use pa_alsa_safe_delay() where appropriate

[pulseaudio] / src / modules / alsa / alsa-source.c

/***
  This file is part of PulseAudio.

  Copyright 2004-2008 Lennart Poettering
  Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB

  PulseAudio is free software; you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as published
  by the Free Software Foundation; either version 2 of the License,
  or (at your option) any later version.

  PulseAudio is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with PulseAudio; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  USA.
***/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <stdio.h>

#include <asoundlib.h>

#ifdef HAVE_VALGRIND_MEMCHECK_H
#include <valgrind/memcheck.h>
#endif

#include <pulse/xmalloc.h>
#include <pulse/util.h>
#include <pulse/timeval.h>
#include <pulse/i18n.h>

#include <pulsecore/core-error.h>
#include <pulsecore/core.h>
#include <pulsecore/module.h>
#include <pulsecore/memchunk.h>
#include <pulsecore/sink.h>
#include <pulsecore/modargs.h>
#include <pulsecore/core-util.h>
#include <pulsecore/sample-util.h>
#include <pulsecore/log.h>
#include <pulsecore/macro.h>
#include <pulsecore/thread.h>
#include <pulsecore/core-error.h>
#include <pulsecore/thread-mq.h>
#include <pulsecore/rtpoll.h>
#include <pulsecore/time-smoother.h>
#include <pulsecore/rtclock.h>

#include "alsa-util.h"
#include "alsa-source.h"

/* #define DEBUG_TIMING */

#define DEFAULT_DEVICE "default"
#define DEFAULT_TSCHED_BUFFER_USEC (2*PA_USEC_PER_SEC)       /* 2s */
#define DEFAULT_TSCHED_WATERMARK_USEC (20*PA_USEC_PER_MSEC)  /* 20ms */
#define TSCHED_MIN_SLEEP_USEC (10*PA_USEC_PER_MSEC)          /* 10ms */
#define TSCHED_MIN_WAKEUP_USEC (4*PA_USEC_PER_MSEC)          /* 4ms */

struct userdata {
    pa_core *core;
    pa_module *module;
    pa_source *source;

    pa_thread *thread;
    pa_thread_mq thread_mq;
    pa_rtpoll *rtpoll;

    snd_pcm_t *pcm_handle;

    pa_alsa_fdlist *mixer_fdl;
    snd_mixer_t *mixer_handle;
    snd_mixer_elem_t *mixer_elem;
    long hw_volume_max, hw_volume_min;
    long hw_dB_max, hw_dB_min;
    pa_bool_t hw_dB_supported:1;
    pa_bool_t mixer_seperate_channels:1;

    pa_cvolume hardware_volume;

    size_t frame_size, fragment_size, hwbuf_size, tsched_watermark, hwbuf_unused, min_sleep, min_wakeup;
    unsigned nfragments;

    char *device_name;

    pa_bool_t use_mmap:1, use_tsched:1;

    pa_rtpoll_item *alsa_rtpoll_item;

    snd_mixer_selem_channel_id_t mixer_map[SND_MIXER_SCHN_LAST];

    pa_smoother *smoother;
    uint64_t read_count;
};

static void userdata_free(struct userdata *u);

static void fix_min_sleep_wakeup(struct userdata *u) {
    size_t max_use, max_use_2;
    pa_assert(u);

    max_use = u->hwbuf_size - u->hwbuf_unused;
    max_use_2 = pa_frame_align(max_use/2, &u->source->sample_spec);

    u->min_sleep = pa_usec_to_bytes(TSCHED_MIN_SLEEP_USEC, &u->source->sample_spec);
    u->min_sleep = PA_CLAMP(u->min_sleep, u->frame_size, max_use_2);

    u->min_wakeup = pa_usec_to_bytes(TSCHED_MIN_WAKEUP_USEC, &u->source->sample_spec);
    u->min_wakeup = PA_CLAMP(u->min_wakeup, u->frame_size, max_use_2);
}

static void fix_tsched_watermark(struct userdata *u) {
    size_t max_use;
    pa_assert(u);

    max_use = u->hwbuf_size - u->hwbuf_unused;

    if (u->tsched_watermark > max_use - u->min_sleep)
        u->tsched_watermark = max_use - u->min_sleep;

    if (u->tsched_watermark < u->min_wakeup)
        u->tsched_watermark = u->min_wakeup;
}

static void adjust_after_overrun(struct userdata *u) {
    size_t old_watermark;
    pa_usec_t old_min_latency, new_min_latency;

    pa_assert(u);

    /* First, just try to increase the watermark */
    old_watermark = u->tsched_watermark;
    u->tsched_watermark *= 2;
    fix_tsched_watermark(u);

    if (old_watermark != u->tsched_watermark) {
        pa_log_notice("Increasing wakeup watermark to %0.2f ms",
                      (double) pa_bytes_to_usec(u->tsched_watermark, &u->source->sample_spec) / PA_USEC_PER_MSEC);
        return;
    }

    /* Hmm, we cannot increase the watermark any further, hence let's raise the latency */
    old_min_latency = u->source->thread_info.min_latency;
    new_min_latency = PA_MIN(old_min_latency * 2, u->source->thread_info.max_latency);

    if (old_min_latency != new_min_latency) {
        pa_log_notice("Increasing minimal latency to %0.2f ms",
                      (double) new_min_latency / PA_USEC_PER_MSEC);

        pa_source_update_latency_range(u->source, new_min_latency, u->source->thread_info.max_latency);
        return;
    }

