+	}
+
+	return NULL;
+}
+
+/*
+ * Return the audioformat that is suitable for the implicit fb
+ */
+const struct audioformat *
+snd_usb_find_implicit_fb_sync_format(struct snd_usb_audio *chip,
+				     const struct audioformat *target,
+				     const struct snd_pcm_hw_params *params,
+				     int stream,
+				     bool *fixed_rate)
+{
+	struct snd_usb_substream *subs;
+	const struct audioformat *fp, *sync_fmt = NULL;
+	int score, high_score;
+
+	/* Use the original audioformat as fallback for the shared altset */
+	if (target->iface == target->sync_iface &&
+	    target->altsetting == target->sync_altsetting)
+		sync_fmt = target;
+
+	subs = find_matching_substream(chip, stream, target->sync_ep,
+				       target->fmt_type);
+	if (!subs)
+		goto end;
+
+	high_score = 0;
+	list_for_each_entry(fp, &subs->fmt_list, list) {
+		score = match_endpoint_audioformats(subs, fp,
+						    params_rate(params),
+						    params_channels(params),
+						    params_format(params));
+		if (score > high_score) {
+			sync_fmt = fp;
+			high_score = score;
+		}
+	}
+
+ end:
+	if (fixed_rate)
+		*fixed_rate = snd_usb_pcm_has_fixed_rate(subs);
+	return sync_fmt;
+}
+