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linux-sg2042/sound/usb/endpoint.c

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// SPDX-License-Identifier: GPL-2.0-or-later
/*
*/
#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/ratelimit.h>
#include <linux/usb.h>
#include <linux/usb/audio.h>
#include <linux/slab.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include "usbaudio.h"
#include "helper.h"
#include "card.h"
#include "endpoint.h"
#include "pcm.h"
#include "clock.h"
#include "quirks.h"
enum {
EP_STATE_STOPPED,
EP_STATE_RUNNING,
EP_STATE_STOPPING,
};
/* interface refcounting */
struct snd_usb_iface_ref {
unsigned char iface;
bool need_setup;
int opened;
struct list_head list;
};
/*
* snd_usb_endpoint is a model that abstracts everything related to an
* USB endpoint and its streaming.
*
* There are functions to activate and deactivate the streaming URBs and
* optional callbacks to let the pcm logic handle the actual content of the
* packets for playback and record. Thus, the bus streaming and the audio
* handlers are fully decoupled.
*
* There are two different types of endpoints in audio applications.
*
* SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
* inbound and outbound traffic.
*
* SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
* expect the payload to carry Q10.14 / Q16.16 formatted sync information
* (3 or 4 bytes).
*
* Each endpoint has to be configured prior to being used by calling
* snd_usb_endpoint_set_params().
*
* The model incorporates a reference counting, so that multiple users
* can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
* only the first user will effectively start the URBs, and only the last
* one to stop it will tear the URBs down again.
*/
/*
* convert a sampling rate into our full speed format (fs/1000 in Q16.16)
* this will overflow at approx 524 kHz
*/
static inline unsigned get_usb_full_speed_rate(unsigned int rate)
{
return ((rate << 13) + 62) / 125;
}
/*
* convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
* this will overflow at approx 4 MHz
*/
static inline unsigned get_usb_high_speed_rate(unsigned int rate)
{
return ((rate << 10) + 62) / 125;
}
/*
* release a urb data
*/
static void release_urb_ctx(struct snd_urb_ctx *u)
{
if (u->buffer_size)
usb_free_coherent(u->ep->chip->dev, u->buffer_size,
u->urb->transfer_buffer,
u->urb->transfer_dma);
usb_free_urb(u->urb);
u->urb = NULL;
}
static const char *usb_error_string(int err)
{
switch (err) {
case -ENODEV:
return "no device";
case -ENOENT:
return "endpoint not enabled";
case -EPIPE:
return "endpoint stalled";
case -ENOSPC:
return "not enough bandwidth";
case -ESHUTDOWN:
return "device disabled";
case -EHOSTUNREACH:
return "device suspended";
case -EINVAL:
case -EAGAIN:
case -EFBIG:
case -EMSGSIZE:
return "internal error";
default:
return "unknown error";
}
}
static inline bool ep_state_running(struct snd_usb_endpoint *ep)
{
return atomic_read(&ep->state) == EP_STATE_RUNNING;
}
static inline bool ep_state_update(struct snd_usb_endpoint *ep, int old, int new)
{
return atomic_cmpxchg(&ep->state, old, new) == old;
}
/**
* snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
*
* @ep: The snd_usb_endpoint
*
* Determine whether an endpoint is driven by an implicit feedback
* data endpoint source.
*/
int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep)
{
return ep->implicit_fb_sync && usb_pipeout(ep->pipe);
}
/*
* Return the number of samples to be sent in the next packet
* for streaming based on information derived from sync endpoints
*
* This won't be used for implicit feedback which takes the packet size
* returned from the sync source
*/
static int slave_next_packet_size(struct snd_usb_endpoint *ep)
{
unsigned long flags;
int ret;
if (ep->fill_max)
return ep->maxframesize;
spin_lock_irqsave(&ep->lock, flags);
ep->phase = (ep->phase & 0xffff)
+ (ep->freqm << ep->datainterval);
ret = min(ep->phase >> 16, ep->maxframesize);
spin_unlock_irqrestore(&ep->lock, flags);
return ret;
}
/*
* Return the number of samples to be sent in the next packet
* for adaptive and synchronous endpoints
*/
static int next_packet_size(struct snd_usb_endpoint *ep)
{
int ret;
if (ep->fill_max)
return ep->maxframesize;
ep->sample_accum += ep->sample_rem;
if (ep->sample_accum >= ep->pps) {
ep->sample_accum -= ep->pps;
ret = ep->packsize[1];
} else {
ret = ep->packsize[0];
}
return ret;
}
/*
* snd_usb_endpoint_next_packet_size: Return the number of samples to be sent
* in the next packet
*/
int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep,
struct snd_urb_ctx *ctx, int idx)
{
if (ctx->packet_size[idx])
return ctx->packet_size[idx];
else if (ep->sync_source)
return slave_next_packet_size(ep);
else
return next_packet_size(ep);
}
static void call_retire_callback(struct snd_usb_endpoint *ep,
struct urb *urb)
{
struct snd_usb_substream *data_subs;
data_subs = READ_ONCE(ep->data_subs);
if (data_subs && ep->retire_data_urb)
ep->retire_data_urb(data_subs, urb);
}
static void retire_outbound_urb(struct snd_usb_endpoint *ep,
struct snd_urb_ctx *urb_ctx)
{
call_retire_callback(ep, urb_ctx->urb);
}
static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
struct snd_usb_endpoint *sender,
const struct urb *urb);
static void retire_inbound_urb(struct snd_usb_endpoint *ep,
struct snd_urb_ctx *urb_ctx)
{
struct urb *urb = urb_ctx->urb;
struct snd_usb_endpoint *sync_sink;
if (unlikely(ep->skip_packets > 0)) {
ep->skip_packets--;
return;
}
sync_sink = READ_ONCE(ep->sync_sink);
if (sync_sink)
snd_usb_handle_sync_urb(sync_sink, ep, urb);
call_retire_callback(ep, urb);
}
static inline bool has_tx_length_quirk(struct snd_usb_audio *chip)
{
return chip->quirk_flags & QUIRK_FLAG_TX_LENGTH;
}
static void prepare_silent_urb(struct snd_usb_endpoint *ep,
struct snd_urb_ctx *ctx)
{
struct urb *urb = ctx->urb;
unsigned int offs = 0;
unsigned int extra = 0;
__le32 packet_length;
int i;
/* For tx_length_quirk, put packet length at start of packet */
if (has_tx_length_quirk(ep->chip))
extra = sizeof(packet_length);
for (i = 0; i < ctx->packets; ++i) {
unsigned int offset;
unsigned int length;
int counts;
counts = snd_usb_endpoint_next_packet_size(ep, ctx, i);
length = counts * ep->stride; /* number of silent bytes */
offset = offs * ep->stride + extra * i;
urb->iso_frame_desc[i].offset = offset;
urb->iso_frame_desc[i].length = length + extra;
if (extra) {
packet_length = cpu_to_le32(length);
memcpy(urb->transfer_buffer + offset,
&packet_length, sizeof(packet_length));
}
memset(urb->transfer_buffer + offset + extra,
ep->silence_value, length);
offs += counts;
}
urb->number_of_packets = ctx->packets;
urb->transfer_buffer_length = offs * ep->stride + ctx->packets * extra;
ctx->queued = 0;
}
/*
* Prepare a PLAYBACK urb for submission to the bus.