    /* When we reach this we're officialy fucked! */
}

static pa_usec_t hw_sleep_time(struct userdata *u, pa_usec_t *sleep_usec, pa_usec_t*process_usec) {
    pa_usec_t wm, usec;

    pa_assert(u);

    usec = pa_source_get_requested_latency_within_thread(u->source);

    if (usec == (pa_usec_t) -1)
        usec = pa_bytes_to_usec(u->hwbuf_size, &u->source->sample_spec);

    wm = pa_bytes_to_usec(u->tsched_watermark, &u->source->sample_spec);

    if (wm > usec)
        wm = usec/2;

    *sleep_usec = usec - wm;
    *process_usec = wm;

#ifdef DEBUG_TIMING
    pa_log_debug("Buffer time: %lu ms; Sleep time: %lu ms; Process time: %lu ms",
                 (unsigned long) (usec / PA_USEC_PER_MSEC),
                 (unsigned long) (*sleep_usec / PA_USEC_PER_MSEC),
                 (unsigned long) (*process_usec / PA_USEC_PER_MSEC));
#endif

    return usec;
}

static int try_recover(struct userdata *u, const char *call, int err) {
    pa_assert(u);
    pa_assert(call);
    pa_assert(err < 0);

    pa_log_debug("%s: %s", call, snd_strerror(err));

    pa_assert(err != -EAGAIN);

    if (err == -EPIPE)
        pa_log_debug("%s: Buffer overrun!", call);

    if ((err = snd_pcm_recover(u->pcm_handle, err, 1)) < 0) {
        pa_log("%s: %s", call, snd_strerror(err));
        return -1;
    }

    snd_pcm_start(u->pcm_handle);
    return 0;
}

static size_t check_left_to_record(struct userdata *u, size_t n_bytes) {
    size_t left_to_record;
    size_t rec_space = u->hwbuf_size - u->hwbuf_unused;

    /* We use <= instead of < for this check here because an overrun
     * only happens after the last sample was processed, not already when
     * it is removed from the buffer. This is particularly important
     * when block transfer is used. */

    if (n_bytes <= rec_space) {
        left_to_record = rec_space - n_bytes;

#ifdef DEBUG_TIMING
        pa_log_debug("%0.2f ms left to record", (double) pa_bytes_to_usec(left_to_record, &u->source->sample_spec) / PA_USEC_PER_MSEC);
#endif

    } else {
        left_to_record = 0;

#ifdef DEBUG_TIMING
        PA_DEBUG_TRAP;
#endif

        if (pa_log_ratelimit())
            pa_log_info("Overrun!");

        if (u->use_tsched)
            adjust_after_overrun(u);
    }

    return left_to_record;
}

static int mmap_read(struct userdata *u, pa_usec_t *sleep_usec, pa_bool_t polled) {
    pa_bool_t work_done = FALSE;
    pa_usec_t max_sleep_usec = 0, process_usec = 0;
    size_t left_to_record;

    pa_assert(u);
    pa_source_assert_ref(u->source);

    if (u->use_tsched)
        hw_sleep_time(u, &max_sleep_usec, &process_usec);

    for (;;) {
        snd_pcm_sframes_t n;
        size_t n_bytes;
        int r;

        if (PA_UNLIKELY((n = pa_alsa_safe_avail(u->pcm_handle, u->hwbuf_size, &u->source->sample_spec)) < 0)) {

            if ((r = try_recover(u, "snd_pcm_avail", (int) n)) == 0)
                continue;

            return r;
        }

        n_bytes = (size_t) n * u->frame_size;

#ifdef DEBUG_TIMING
        pa_log_debug("avail: %lu", (unsigned long) n_bytes);
#endif

        left_to_record = check_left_to_record(u, n_bytes);

        if (u->use_tsched)
            if (!polled &&
                pa_bytes_to_usec(left_to_record, &u->source->sample_spec) > process_usec+max_sleep_usec/2) {
#ifdef DEBUG_TIMING
                pa_log_debug("Not reading, because too early.");
#endif
                break;
            }

        if (PA_UNLIKELY(n_bytes <= 0)) {

            if (polled)
                PA_ONCE_BEGIN {
                    char *dn = pa_alsa_get_driver_name_by_pcm(u->pcm_handle);
                    pa_log(_("ALSA woke us up to read new data from the device, but there was actually nothing to read!\n"
                             "Most likely this is a bug in the ALSA driver '%s'. Please report this issue to the ALSA developers.\n"
                             "We were woken up with POLLIN set -- however a subsequent snd_pcm_avail() returned 0 or another value < min_avail."),
                           pa_strnull(dn));
                    pa_xfree(dn);
                } PA_ONCE_END;

#ifdef DEBUG_TIMING
            pa_log_debug("Not reading, because not necessary.");
#endif
            break;
        }

        polled = FALSE;

#ifdef DEBUG_TIMING
        pa_log_debug("Reading");
#endif

        for (;;) {
            int err;
            const snd_pcm_channel_area_t *areas;
            snd_pcm_uframes_t offset, frames;
            pa_memchunk chunk;
            void *p;
            snd_pcm_sframes_t sframes;

            frames = (snd_pcm_uframes_t) (n_bytes / u->frame_size);

/*             pa_log_debug("%lu frames to read", (unsigned long) frames); */

            if (PA_UNLIKELY((err = pa_alsa_safe_mmap_begin(u->pcm_handle, &areas, &offset, &frames, u->hwbuf_size, &u->source->sample_spec)) < 0)) {

                if ((r = try_recover(u, "snd_pcm_mmap_begin", err)) == 0)
                    continue;

                return r;
            }

            /* Make sure that if these memblocks need to be copied they will fit into one slot */
            if (frames > pa_mempool_block_size_max(u->source->core->mempool)/u->frame_size)
                frames = pa_mempool_block_size_max(u->source->core->mempool)/u->frame_size;

            /* Check these are multiples of 8 bit */
            pa_assert((areas[0].first & 7) == 0);
            pa_assert((areas[0].step & 7)== 0);

            /* We assume a single interleaved memory buffer */
            pa_assert((areas[0].first >> 3) == 0);
            pa_assert((areas[0].step >> 3) == u->frame_size);

            p = (uint8_t*) areas[0].addr + (offset * u->frame_size);

            chunk.memblock = pa_memblock_new_fixed(u->core->mempool, p, frames * u->frame_size, TRUE);
            chunk.length = pa_memblock_get_length(chunk.memblock);
            chunk.index = 0;

            pa_source_post(u->source, &chunk);
            pa_memblock_unref_fixed(chunk.memblock);

            if (PA_UNLIKELY((sframes = snd_pcm_mmap_commit(u->pcm_handle, offset, frames)) < 0)) {

                if ((r = try_recover(u, "snd_pcm_mmap_commit", (int) sframes)) == 0)
                    continue;

                return r;
            }

            work_done = TRUE;

            u->read_count += frames * u->frame_size;

#ifdef DEBUG_TIMING
            pa_log_debug("Read %lu bytes", (unsigned long) (frames * u->frame_size));
#endif

            if ((size_t) frames * u->frame_size >= n_bytes)
                break;

            n_bytes -= (size_t) frames * u->frame_size;
        }
    }

    *sleep_usec = pa_bytes_to_usec(left_to_record, &u->source->sample_spec) - process_usec;
    return work_done ? 1 : 0;
}

static int unix_read(struct userdata *u, pa_usec_t *sleep_usec, pa_bool_t polled) {
    int work_done = FALSE;
    pa_usec_t max_sleep_usec = 0, process_usec = 0;
    size_t left_to_record;

    pa_assert(u);
    pa_source_assert_ref(u->source);

    if (u->use_tsched)
        hw_sleep_time(u, &max_sleep_usec, &process_usec);

    for (;;) {
        snd_pcm_sframes_t n;
        size_t n_bytes;
        int r;

        if (PA_UNLIKELY((n = pa_alsa_safe_avail(u->pcm_handle, u->hwbuf_size, &u->source->sample_spec)) < 0)) {

            if ((r = try_recover(u, "snd_pcm_avail", (int) n)) == 0)
                continue;

            return r;
        }

        n_bytes = (size_t) n * u->frame_size;
        left_to_record = check_left_to_record(u, n_bytes);

        if (u->use_tsched)
            if (!polled &&
                pa_bytes_to_usec(left_to_record, &u->source->sample_spec) > process_usec+max_sleep_usec/2)
                break;

        if (PA_UNLIKELY(n_bytes <= 0)) {

            if (polled)
                PA_ONCE_BEGIN {
                    char *dn = pa_alsa_get_driver_name_by_pcm(u->pcm_handle);
                    pa_log(_("ALSA woke us up to read new data from the device, but there was actually nothing to read!\n"
                             "Most likely this is a bug in the ALSA driver '%s'. Please report this issue to the ALSA developers.\n"
                             "We were woken up with POLLIN set -- however a subsequent snd_pcm_avail() returned 0 or another value < min_avail."),
                           pa_strnull(dn));
                    pa_xfree(dn);
                } PA_ONCE_END;

            break;
        }

        polled = FALSE;

        for (;;) {
            void *p;
            snd_pcm_sframes_t frames;
            pa_memchunk chunk;

            chunk.memblock = pa_memblock_new(u->core->mempool, (size_t) -1);

            frames = (snd_pcm_sframes_t) (pa_memblock_get_length(chunk.memblock) / u->frame_size);

            if (frames > (snd_pcm_sframes_t) (n_bytes/u->frame_size))
                frames = (snd_pcm_sframes_t) (n_bytes/u->frame_size);

/*             pa_log_debug("%lu frames to read", (unsigned long) n); */

            p = pa_memblock_acquire(chunk.memblock);
            frames = snd_pcm_readi(u->pcm_handle, (uint8_t*) p, (snd_pcm_uframes_t) frames);
            pa_memblock_release(chunk.memblock);

            pa_assert(frames != 0);

            if (PA_UNLIKELY(frames < 0)) {
                pa_memblock_unref(chunk.memblock);

                if ((r = try_recover(u, "snd_pcm_readi", (int) (frames))) == 0)
                    continue;

                return r;
            }

            chunk.index = 0;
            chunk.length = (size_t) frames * u->frame_size;

            pa_source_post(u->source, &chunk);
            pa_memblock_unref(chunk.memblock);

            work_done = TRUE;

            u->read_count += frames * u->frame_size;

/*             pa_log_debug("read %lu frames", (unsigned long) frames); */

            if ((size_t) frames * u->frame_size >= n_bytes)
                break;

            n_bytes -= (size_t) frames * u->frame_size;
        }
    }

    *sleep_usec = pa_bytes_to_usec(left_to_record, &u->source->sample_spec) - process_usec;
    return work_done ? 1 : 0;
}

static void update_smoother(struct userdata *u) {
    snd_pcm_sframes_t delay = 0;
    uint64_t position;
    int err;
    pa_usec_t now1 = 0, now2;
    snd_pcm_status_t *status;

    snd_pcm_status_alloca(&status);

    pa_assert(u);
    pa_assert(u->pcm_handle);