*/
static void prepare_outbound_urb(struct snd_usb_endpoint *ep,
struct snd_urb_ctx *ctx)
{
struct urb *urb = ctx->urb;
unsigned char *cp = urb->transfer_buffer;
struct snd_usb_substream *data_subs;
urb->dev = ep->chip->dev; /* we need to set this at each time */
switch (ep->type) {
case SND_USB_ENDPOINT_TYPE_DATA:
data_subs = READ_ONCE(ep->data_subs);
if (data_subs && ep->prepare_data_urb)
ep->prepare_data_urb(data_subs, urb);
else /* no data provider, so send silence */
prepare_silent_urb(ep, ctx);
break;
case SND_USB_ENDPOINT_TYPE_SYNC:
if (snd_usb_get_speed(ep->chip->dev) >= USB_SPEED_HIGH) {
/*
* fill the length and offset of each urb descriptor.
* the fixed 12.13 frequency is passed as 16.16 through the pipe.
*/
urb->iso_frame_desc[0].length = 4;
urb->iso_frame_desc[0].offset = 0;
cp[0] = ep->freqn;
cp[1] = ep->freqn >> 8;
cp[2] = ep->freqn >> 16;
cp[3] = ep->freqn >> 24;
} else {
/*
* fill the length and offset of each urb descriptor.
* the fixed 10.14 frequency is passed through the pipe.
*/
urb->iso_frame_desc[0].length = 3;
urb->iso_frame_desc[0].offset = 0;
cp[0] = ep->freqn >> 2;
cp[1] = ep->freqn >> 10;
cp[2] = ep->freqn >> 18;
}
break;
}
}
/*
* Prepare a CAPTURE or SYNC urb for submission to the bus.
*/
static inline void prepare_inbound_urb(struct snd_usb_endpoint *ep,
struct snd_urb_ctx *urb_ctx)
{
int i, offs;
struct urb *urb = urb_ctx->urb;
urb->dev = ep->chip->dev; /* we need to set this at each time */
switch (ep->type) {
case SND_USB_ENDPOINT_TYPE_DATA:
offs = 0;
for (i = 0; i < urb_ctx->packets; i++) {
urb->iso_frame_desc[i].offset = offs;
urb->iso_frame_desc[i].length = ep->curpacksize;
offs += ep->curpacksize;
}
urb->transfer_buffer_length = offs;
urb->number_of_packets = urb_ctx->packets;
break;
case SND_USB_ENDPOINT_TYPE_SYNC:
urb->iso_frame_desc[0].length = min(4u, ep->syncmaxsize);
urb->iso_frame_desc[0].offset = 0;
break;
}
}
/* notify an error as XRUN to the assigned PCM data substream */
static void notify_xrun(struct snd_usb_endpoint *ep)
{
struct snd_usb_substream *data_subs;
data_subs = READ_ONCE(ep->data_subs);
if (data_subs && data_subs->pcm_substream)
snd_pcm_stop_xrun(data_subs->pcm_substream);
}
static struct snd_usb_packet_info *
next_packet_fifo_enqueue(struct snd_usb_endpoint *ep)
{
struct snd_usb_packet_info *p;
p = ep->next_packet + (ep->next_packet_head + ep->next_packet_queued) %
ARRAY_SIZE(ep->next_packet);
ep->next_packet_queued++;
return p;
}
static struct snd_usb_packet_info *
next_packet_fifo_dequeue(struct snd_usb_endpoint *ep)
{
struct snd_usb_packet_info *p;
p = ep->next_packet + ep->next_packet_head;
ep->next_packet_head++;
ep->next_packet_head %= ARRAY_SIZE(ep->next_packet);
ep->next_packet_queued--;
return p;
}
/*
* Send output urbs that have been prepared previously. URBs are dequeued
* from ep->ready_playback_urbs and in case there aren't any available
* or there are no packets that have been prepared, this function does
* nothing.
*
* The reason why the functionality of sending and preparing URBs is separated
* is that host controllers don't guarantee the order in which they return
* inbound and outbound packets to their submitters.
*
* This function is only used for implicit feedback endpoints. For endpoints
* driven by dedicated sync endpoints, URBs are immediately re-submitted
* from their completion handler.
*/
static void queue_pending_output_urbs(struct snd_usb_endpoint *ep)
{
while (ep_state_running(ep)) {
unsigned long flags;
struct snd_usb_packet_info *packet;
struct snd_urb_ctx *ctx = NULL;
int err, i;
spin_lock_irqsave(&ep->lock, flags);
if (ep->next_packet_queued > 0 &&
!list_empty(&ep->ready_playback_urbs)) {
/* take URB out of FIFO */
ctx = list_first_entry(&ep->ready_playback_urbs,
struct snd_urb_ctx, ready_list);
list_del_init(&ctx->ready_list);
packet = next_packet_fifo_dequeue(ep);
}
spin_unlock_irqrestore(&ep->lock, flags);
if (ctx == NULL)
return;
/* copy over the length information */
for (i = 0; i < packet->packets; i++)
ctx->packet_size[i] = packet->packet_size[i];
/* call the data handler to fill in playback data */
prepare_outbound_urb(ep, ctx);
err = usb_submit_urb(ctx->urb, GFP_ATOMIC);
if (err < 0) {
usb_audio_err(ep->chip,
"Unable to submit urb #%d: %d at %s\n",
ctx->index, err, __func__);
notify_xrun(ep);
return;
}
set_bit(ctx->index, &ep->active_mask);
}
}
/*
* complete callback for urbs
*/
static void snd_complete_urb(struct urb *urb)
{
struct snd_urb_ctx *ctx = urb->context;
struct snd_usb_endpoint *ep = ctx->ep;
unsigned long flags;
int err;
if (unlikely(urb->status == -ENOENT || /* unlinked */
urb->status == -ENODEV || /* device removed */
urb->status == -ECONNRESET || /* unlinked */
urb->status == -ESHUTDOWN)) /* device disabled */
goto exit_clear;
/* device disconnected */
if (unlikely(atomic_read(&ep->chip->shutdown)))
goto exit_clear;
if (unlikely(!ep_state_running(ep)))
goto exit_clear;
if (usb_pipeout(ep->pipe)) {
retire_outbound_urb(ep, ctx);
/* can be stopped during retire callback */
if (unlikely(!ep_state_running(ep)))
goto exit_clear;
if (snd_usb_endpoint_implicit_feedback_sink(ep)) {
spin_lock_irqsave(&ep->lock, flags);
list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
clear_bit(ctx->index, &ep->active_mask);
spin_unlock_irqrestore(&ep->lock, flags);
queue_pending_output_urbs(ep);
return;
}
prepare_outbound_urb(ep, ctx);
/* can be stopped during prepare callback */
if (unlikely(!ep_state_running(ep)))
goto exit_clear;
} else {
retire_inbound_urb(ep, ctx);
/* can be stopped during retire callback */
if (unlikely(!ep_state_running(ep)))
goto exit_clear;
prepare_inbound_urb(ep, ctx);
}
err = usb_submit_urb(urb, GFP_ATOMIC);
if (err == 0)
return;
usb_audio_err(ep->chip, "cannot submit urb (err = %d)\n", err);
notify_xrun(ep);
exit_clear:
clear_bit(ctx->index, &ep->active_mask);
}
/*
* Find or create a refcount object for the given interface
*
* The objects are released altogether in snd_usb_endpoint_free_all()
*/
static struct snd_usb_iface_ref *
iface_ref_find(struct snd_usb_audio *chip, int iface)
{
struct snd_usb_iface_ref *ip;
list_for_each_entry(ip, &chip->iface_ref_list, list)
if (ip->iface == iface)
return ip;
ip = kzalloc(sizeof(*ip), GFP_KERNEL);
if (!ip)
return NULL;
ip->iface = iface;
list_add_tail(&ip->list, &chip->iface_ref_list);
return ip;
}
/*
* Get the existing endpoint object corresponding EP
* Returns NULL if not present.
*/
struct snd_usb_endpoint *
snd_usb_get_endpoint(struct snd_usb_audio *chip, int ep_num)
{
struct snd_usb_endpoint *ep;
list_for_each_entry(ep, &chip->ep_list, list) {
if (ep->ep_num == ep_num)
return ep;
}
return NULL;
}
#define ep_type_name(type) \
(type == SND_USB_ENDPOINT_TYPE_DATA ? "data" : "sync")
/**
* snd_usb_add_endpoint: Add an endpoint to an USB audio chip
*
* @chip: The chip
* @ep_num: The number of the endpoint to use
* @type: SND_USB_ENDPOINT_TYPE_DATA or SND_USB_ENDPOINT_TYPE_SYNC
*
* If the requested endpoint has not been added to the given chip before,
* a new instance is created.
*
* Returns zero on success or a negative error code.
*
* New endpoints will be added to chip->ep_list and freed by
* calling snd_usb_endpoint_free_all().
*
* For SND_USB_ENDPOINT_TYPE_SYNC, the caller needs to guarantee that
* bNumEndpoints > 1 beforehand.
*/
int snd_usb_add_endpoint(struct snd_usb_audio *chip, int ep_num, int type)
{
struct snd_usb_endpoint *ep;
bool is_playback;
ep = snd_usb_get_endpoint(chip, ep_num);
if (ep)
return 0;
usb_audio_dbg(chip, "Creating new %s endpoint #%x\n",
ep_type_name(type),
ep_num);
ep = kzalloc(sizeof(*ep), GFP_KERNEL);
if (!ep)
return -ENOMEM;
ep->chip = chip;
spin_lock_init(&ep->lock);
ep->type = type;
ep->ep_num = ep_num;
INIT_LIST_HEAD(&ep->ready_playback_urbs);
is_playback = ((ep_num & USB_ENDPOINT_DIR_MASK) == USB_DIR_OUT);
ep_num &= USB_ENDPOINT_NUMBER_MASK;
if (is_playback)
ep->pipe = usb_sndisocpipe(chip->dev, ep_num);
else
ep->pipe = usb_rcvisocpipe(chip->dev, ep_num);
list_add_tail(&ep->list, &chip->ep_list);
return 0;
}
/* Set up syncinterval and maxsyncsize for a sync EP */
static void endpoint_set_syncinterval(struct snd_usb_audio *chip,
struct snd_usb_endpoint *ep)
{
struct usb_host_interface *alts;
struct usb_endpoint_descriptor *desc;
alts = snd_usb_get_host_interface(chip, ep->iface, ep->altsetting);
if (!alts)
return;
desc = get_endpoint(alts, ep->ep_idx);
if (desc->bLength >= USB_DT_ENDPOINT_AUDIO_SIZE &&
desc->bRefresh >= 1 && desc->bRefresh <= 9)
ep->syncinterval = desc->bRefresh;
else if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL)
ep->syncinterval = 1;
else if (desc->bInterval >= 1 && desc->bInterval <= 16)
ep->syncinterval = desc->bInterval - 1;
else
ep->syncinterval = 3;
ep->syncmaxsize = le16_to_cpu(desc->wMaxPacketSize);
}
static bool endpoint_compatible(struct snd_usb_endpoint *ep,
const struct audioformat *fp,
const struct snd_pcm_hw_params *params)
{
if (!ep->opened)
return false;
if (ep->cur_audiofmt != fp)
return false;
if (ep->cur_rate != params_rate(params) ||
ep->cur_format != params_format(params) ||
ep->cur_period_frames != params_period_size(params) ||
ep->cur_buffer_periods != params_periods(params))
return false;
return true;
}
/*
* Check whether the given fp and hw params are compatible with the current
* setup of the target EP for implicit feedback sync
*/
bool snd_usb_endpoint_compatible(struct snd_usb_audio *chip,
struct snd_usb_endpoint *ep,
const struct audioformat *fp,
const struct snd_pcm_hw_params *params)
{
bool ret;
mutex_lock(&chip->mutex);
ret = endpoint_compatible(ep, fp, params);
mutex_unlock(&chip->mutex);
return ret;
}
/*
* snd_usb_endpoint_open: Open the endpoint
*
* Called from hw_params to assign the endpoint to the substream.