    /* Let's update the time smoother */

    if (PA_UNLIKELY((err = pa_alsa_safe_delay(u->pcm_handle, &delay, u->hwbuf_size, &u->source->sample_spec)) < 0)) {
        pa_log_warn("Failed to get delay: %s", snd_strerror(err));
        return;
    }

    if (PA_UNLIKELY((err = snd_pcm_status(u->pcm_handle, status)) < 0))
        pa_log_warn("Failed to get timestamp: %s", snd_strerror(err));
    else {
        snd_htimestamp_t htstamp = { 0, 0 };
        snd_pcm_status_get_htstamp(status, &htstamp);
        now1 = pa_timespec_load(&htstamp);
    }

    position = u->read_count + ((uint64_t) delay * (uint64_t) u->frame_size);

    /* Hmm, if the timestamp is 0, then it wasn't set and we take the current time */
    if (now1 <= 0)
        now1 = pa_rtclock_usec();

    now2 = pa_bytes_to_usec(position, &u->source->sample_spec);

    pa_smoother_put(u->smoother, now1, now2);
}

static pa_usec_t source_get_latency(struct userdata *u) {
   int64_t delay;
    pa_usec_t now1, now2;

    pa_assert(u);

    now1 = pa_rtclock_usec();
    now2 = pa_smoother_get(u->smoother, now1);

    delay = (int64_t) now2 - (int64_t) pa_bytes_to_usec(u->read_count, &u->source->sample_spec);

    return delay >= 0 ? (pa_usec_t) delay : 0;
}

static int build_pollfd(struct userdata *u) {
    pa_assert(u);
    pa_assert(u->pcm_handle);

    if (u->alsa_rtpoll_item)
        pa_rtpoll_item_free(u->alsa_rtpoll_item);

    if (!(u->alsa_rtpoll_item = pa_alsa_build_pollfd(u->pcm_handle, u->rtpoll)))
        return -1;

    return 0;
}

static int suspend(struct userdata *u) {
    pa_assert(u);
    pa_assert(u->pcm_handle);

    pa_smoother_pause(u->smoother, pa_rtclock_usec());

    /* Let's suspend */
    snd_pcm_close(u->pcm_handle);
    u->pcm_handle = NULL;

    if (u->alsa_rtpoll_item) {
        pa_rtpoll_item_free(u->alsa_rtpoll_item);
        u->alsa_rtpoll_item = NULL;
    }

    pa_log_info("Device suspended...");

    return 0;
}

static int update_sw_params(struct userdata *u) {
    snd_pcm_uframes_t avail_min;
    int err;

    pa_assert(u);

    /* Use the full buffer if noone asked us for anything specific */
    u->hwbuf_unused = 0;

    if (u->use_tsched) {
        pa_usec_t latency;

        if ((latency = pa_source_get_requested_latency_within_thread(u->source)) != (pa_usec_t) -1) {
            size_t b;

            pa_log_debug("latency set to %0.2fms", (double) latency / PA_USEC_PER_MSEC);

            b = pa_usec_to_bytes(latency, &u->source->sample_spec);

            /* We need at least one sample in our buffer */

            if (PA_UNLIKELY(b < u->frame_size))
                b = u->frame_size;

            u->hwbuf_unused = PA_LIKELY(b < u->hwbuf_size) ? (u->hwbuf_size - b) : 0;
        }

        fix_min_sleep_wakeup(u);
        fix_tsched_watermark(u);
    }

    pa_log_debug("hwbuf_unused=%lu", (unsigned long) u->hwbuf_unused);

    avail_min = 1;

    if (u->use_tsched) {
        pa_usec_t sleep_usec, process_usec;

        hw_sleep_time(u, &sleep_usec, &process_usec);
        avail_min += pa_usec_to_bytes(sleep_usec, &u->source->sample_spec) / u->frame_size;
    }

    pa_log_debug("setting avail_min=%lu", (unsigned long) avail_min);

    if ((err = pa_alsa_set_sw_params(u->pcm_handle, avail_min)) < 0) {
        pa_log("Failed to set software parameters: %s", snd_strerror(err));
        return err;
    }

    return 0;
}

static int unsuspend(struct userdata *u) {
    pa_sample_spec ss;
    int err;
    pa_bool_t b, d;
    unsigned nfrags;
    snd_pcm_uframes_t period_size;

    pa_assert(u);
    pa_assert(!u->pcm_handle);

    pa_log_info("Trying resume...");

    snd_config_update_free_global();

    if ((err = snd_pcm_open(&u->pcm_handle, u->device_name, SND_PCM_STREAM_CAPTURE,
                            /*SND_PCM_NONBLOCK|*/
                            SND_PCM_NO_AUTO_RESAMPLE|
                            SND_PCM_NO_AUTO_CHANNELS|
                            SND_PCM_NO_AUTO_FORMAT)) < 0) {
        pa_log("Error opening PCM device %s: %s", u->device_name, snd_strerror(err));
        goto fail;
    }

    ss = u->source->sample_spec;
    nfrags = u->nfragments;
    period_size = u->fragment_size / u->frame_size;
    b = u->use_mmap;
    d = u->use_tsched;

    if ((err = pa_alsa_set_hw_params(u->pcm_handle, &ss, &nfrags, &period_size, u->hwbuf_size / u->frame_size, &b, &d, TRUE)) < 0) {
        pa_log("Failed to set hardware parameters: %s", snd_strerror(err));
        goto fail;
    }