* It's reference-counted, and only the first opener is allowed to set up
* arbitrary parameters. The later opener must be compatible with the
* former opened parameters.
* The endpoint needs to be closed via snd_usb_endpoint_close() later.
*
* Note that this function doesn't configure the endpoint. The substream
* needs to set it up later via snd_usb_endpoint_configure().
*/
struct snd_usb_endpoint *
snd_usb_endpoint_open(struct snd_usb_audio *chip,
const struct audioformat *fp,
const struct snd_pcm_hw_params *params,
bool is_sync_ep)
{
struct snd_usb_endpoint *ep;
int ep_num = is_sync_ep ? fp->sync_ep : fp->endpoint;
mutex_lock(&chip->mutex);
ep = snd_usb_get_endpoint(chip, ep_num);
if (!ep) {
usb_audio_err(chip, "Cannot find EP 0x%x to open\n", ep_num);
goto unlock;
}
if (!ep->opened) {
if (is_sync_ep) {
ep->iface = fp->sync_iface;
ep->altsetting = fp->sync_altsetting;
ep->ep_idx = fp->sync_ep_idx;
} else {
ep->iface = fp->iface;
ep->altsetting = fp->altsetting;
ep->ep_idx = fp->ep_idx;
}
usb_audio_dbg(chip, "Open EP 0x%x, iface=%d:%d, idx=%d\n",
ep_num, ep->iface, ep->altsetting, ep->ep_idx);
ep->iface_ref = iface_ref_find(chip, ep->iface);
if (!ep->iface_ref) {
ep = NULL;
goto unlock;
}
ep->cur_audiofmt = fp;
ep->cur_channels = fp->channels;
ep->cur_rate = params_rate(params);
ep->cur_format = params_format(params);
ep->cur_frame_bytes = snd_pcm_format_physical_width(ep->cur_format) *
ep->cur_channels / 8;
ep->cur_period_frames = params_period_size(params);
ep->cur_period_bytes = ep->cur_period_frames * ep->cur_frame_bytes;
ep->cur_buffer_periods = params_periods(params);
if (ep->type == SND_USB_ENDPOINT_TYPE_SYNC)
endpoint_set_syncinterval(chip, ep);
ep->implicit_fb_sync = fp->implicit_fb;
ep->need_setup = true;
usb_audio_dbg(chip, " channels=%d, rate=%d, format=%s, period_bytes=%d, periods=%d, implicit_fb=%d\n",
ep->cur_channels, ep->cur_rate,
snd_pcm_format_name(ep->cur_format),
ep->cur_period_bytes, ep->cur_buffer_periods,
ep->implicit_fb_sync);
} else {
if (WARN_ON(!ep->iface_ref)) {
ep = NULL;
goto unlock;
}
if (!endpoint_compatible(ep, fp, params)) {
usb_audio_err(chip, "Incompatible EP setup for 0x%x\n",
ep_num);
ep = NULL;
goto unlock;
}
usb_audio_dbg(chip, "Reopened EP 0x%x (count %d)\n",
ep_num, ep->opened);
}
if (!ep->iface_ref->opened++)
ep->iface_ref->need_setup = true;
ep->opened++;
unlock:
mutex_unlock(&chip->mutex);
return ep;
}
/*
* snd_usb_endpoint_set_sync: Link data and sync endpoints
*
* Pass NULL to sync_ep to unlink again
*/
void snd_usb_endpoint_set_sync(struct snd_usb_audio *chip,
struct snd_usb_endpoint *data_ep,
struct snd_usb_endpoint *sync_ep)
{
data_ep->sync_source = sync_ep;
}
/*
* Set data endpoint callbacks and the assigned data stream
*
* Called at PCM trigger and cleanups.
* Pass NULL to deactivate each callback.
*/
void snd_usb_endpoint_set_callback(struct snd_usb_endpoint *ep,
void (*prepare)(struct snd_usb_substream *subs,
struct urb *urb),
void (*retire)(struct snd_usb_substream *subs,
struct urb *urb),
struct snd_usb_substream *data_subs)
{
ep->prepare_data_urb = prepare;
ep->retire_data_urb = retire;
WRITE_ONCE(ep->data_subs, data_subs);
}
static int endpoint_set_interface(struct snd_usb_audio *chip,
struct snd_usb_endpoint *ep,
bool set)
{
int altset = set ? ep->altsetting : 0;
int err;
usb_audio_dbg(chip, "Setting usb interface %d:%d for EP 0x%x\n",
ep->iface, altset, ep->ep_num);
err = usb_set_interface(chip->dev, ep->iface, altset);
if (err < 0) {
usb_audio_err(chip, "%d:%d: usb_set_interface failed (%d)\n",
ep->iface, altset, err);
return err;
}
if (chip->quirk_flags & QUIRK_FLAG_IFACE_DELAY)
msleep(50);
return 0;
}
/*
* snd_usb_endpoint_close: Close the endpoint
*
* Unreference the already opened endpoint via snd_usb_endpoint_open().
*/
void snd_usb_endpoint_close(struct snd_usb_audio *chip,
struct snd_usb_endpoint *ep)
{
mutex_lock(&chip->mutex);
usb_audio_dbg(chip, "Closing EP 0x%x (count %d)\n",
ep->ep_num, ep->opened);
if (!--ep->iface_ref->opened)
endpoint_set_interface(chip, ep, false);
if (!--ep->opened) {
ep->iface = 0;
ep->altsetting = 0;
ep->cur_audiofmt = NULL;
ep->cur_rate = 0;
ep->iface_ref = NULL;
usb_audio_dbg(chip, "EP 0x%x closed\n", ep->ep_num);
}
mutex_unlock(&chip->mutex);
}
/* Prepare for suspening EP, called from the main suspend handler */
void snd_usb_endpoint_suspend(struct snd_usb_endpoint *ep)
{
ep->need_setup = true;
if (ep->iface_ref)
ep->iface_ref->need_setup = true;
}
/*
* wait until all urbs are processed.
*/
static int wait_clear_urbs(struct snd_usb_endpoint *ep)
{
unsigned long end_time = jiffies + msecs_to_jiffies(1000);
int alive;
if (atomic_read(&ep->state) != EP_STATE_STOPPING)
return 0;
do {
alive = bitmap_weight(&ep->active_mask, ep->nurbs);
if (!alive)
break;
schedule_timeout_uninterruptible(1);
} while (time_before(jiffies, end_time));
if (alive)
usb_audio_err(ep->chip,
"timeout: still %d active urbs on EP #%x\n",
alive, ep->ep_num);
if (ep_state_update(ep, EP_STATE_STOPPING, EP_STATE_STOPPED)) {
ep->sync_sink = NULL;
snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
}
return 0;
}
/* sync the pending stop operation;
* this function itself doesn't trigger the stop operation
*/
void snd_usb_endpoint_sync_pending_stop(struct snd_usb_endpoint *ep)
{
if (ep)
wait_clear_urbs(ep);
}
/*
* Stop active urbs
*
* This function moves the EP to STOPPING state if it's being RUNNING.
*/
static int stop_urbs(struct snd_usb_endpoint *ep, bool force)
{
unsigned int i;
if (!force && atomic_read(&ep->running))
return -EBUSY;
if (!ep_state_update(ep, EP_STATE_RUNNING, EP_STATE_STOPPING))
return 0;
INIT_LIST_HEAD(&ep->ready_playback_urbs);
ep->next_packet_head = 0;
ep->next_packet_queued = 0;
for (i = 0; i < ep->nurbs; i++) {
if (test_bit(i, &ep->active_mask)) {
if (!test_and_set_bit(i, &ep->unlink_mask)) {
struct urb *u = ep->urb[i].urb;
usb_unlink_urb(u);
}
}
}
return 0;
}
/*
* release an endpoint's urbs
*/
static int release_urbs(struct snd_usb_endpoint *ep, bool force)
{
int i, err;
/* route incoming urbs to nirvana */
snd_usb_endpoint_set_callback(ep, NULL, NULL, NULL);
/* stop and unlink urbs */
err = stop_urbs(ep, force);
if (err)
return err;
wait_clear_urbs(ep);
for (i = 0; i < ep->nurbs; i++)
release_urb_ctx(&ep->urb[i]);
usb_free_coherent(ep->chip->dev, SYNC_URBS * 4,
ep->syncbuf, ep->sync_dma);
ep->syncbuf = NULL;
ep->nurbs = 0;
return 0;
}
/*
* configure a data endpoint
*/
static int data_ep_set_params(struct snd_usb_endpoint *ep)
{
struct snd_usb_audio *chip = ep->chip;
unsigned int maxsize, minsize, packs_per_ms, max_packs_per_urb;
unsigned int max_packs_per_period, urbs_per_period, urb_packs;
unsigned int max_urbs, i;
const struct audioformat *fmt = ep->cur_audiofmt;
int frame_bits = ep->cur_frame_bytes * 8;
int tx_length_quirk = (has_tx_length_quirk(chip) &&
usb_pipeout(ep->pipe));
usb_audio_dbg(chip, "Setting params for data EP 0x%x, pipe 0x%x\n",
ep->ep_num, ep->pipe);
if (ep->cur_format == SNDRV_PCM_FORMAT_DSD_U16_LE && fmt->dsd_dop) {
/*
* When operating in DSD DOP mode, the size of a sample frame
* in hardware differs from the actual physical format width
* because we need to make room for the DOP markers.
*/
frame_bits += ep->cur_channels << 3;
}
ep->datainterval = fmt->datainterval;
ep->stride = frame_bits >> 3;
switch (ep->cur_format) {
case SNDRV_PCM_FORMAT_U8:
ep->silence_value = 0x80;
break;
case SNDRV_PCM_FORMAT_DSD_U8:
case SNDRV_PCM_FORMAT_DSD_U16_LE:
case SNDRV_PCM_FORMAT_DSD_U32_LE:
case SNDRV_PCM_FORMAT_DSD_U16_BE:
case SNDRV_PCM_FORMAT_DSD_U32_BE:
ep->silence_value = 0x69;
break;
default:
ep->silence_value = 0;
}
/* assume max. frequency is 50% higher than nominal */
ep->freqmax = ep->freqn + (ep->freqn >> 1);
/* Round up freqmax to nearest integer in order to calculate maximum
* packet size, which must represent a whole number of frames.
* This is accomplished by adding 0x0.ffff before converting the
* Q16.16 format into integer.
* In order to accurately calculate the maximum packet size when
* the data interval is more than 1 (i.e. ep->datainterval > 0),
* multiply by the data interval prior to rounding. For instance,
* a freqmax of 41 kHz will result in a max packet size of 6 (5.125)
* frames with a data interval of 1, but 11 (10.25) frames with a
* data interval of 2.
* (ep->freqmax << ep->datainterval overflows at 8.192 MHz for the
* maximum datainterval value of 3, at USB full speed, higher for
* USB high speed, noting that ep->freqmax is in units of
* frames per packet in Q16.16 format.)
*/
maxsize = (((ep->freqmax << ep->datainterval) + 0xffff) >> 16) *
(frame_bits >> 3);
if (tx_length_quirk)
maxsize += sizeof(__le32); /* Space for length descriptor */
/* but wMaxPacketSize might reduce this */
if (ep->maxpacksize && ep->maxpacksize < maxsize) {
/* whatever fits into a max. size packet */
unsigned int data_maxsize = maxsize = ep->maxpacksize;
if (tx_length_quirk)
/* Need to remove the length descriptor to calc freq */
data_maxsize -= sizeof(__le32);
ep->freqmax = (data_maxsize / (frame_bits >> 3))
<< (16 - ep->datainterval);
}
if (ep->fill_max)
ep->curpacksize = ep->maxpacksize;
else
ep->curpacksize = maxsize;
if (snd_usb_get_speed(chip->dev) != USB_SPEED_FULL) {
packs_per_ms = 8 >> ep->datainterval;
max_packs_per_urb = MAX_PACKS_HS;
} else {
packs_per_ms = 1;
max_packs_per_urb = MAX_PACKS;
}
if (ep->sync_source && !ep->implicit_fb_sync)
max_packs_per_urb = min(max_packs_per_urb,
1U << ep->sync_source->syncinterval);
max_packs_per_urb = max(1u, max_packs_per_urb >> ep->datainterval);
/*
* Capture endpoints need to use small URBs because there's no way
* to tell in advance where the next period will end, and we don't
* want the next URB to complete much after the period ends.