    if (b != u->use_mmap || d != u->use_tsched) {
        pa_log_warn("Resume failed, couldn't get original access mode.");
        goto fail;
    }

    if (!pa_sample_spec_equal(&ss, &u->source->sample_spec)) {
        pa_log_warn("Resume failed, couldn't restore original sample settings.");
        goto fail;
    }

    if (nfrags != u->nfragments || period_size*u->frame_size != u->fragment_size) {
        pa_log_warn("Resume failed, couldn't restore original fragment settings. (Old: %lu*%lu, New %lu*%lu)",
                    (unsigned long) u->nfragments, (unsigned long) u->fragment_size,
                    (unsigned long) nfrags, period_size * u->frame_size);
        goto fail;
    }

    if (update_sw_params(u) < 0)
        goto fail;

    if (build_pollfd(u) < 0)
        goto fail;

    /* FIXME: We need to reload the volume somehow */

    snd_pcm_start(u->pcm_handle);
    pa_smoother_resume(u->smoother, pa_rtclock_usec());

    pa_log_info("Resumed successfully...");

    return 0;

fail:
    if (u->pcm_handle) {
        snd_pcm_close(u->pcm_handle);
        u->pcm_handle = NULL;
    }

    return -1;
}

static int source_process_msg(pa_msgobject *o, int code, void *data, int64_t offset, pa_memchunk *chunk) {
    struct userdata *u = PA_SOURCE(o)->userdata;

    switch (code) {

        case PA_SOURCE_MESSAGE_GET_LATENCY: {
            pa_usec_t r = 0;

            if (u->pcm_handle)
                r = source_get_latency(u);

            *((pa_usec_t*) data) = r;

            return 0;
        }

        case PA_SOURCE_MESSAGE_SET_STATE:

            switch ((pa_source_state_t) PA_PTR_TO_UINT(data)) {

                case PA_SOURCE_SUSPENDED:
                    pa_assert(PA_SOURCE_IS_OPENED(u->source->thread_info.state));

                    if (suspend(u) < 0)
                        return -1;

                    break;

                case PA_SOURCE_IDLE:
                case PA_SOURCE_RUNNING:

                    if (u->source->thread_info.state == PA_SOURCE_INIT) {
                        if (build_pollfd(u) < 0)
                            return -1;

                        snd_pcm_start(u->pcm_handle);
                    }

                    if (u->source->thread_info.state == PA_SOURCE_SUSPENDED) {
                        if (unsuspend(u) < 0)
                            return -1;
                    }

                    break;

                case PA_SOURCE_UNLINKED:
                case PA_SOURCE_INIT:
                case PA_SOURCE_INVALID_STATE:
                    ;
            }

            break;
    }

    return pa_source_process_msg(o, code, data, offset, chunk);
}

static int mixer_callback(snd_mixer_elem_t *elem, unsigned int mask) {
    struct userdata *u = snd_mixer_elem_get_callback_private(elem);

    pa_assert(u);
    pa_assert(u->mixer_handle);

    if (mask == SND_CTL_EVENT_MASK_REMOVE)
        return 0;

    if (mask & SND_CTL_EVENT_MASK_VALUE) {
        pa_source_get_volume(u->source, TRUE);
        pa_source_get_mute(u->source, TRUE);
    }

    return 0;
}

static pa_volume_t from_alsa_volume(struct userdata *u, long alsa_vol) {

    return (pa_volume_t) round(((double) (alsa_vol - u->hw_volume_min) * PA_VOLUME_NORM) /
                               (double) (u->hw_volume_max - u->hw_volume_min));
}

static long to_alsa_volume(struct userdata *u, pa_volume_t vol) {
    long alsa_vol;

    alsa_vol = (long) round(((double) vol * (double) (u->hw_volume_max - u->hw_volume_min))
                            / PA_VOLUME_NORM) + u->hw_volume_min;

    return PA_CLAMP_UNLIKELY(alsa_vol, u->hw_volume_min, u->hw_volume_max);
}

static void source_get_volume_cb(pa_source *s) {
    struct userdata *u = s->userdata;
    int err;
    unsigned i;
    pa_cvolume r;
    char t[PA_CVOLUME_SNPRINT_MAX];

    pa_assert(u);
    pa_assert(u->mixer_elem);

    if (u->mixer_seperate_channels) {

        r.channels = s->sample_spec.channels;

        for (i = 0; i < s->sample_spec.channels; i++) {
            long alsa_vol;

            if (u->hw_dB_supported) {

                if ((err = snd_mixer_selem_get_capture_dB(u->mixer_elem, u->mixer_map[i], &alsa_vol)) < 0)
                    goto fail;

#ifdef HAVE_VALGRIND_MEMCHECK_H
                VALGRIND_MAKE_MEM_DEFINED(&alsa_vol, sizeof(alsa_vol));
#endif

                r.values[i] = pa_sw_volume_from_dB((double) (alsa_vol - u->hw_dB_max) / 100.0);
            } else {

                if ((err = snd_mixer_selem_get_capture_volume(u->mixer_elem, u->mixer_map[i], &alsa_vol)) < 0)
                    goto fail;

                r.values[i] = from_alsa_volume(u, alsa_vol);
            }
        }

    } else {
        long alsa_vol;

        if (u->hw_dB_supported) {

            if ((err = snd_mixer_selem_get_capture_dB(u->mixer_elem, SND_MIXER_SCHN_MONO, &alsa_vol)) < 0)
                goto fail;

#ifdef HAVE_VALGRIND_MEMCHECK_H
            VALGRIND_MAKE_MEM_DEFINED(&alsa_vol, sizeof(alsa_vol));
#endif

            pa_cvolume_set(&r, s->sample_spec.channels, pa_sw_volume_from_dB((double) (alsa_vol - u->hw_dB_max) / 100.0));

        } else {

            if ((err = snd_mixer_selem_get_capture_volume(u->mixer_elem, SND_MIXER_SCHN_MONO, &alsa_vol)) < 0)
                goto fail;

            pa_cvolume_set(&r, s->sample_spec.channels, from_alsa_volume(u, alsa_vol));
        }
    }

    pa_log_debug("Read hardware volume: %s", pa_cvolume_snprint(t, sizeof(t), &r));

    if (!pa_cvolume_equal(&u->hardware_volume, &r)) {

        s->virtual_volume = u->hardware_volume = r;

        if (u->hw_dB_supported) {
            pa_cvolume reset;

            /* Hmm, so the hardware volume changed, let's reset our software volume */
            pa_cvolume_reset(&reset, s->sample_spec.channels);
            pa_source_set_soft_volume(s, &reset);
        }
    }

    return;

fail:
    pa_log_error("Unable to read volume: %s", snd_strerror(err));
}

static void source_set_volume_cb(pa_source *s) {
    struct userdata *u = s->userdata;
    int err;
    unsigned i;
    pa_cvolume r;

    pa_assert(u);
    pa_assert(u->mixer_elem);

    if (u->mixer_seperate_channels) {

        r.channels = s->sample_spec.channels;

        for (i = 0; i < s->sample_spec.channels; i++) {
            long alsa_vol;
            pa_volume_t vol;

            vol = s->virtual_volume.values[i];

            if (u->hw_dB_supported) {

                alsa_vol = (long) (pa_sw_volume_to_dB(vol) * 100);
                alsa_vol += u->hw_dB_max;
                alsa_vol = PA_CLAMP_UNLIKELY(alsa_vol, u->hw_dB_min, u->hw_dB_max);

                if ((err = snd_mixer_selem_set_capture_dB(u->mixer_elem, u->mixer_map[i], alsa_vol, 1)) < 0)
                    goto fail;

                if ((err = snd_mixer_selem_get_capture_dB(u->mixer_elem, u->mixer_map[i], &alsa_vol)) < 0)
                    goto fail;

#ifdef HAVE_VALGRIND_MEMCHECK_H
                VALGRIND_MAKE_MEM_DEFINED(&alsa_vol, sizeof(alsa_vol));
#endif

                r.values[i] = pa_sw_volume_from_dB((double) (alsa_vol - u->hw_dB_max) / 100.0);

            } else {
                alsa_vol = to_alsa_volume(u, vol);

                if ((err = snd_mixer_selem_set_capture_volume(u->mixer_elem, u->mixer_map[i], alsa_vol)) < 0)
                    goto fail;

                if ((err = snd_mixer_selem_get_capture_volume(u->mixer_elem, u->mixer_map[i], &alsa_vol)) < 0)
                    goto fail;

                r.values[i] = from_alsa_volume(u, alsa_vol);
            }
        }

    } else {
        pa_volume_t vol;
        long alsa_vol;

        vol = pa_cvolume_max(&s->virtual_volume);

        if (u->hw_dB_supported) {
            alsa_vol = (long) (pa_sw_volume_to_dB(vol) * 100);
            alsa_vol += u->hw_dB_max;
            alsa_vol = PA_CLAMP_UNLIKELY(alsa_vol, u->hw_dB_min, u->hw_dB_max);

            if ((err = snd_mixer_selem_set_capture_dB_all(u->mixer_elem, alsa_vol, 1)) < 0)
                goto fail;

            if ((err = snd_mixer_selem_get_capture_dB(u->mixer_elem, SND_MIXER_SCHN_MONO, &alsa_vol)) < 0)
                goto fail;

#ifdef HAVE_VALGRIND_MEMCHECK_H
            VALGRIND_MAKE_MEM_DEFINED(&alsa_vol, sizeof(alsa_vol));
#endif

            pa_cvolume_set(&r, s->sample_spec.channels, pa_sw_volume_from_dB((double) (alsa_vol - u->hw_dB_max) / 100.0));

        } else {
            alsa_vol = to_alsa_volume(u, vol);

            if ((err = snd_mixer_selem_set_capture_volume_all(u->mixer_elem, alsa_vol)) < 0)
                goto fail;

            if ((err = snd_mixer_selem_get_capture_volume(u->mixer_elem, SND_MIXER_SCHN_MONO, &alsa_vol)) < 0)
                goto fail;

            pa_cvolume_set(&r, s->sample_spec.channels, from_alsa_volume(u, alsa_vol));
        }
    }

    u->hardware_volume = r;

    if (u->hw_dB_supported) {
        char t[PA_CVOLUME_SNPRINT_MAX];

        /* Match exactly what the user requested by software */

        pa_sw_cvolume_divide(&s->soft_volume, &s->virtual_volume, &u->hardware_volume);

        pa_log_debug("Requested volume: %s", pa_cvolume_snprint(t, sizeof(t), &s->virtual_volume));
        pa_log_debug("Got hardware volume: %s", pa_cvolume_snprint(t, sizeof(t), &u->hardware_volume));
        pa_log_debug("Calculated software volume: %s", pa_cvolume_snprint(t, sizeof(t), &s->soft_volume));