*
* Playback endpoints with implicit sync much use the same parameters
* as their corresponding capture endpoint.
*/
if (usb_pipein(ep->pipe) || ep->implicit_fb_sync) {
urb_packs = packs_per_ms;
/*
* Wireless devices can poll at a max rate of once per 4ms.
* For dataintervals less than 5, increase the packet count to
* allow the host controller to use bursting to fill in the
* gaps.
*/
if (snd_usb_get_speed(chip->dev) == USB_SPEED_WIRELESS) {
int interval = ep->datainterval;
while (interval < 5) {
urb_packs <<= 1;
++interval;
}
}
/* make capture URBs <= 1 ms and smaller than a period */
urb_packs = min(max_packs_per_urb, urb_packs);
while (urb_packs > 1 && urb_packs * maxsize >= ep->cur_period_bytes)
urb_packs >>= 1;
ep->nurbs = MAX_URBS;
/*
* Playback endpoints without implicit sync are adjusted so that
* a period fits as evenly as possible in the smallest number of
* URBs. The total number of URBs is adjusted to the size of the
* ALSA buffer, subject to the MAX_URBS and MAX_QUEUE limits.
*/
} else {
/* determine how small a packet can be */
minsize = (ep->freqn >> (16 - ep->datainterval)) *
(frame_bits >> 3);
/* with sync from device, assume it can be 12% lower */
if (ep->sync_source)
minsize -= minsize >> 3;
minsize = max(minsize, 1u);
/* how many packets will contain an entire ALSA period? */
max_packs_per_period = DIV_ROUND_UP(ep->cur_period_bytes, minsize);
/* how many URBs will contain a period? */
urbs_per_period = DIV_ROUND_UP(max_packs_per_period,
max_packs_per_urb);
/* how many packets are needed in each URB? */
urb_packs = DIV_ROUND_UP(max_packs_per_period, urbs_per_period);
/* limit the number of frames in a single URB */
ep->max_urb_frames = DIV_ROUND_UP(ep->cur_period_frames,
urbs_per_period);
/* try to use enough URBs to contain an entire ALSA buffer */
max_urbs = min((unsigned) MAX_URBS,
MAX_QUEUE * packs_per_ms / urb_packs);
ep->nurbs = min(max_urbs, urbs_per_period * ep->cur_buffer_periods);
}
/* allocate and initialize data urbs */
for (i = 0; i < ep->nurbs; i++) {
struct snd_urb_ctx *u = &ep->urb[i];
u->index = i;
u->ep = ep;
u->packets = urb_packs;
u->buffer_size = maxsize * u->packets;
if (fmt->fmt_type == UAC_FORMAT_TYPE_II)
u->packets++; /* for transfer delimiter */
u->urb = usb_alloc_urb(u->packets, GFP_KERNEL);
if (!u->urb)
goto out_of_memory;
u->urb->transfer_buffer =
usb_alloc_coherent(chip->dev, u->buffer_size,
GFP_KERNEL, &u->urb->transfer_dma);
if (!u->urb->transfer_buffer)
goto out_of_memory;
u->urb->pipe = ep->pipe;
u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
u->urb->interval = 1 << ep->datainterval;
u->urb->context = u;
u->urb->complete = snd_complete_urb;
INIT_LIST_HEAD(&u->ready_list);
}
/* total buffer bytes of all URBs plus the next queue;
* referred in pcm.c
*/
ep->nominal_queue_size = maxsize * urb_packs * (ep->nurbs + 1);
return 0;
out_of_memory:
release_urbs(ep, false);
return -ENOMEM;
}
/*
* configure a sync endpoint
*/
static int sync_ep_set_params(struct snd_usb_endpoint *ep)
{
struct snd_usb_audio *chip = ep->chip;
int i;
usb_audio_dbg(chip, "Setting params for sync EP 0x%x, pipe 0x%x\n",
ep->ep_num, ep->pipe);
ep->syncbuf = usb_alloc_coherent(chip->dev, SYNC_URBS * 4,
GFP_KERNEL, &ep->sync_dma);
if (!ep->syncbuf)
return -ENOMEM;
for (i = 0; i < SYNC_URBS; i++) {
struct snd_urb_ctx *u = &ep->urb[i];
u->index = i;
u->ep = ep;
u->packets = 1;
u->urb = usb_alloc_urb(1, GFP_KERNEL);
if (!u->urb)
goto out_of_memory;
u->urb->transfer_buffer = ep->syncbuf + i * 4;
u->urb->transfer_dma = ep->sync_dma + i * 4;
u->urb->transfer_buffer_length = 4;
u->urb->pipe = ep->pipe;
u->urb->transfer_flags = URB_NO_TRANSFER_DMA_MAP;
u->urb->number_of_packets = 1;
u->urb->interval = 1 << ep->syncinterval;
u->urb->context = u;
u->urb->complete = snd_complete_urb;
}
ep->nurbs = SYNC_URBS;
return 0;
out_of_memory:
release_urbs(ep, false);
return -ENOMEM;
}
/*
* snd_usb_endpoint_set_params: configure an snd_usb_endpoint
*
* Determine the number of URBs to be used on this endpoint.
* An endpoint must be configured before it can be started.
* An endpoint that is already running can not be reconfigured.
*/
static int snd_usb_endpoint_set_params(struct snd_usb_audio *chip,
struct snd_usb_endpoint *ep)
{
const struct audioformat *fmt = ep->cur_audiofmt;
int err;
/* release old buffers, if any */
err = release_urbs(ep, false);
if (err < 0)
return err;
ep->datainterval = fmt->datainterval;
ep->maxpacksize = fmt->maxpacksize;
ep->fill_max = !!(fmt->attributes & UAC_EP_CS_ATTR_FILL_MAX);
if (snd_usb_get_speed(chip->dev) == USB_SPEED_FULL) {
ep->freqn = get_usb_full_speed_rate(ep->cur_rate);
ep->pps = 1000 >> ep->datainterval;
} else {
ep->freqn = get_usb_high_speed_rate(ep->cur_rate);
ep->pps = 8000 >> ep->datainterval;
}
ep->sample_rem = ep->cur_rate % ep->pps;
ep->packsize[0] = ep->cur_rate / ep->pps;
ep->packsize[1] = (ep->cur_rate + (ep->pps - 1)) / ep->pps;
/* calculate the frequency in 16.16 format */
ep->freqm = ep->freqn;
ep->freqshift = INT_MIN;
ep->phase = 0;
switch (ep->type) {
case SND_USB_ENDPOINT_TYPE_DATA:
err = data_ep_set_params(ep);
break;
case SND_USB_ENDPOINT_TYPE_SYNC:
err = sync_ep_set_params(ep);
break;
default:
err = -EINVAL;
}
usb_audio_dbg(chip, "Set up %d URBS, ret=%d\n", ep->nurbs, err);
if (err < 0)
return err;
/* some unit conversions in runtime */
ep->maxframesize = ep->maxpacksize / ep->cur_frame_bytes;
ep->curframesize = ep->curpacksize / ep->cur_frame_bytes;
return 0;
}
/*
* snd_usb_endpoint_configure: Configure the endpoint
*
* This function sets up the EP to be fully usable state.
* It's called either from hw_params or prepare callback.
* The function checks need_setup flag, and performs nothing unless needed,
* so it's safe to call this multiple times.
*
* This returns zero if unchanged, 1 if the configuration has changed,
* or a negative error code.
*/
int snd_usb_endpoint_configure(struct snd_usb_audio *chip,
struct snd_usb_endpoint *ep)
{
bool iface_first;
int err = 0;
mutex_lock(&chip->mutex);
if (WARN_ON(!ep->iface_ref))
goto unlock;
if (!ep->need_setup)
goto unlock;
/* If the interface has been already set up, just set EP parameters */
if (!ep->iface_ref->need_setup) {
/* sample rate setup of UAC1 is per endpoint, and we need
* to update at each EP configuration
*/
if (ep->cur_audiofmt->protocol == UAC_VERSION_1) {
err = snd_usb_init_sample_rate(chip, ep->cur_audiofmt,
ep->cur_rate);
if (err < 0)
goto unlock;
}
err = snd_usb_endpoint_set_params(chip, ep);
if (err < 0)
goto unlock;
goto done;
}
/* Need to deselect altsetting at first */
endpoint_set_interface(chip, ep, false);
/* Some UAC1 devices (e.g. Yamaha THR10) need the host interface
* to be set up before parameter setups
*/
iface_first = ep->cur_audiofmt->protocol == UAC_VERSION_1;
/* Workaround for devices that require the interface setup at first like UAC1 */
if (chip->quirk_flags & QUIRK_FLAG_SET_IFACE_FIRST)
iface_first = true;
if (iface_first) {
err = endpoint_set_interface(chip, ep, true);
if (err < 0)
goto unlock;
}
err = snd_usb_init_pitch(chip, ep->cur_audiofmt);
if (err < 0)
goto unlock;
err = snd_usb_init_sample_rate(chip, ep->cur_audiofmt, ep->cur_rate);
if (err < 0)
goto unlock;
err = snd_usb_endpoint_set_params(chip, ep);
if (err < 0)
goto unlock;
err = snd_usb_select_mode_quirk(chip, ep->cur_audiofmt);
if (err < 0)
goto unlock;
/* for UAC2/3, enable the interface altset here at last */
if (!iface_first) {
err = endpoint_set_interface(chip, ep, true);
if (err < 0)
goto unlock;
}
ep->iface_ref->need_setup = false;
done:
ep->need_setup = false;
err = 1;
unlock:
mutex_unlock(&chip->mutex);
return err;
}
/**
* snd_usb_endpoint_start: start an snd_usb_endpoint
*
* @ep: the endpoint to start
*
* A call to this function will increment the running count of the endpoint.
* In case it is not already running, the URBs for this endpoint will be
* submitted. Otherwise, this function does nothing.
*
* Must be balanced to calls of snd_usb_endpoint_stop().
*
* Returns an error if the URB submission failed, 0 in all other cases.
*/
int snd_usb_endpoint_start(struct snd_usb_endpoint *ep)
{
int err;
unsigned int i;
if (atomic_read(&ep->chip->shutdown))
return -EBADFD;
if (ep->sync_source)
WRITE_ONCE(ep->sync_source->sync_sink, ep);
usb_audio_dbg(ep->chip, "Starting %s EP 0x%x (running %d)\n",
ep_type_name(ep->type), ep->ep_num,
atomic_read(&ep->running));
/* already running? */
if (atomic_inc_return(&ep->running) != 1)
return 0;
ep->active_mask = 0;
ep->unlink_mask = 0;
ep->phase = 0;
ep->sample_accum = 0;
snd_usb_endpoint_start_quirk(ep);
/*
* If this endpoint has a data endpoint as implicit feedback source,
* don't start the urbs here. Instead, mark them all as available,
* wait for the record urbs to return and queue the playback urbs
* from that context.
*/
if (!ep_state_update(ep, EP_STATE_STOPPED, EP_STATE_RUNNING))
goto __error;
if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
!(ep->chip->quirk_flags & QUIRK_FLAG_PLAYBACK_FIRST)) {
for (i = 0; i < ep->nurbs; i++) {
struct snd_urb_ctx *ctx = ep->urb + i;
list_add_tail(&ctx->ready_list, &ep->ready_playback_urbs);
}
usb_audio_dbg(ep->chip, "No URB submission due to implicit fb sync\n");
return 0;
}
for (i = 0; i < ep->nurbs; i++) {
struct urb *urb = ep->urb[i].urb;
if (snd_BUG_ON(!urb))
goto __error;
if (usb_pipeout(ep->pipe)) {
prepare_outbound_urb(ep, urb->context);
} else {
prepare_inbound_urb(ep, urb->context);
}
err = usb_submit_urb(urb, GFP_ATOMIC);
if (err < 0) {
usb_audio_err(ep->chip,
"cannot submit urb %d, error %d: %s\n",
i, err, usb_error_string(err));
goto __error;
}
set_bit(i, &ep->active_mask);
}
usb_audio_dbg(ep->chip, "%d URBs submitted for EP 0x%x\n",
ep->nurbs, ep->ep_num);
return 0;
__error:
snd_usb_endpoint_stop(ep);
return -EPIPE;
}
/**
* snd_usb_endpoint_stop: stop an snd_usb_endpoint
*
* @ep: the endpoint to stop (may be NULL)
*
* A call to this function will decrement the running count of the endpoint.
* In case the last user has requested the endpoint stop, the URBs will
* actually be deactivated.