    } else

        /* We can't match exactly what the user requested, hence let's
         * at least tell the user about it */

        s->virtual_volume = r;

    return;

fail:
    pa_log_error("Unable to set volume: %s", snd_strerror(err));
}

static void source_get_mute_cb(pa_source *s) {
    struct userdata *u = s->userdata;
    int err, sw;

    pa_assert(u);
    pa_assert(u->mixer_elem);

    if ((err = snd_mixer_selem_get_capture_switch(u->mixer_elem, 0, &sw)) < 0) {
        pa_log_error("Unable to get switch: %s", snd_strerror(err));
        return;
    }

    s->muted = !sw;
}

static void source_set_mute_cb(pa_source *s) {
    struct userdata *u = s->userdata;
    int err;

    pa_assert(u);
    pa_assert(u->mixer_elem);

    if ((err = snd_mixer_selem_set_capture_switch_all(u->mixer_elem, !s->muted)) < 0) {
        pa_log_error("Unable to set switch: %s", snd_strerror(err));
        return;
    }
}

static void source_update_requested_latency_cb(pa_source *s) {
    struct userdata *u = s->userdata;
    pa_assert(u);

    if (!u->pcm_handle)
        return;

    update_sw_params(u);
}

static void thread_func(void *userdata) {
    struct userdata *u = userdata;
    unsigned short revents = 0;

    pa_assert(u);

    pa_log_debug("Thread starting up");

    if (u->core->realtime_scheduling)
        pa_make_realtime(u->core->realtime_priority);

    pa_thread_mq_install(&u->thread_mq);
    pa_rtpoll_install(u->rtpoll);

    for (;;) {
        int ret;

#ifdef DEBUG_TIMING
        pa_log_debug("Loop");
#endif

        /* Read some data and pass it to the sources */
        if (PA_SOURCE_IS_OPENED(u->source->thread_info.state)) {
            int work_done;
            pa_usec_t sleep_usec = 0;

            if (u->use_mmap)
                work_done = mmap_read(u, &sleep_usec, revents & POLLIN);
            else
                work_done = unix_read(u, &sleep_usec, revents & POLLIN);

            if (work_done < 0)
                goto fail;

/*             pa_log_debug("work_done = %i", work_done); */

            if (work_done)
                update_smoother(u);

            if (u->use_tsched) {
                pa_usec_t cusec;

                /* OK, the capture buffer is now empty, let's
                 * calculate when to wake up next */

/*                 pa_log_debug("Waking up in %0.2fms (sound card clock).", (double) sleep_usec / PA_USEC_PER_MSEC); */

                /* Convert from the sound card time domain to the
                 * system time domain */
                cusec = pa_smoother_translate(u->smoother, pa_rtclock_usec(), sleep_usec);

/*                 pa_log_debug("Waking up in %0.2fms (system clock).", (double) cusec / PA_USEC_PER_MSEC); */

                /* We don't trust the conversion, so we wake up whatever comes first */
                pa_rtpoll_set_timer_relative(u->rtpoll, PA_MIN(sleep_usec, cusec));
            }
        } else if (u->use_tsched)

            /* OK, we're in an invalid state, let's disable our timers */
            pa_rtpoll_set_timer_disabled(u->rtpoll);

        /* Hmm, nothing to do. Let's sleep */
        if ((ret = pa_rtpoll_run(u->rtpoll, TRUE)) < 0)
            goto fail;

        if (ret == 0)
            goto finish;

        /* Tell ALSA about this and process its response */
        if (PA_SOURCE_IS_OPENED(u->source->thread_info.state)) {
            struct pollfd *pollfd;
            int err;
            unsigned n;

            pollfd = pa_rtpoll_item_get_pollfd(u->alsa_rtpoll_item, &n);

            if ((err = snd_pcm_poll_descriptors_revents(u->pcm_handle, pollfd, n, &revents)) < 0) {
                pa_log("snd_pcm_poll_descriptors_revents() failed: %s", snd_strerror(err));
                goto fail;
            }

            if (revents & ~POLLIN) {
                if (pa_alsa_recover_from_poll(u->pcm_handle, revents) < 0)
                    goto fail;

                snd_pcm_start(u->pcm_handle);
            } else if (revents && u->use_tsched && pa_log_ratelimit())
                pa_log_debug("Wakeup from ALSA!");

        } else
            revents = 0;
    }

fail:
    /* If this was no regular exit from the loop we have to continue
     * processing messages until we received PA_MESSAGE_SHUTDOWN */
    pa_asyncmsgq_post(u->thread_mq.outq, PA_MSGOBJECT(u->core), PA_CORE_MESSAGE_UNLOAD_MODULE, u->module, 0, NULL, NULL);
    pa_asyncmsgq_wait_for(u->thread_mq.inq, PA_MESSAGE_SHUTDOWN);

finish:
    pa_log_debug("Thread shutting down");
}

static void set_source_name(pa_source_new_data *data, pa_modargs *ma, const char *device_id, const char *device_name) {
    const char *n;
    char *t;

    pa_assert(data);
    pa_assert(ma);
    pa_assert(device_name);

    if ((n = pa_modargs_get_value(ma, "source_name", NULL))) {
        pa_source_new_data_set_name(data, n);
        data->namereg_fail = TRUE;
        return;
    }

    if ((n = pa_modargs_get_value(ma, "name", NULL)))
        data->namereg_fail = TRUE;
    else {
        n = device_id ? device_id : device_name;
        data->namereg_fail = FALSE;
    }

    t = pa_sprintf_malloc("alsa_input.%s", n);
    pa_source_new_data_set_name(data, t);
    pa_xfree(t);
}