*
* Must be balanced to calls of snd_usb_endpoint_start().
*
* The caller needs to synchronize the pending stop operation via
* snd_usb_endpoint_sync_pending_stop().
*/
void snd_usb_endpoint_stop(struct snd_usb_endpoint *ep)
{
if (!ep)
return;
usb_audio_dbg(ep->chip, "Stopping %s EP 0x%x (running %d)\n",
ep_type_name(ep->type), ep->ep_num,
atomic_read(&ep->running));
if (snd_BUG_ON(!atomic_read(&ep->running)))
return;
if (!atomic_dec_return(&ep->running)) {
if (ep->sync_source)
WRITE_ONCE(ep->sync_source->sync_sink, NULL);
stop_urbs(ep, false);
}
}
/**
* snd_usb_endpoint_release: Tear down an snd_usb_endpoint
*
* @ep: the endpoint to release
*
* This function does not care for the endpoint's running count but will tear
* down all the streaming URBs immediately.
*/
void snd_usb_endpoint_release(struct snd_usb_endpoint *ep)
{
release_urbs(ep, true);
}
/**
* snd_usb_endpoint_free_all: Free the resources of an snd_usb_endpoint
* @chip: The chip
*
* This free all endpoints and those resources
*/
void snd_usb_endpoint_free_all(struct snd_usb_audio *chip)
{
struct snd_usb_endpoint *ep, *en;
struct snd_usb_iface_ref *ip, *in;
list_for_each_entry_safe(ep, en, &chip->ep_list, list)
kfree(ep);
list_for_each_entry_safe(ip, in, &chip->iface_ref_list, list)
kfree(ip);
}
/*
* snd_usb_handle_sync_urb: parse an USB sync packet
*
* @ep: the endpoint to handle the packet
* @sender: the sending endpoint
* @urb: the received packet
*
* This function is called from the context of an endpoint that received
* the packet and is used to let another endpoint object handle the payload.
*/
static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
struct snd_usb_endpoint *sender,
const struct urb *urb)
{
int shift;
unsigned int f;
unsigned long flags;
snd_BUG_ON(ep == sender);
/*
* In case the endpoint is operating in implicit feedback mode, prepare
* a new outbound URB that has the same layout as the received packet
* and add it to the list of pending urbs. queue_pending_output_urbs()
* will take care of them later.
*/
if (snd_usb_endpoint_implicit_feedback_sink(ep) &&
atomic_read(&ep->running)) {
/* implicit feedback case */
int i, bytes = 0;
struct snd_urb_ctx *in_ctx;
struct snd_usb_packet_info *out_packet;
in_ctx = urb->context;
/* Count overall packet size */
for (i = 0; i < in_ctx->packets; i++)
if (urb->iso_frame_desc[i].status == 0)
bytes += urb->iso_frame_desc[i].actual_length;
/*
* skip empty packets. At least M-Audio's Fast Track Ultra stops
* streaming once it received a 0-byte OUT URB
*/
if (bytes == 0)
return;
spin_lock_irqsave(&ep->lock, flags);
if (ep->next_packet_queued >= ARRAY_SIZE(ep->next_packet)) {
spin_unlock_irqrestore(&ep->lock, flags);
usb_audio_err(ep->chip,
"next package FIFO overflow EP 0x%x\n",
ep->ep_num);
notify_xrun(ep);
return;
}
out_packet = next_packet_fifo_enqueue(ep);
/*
* Iterate through the inbound packet and prepare the lengths
* for the output packet. The OUT packet we are about to send
* will have the same amount of payload bytes per stride as the
* IN packet we just received. Since the actual size is scaled
* by the stride, use the sender stride to calculate the length
* in case the number of channels differ between the implicitly
* fed-back endpoint and the synchronizing endpoint.
*/
out_packet->packets = in_ctx->packets;
for (i = 0; i < in_ctx->packets; i++) {
if (urb->iso_frame_desc[i].status == 0)
out_packet->packet_size[i] =
urb->iso_frame_desc[i].actual_length / sender->stride;
else
out_packet->packet_size[i] = 0;
}
spin_unlock_irqrestore(&ep->lock, flags);
queue_pending_output_urbs(ep);
return;
}
/*
* process after playback sync complete
*
* Full speed devices report feedback values in 10.14 format as samples
* per frame, high speed devices in 16.16 format as samples per
* microframe.
*
* Because the Audio Class 1 spec was written before USB 2.0, many high
* speed devices use a wrong interpretation, some others use an
* entirely different format.
*
* Therefore, we cannot predict what format any particular device uses
* and must detect it automatically.
*/
if (urb->iso_frame_desc[0].status != 0 ||
urb->iso_frame_desc[0].actual_length < 3)
return;
f = le32_to_cpup(urb->transfer_buffer);
if (urb->iso_frame_desc[0].actual_length == 3)
f &= 0x00ffffff;
else
f &= 0x0fffffff;
if (f == 0)
return;
if (unlikely(sender->tenor_fb_quirk)) {
/*
* Devices based on Tenor 8802 chipsets (TEAC UD-H01
* and others) sometimes change the feedback value
* by +/- 0x1.0000.
*/
if (f < ep->freqn - 0x8000)
f += 0xf000;
else if (f > ep->freqn + 0x8000)
f -= 0xf000;
} else if (unlikely(ep->freqshift == INT_MIN)) {
/*
* The first time we see a feedback value, determine its format
* by shifting it left or right until it matches the nominal
* frequency value. This assumes that the feedback does not
* differ from the nominal value more than +50% or -25%.
*/
shift = 0;
while (f < ep->freqn - ep->freqn / 4) {
f <<= 1;
shift++;
}
while (f > ep->freqn + ep->freqn / 2) {
f >>= 1;
shift--;
}
ep->freqshift = shift;
} else if (ep->freqshift >= 0)
f <<= ep->freqshift;
else
f >>= -ep->freqshift;
if (likely(f >= ep->freqn - ep->freqn / 8 && f <= ep->freqmax)) {
/*
* If the frequency looks valid, set it.
* This value is referred to in prepare_playback_urb().
*/
spin_lock_irqsave(&ep->lock, flags);
ep->freqm = f;
spin_unlock_irqrestore(&ep->lock, flags);
} else {
/*
* Out of range; maybe the shift value is wrong.
* Reset it so that we autodetect again the next time.
*/
ep->freqshift = INT_MIN;
}
}
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