static int setup_mixer(struct userdata *u, pa_bool_t ignore_dB) {
    pa_assert(u);

    if (!u->mixer_handle)
        return 0;

    pa_assert(u->mixer_elem);

    if (snd_mixer_selem_has_capture_volume(u->mixer_elem)) {
        pa_bool_t suitable = FALSE;

        if (snd_mixer_selem_get_capture_volume_range(u->mixer_elem, &u->hw_volume_min, &u->hw_volume_max) < 0)
            pa_log_info("Failed to get volume range. Falling back to software volume control.");
        else if (u->hw_volume_min >= u->hw_volume_max)
            pa_log_warn("Your kernel driver is broken: it reports a volume range from %li to %li which makes no sense.", u->hw_volume_min, u->hw_volume_max);
        else {
            pa_log_info("Volume ranges from %li to %li.", u->hw_volume_min, u->hw_volume_max);
            suitable = TRUE;
        }

        if (suitable) {
            if (ignore_dB || snd_mixer_selem_get_capture_dB_range(u->mixer_elem, &u->hw_dB_min, &u->hw_dB_max) < 0)
                pa_log_info("Mixer doesn't support dB information or data is ignored.");
            else {
#ifdef HAVE_VALGRIND_MEMCHECK_H
                VALGRIND_MAKE_MEM_DEFINED(&u->hw_dB_min, sizeof(u->hw_dB_min));
                VALGRIND_MAKE_MEM_DEFINED(&u->hw_dB_max, sizeof(u->hw_dB_max));
#endif

                if (u->hw_dB_min >= u->hw_dB_max)
                    pa_log_warn("Your kernel driver is broken: it reports a volume range from %0.2f dB to %0.2f dB which makes no sense.", (double) u->hw_dB_min/100.0, (double) u->hw_dB_max/100.0);
                else {
                    pa_log_info("Volume ranges from %0.2f dB to %0.2f dB.", (double) u->hw_dB_min/100.0, (double) u->hw_dB_max/100.0);
                    u->hw_dB_supported = TRUE;

                    if (u->hw_dB_max > 0) {
                        u->source->base_volume = pa_sw_volume_from_dB(- (double) u->hw_dB_max/100.0);
                        pa_log_info("Fixing base volume to %0.2f dB", pa_sw_volume_to_dB(u->source->base_volume));
                    } else
                        pa_log_info("No particular base volume set, fixing to 0 dB");
                }
            }

            if (!u->hw_dB_supported &&
                u->hw_volume_max - u->hw_volume_min < 3) {

                pa_log_info("Device has less than 4 volume levels. Falling back to software volume control.");
                suitable = FALSE;
            }
        }

        if (suitable) {
            u->mixer_seperate_channels = pa_alsa_calc_mixer_map(u->mixer_elem, &u->source->channel_map, u->mixer_map, FALSE) >= 0;

            u->source->get_volume = source_get_volume_cb;
            u->source->set_volume = source_set_volume_cb;
            u->source->flags |= PA_SOURCE_HW_VOLUME_CTRL | (u->hw_dB_supported ? PA_SOURCE_DECIBEL_VOLUME : 0);
            pa_log_info("Using hardware volume control. Hardware dB scale %s.", u->hw_dB_supported ? "supported" : "not supported");

            if (!u->hw_dB_supported)
                u->source->n_volume_steps = u->hw_volume_max - u->hw_volume_min + 1;
        } else
            pa_log_info("Using software volume control.");
    }

    if (snd_mixer_selem_has_capture_switch(u->mixer_elem)) {
        u->source->get_mute = source_get_mute_cb;
        u->source->set_mute = source_set_mute_cb;
        u->source->flags |= PA_SOURCE_HW_MUTE_CTRL;
    } else
        pa_log_info("Using software mute control.");

    u->mixer_fdl = pa_alsa_fdlist_new();

    if (pa_alsa_fdlist_set_mixer(u->mixer_fdl, u->mixer_handle, u->core->mainloop) < 0) {
        pa_log("Failed to initialize file descriptor monitoring");
        return -1;
    }

    snd_mixer_elem_set_callback(u->mixer_elem, mixer_callback);
    snd_mixer_elem_set_callback_private(u->mixer_elem, u);

    return 0;
}

pa_source *pa_alsa_source_new(pa_module *m, pa_modargs *ma, const char*driver, pa_card *card, const pa_alsa_profile_info *profile) {

    struct userdata *u = NULL;
    const char *dev_id = NULL;
    pa_sample_spec ss;
    pa_channel_map map;
    uint32_t nfrags, hwbuf_size, frag_size, tsched_size, tsched_watermark;
    snd_pcm_uframes_t period_frames, tsched_frames;
    size_t frame_size;
    pa_bool_t use_mmap = TRUE, b, use_tsched = TRUE, d, ignore_dB = FALSE;
    pa_source_new_data data;

    pa_assert(m);
    pa_assert(ma);

    ss = m->core->default_sample_spec;
    map = m->core->default_channel_map;
    if (pa_modargs_get_sample_spec_and_channel_map(ma, &ss, &map, PA_CHANNEL_MAP_ALSA) < 0) {
        pa_log("Failed to parse sample specification");
        goto fail;
    }

    frame_size = pa_frame_size(&ss);

    nfrags = m->core->default_n_fragments;
    frag_size = (uint32_t) pa_usec_to_bytes(m->core->default_fragment_size_msec*PA_USEC_PER_MSEC, &ss);
    if (frag_size <= 0)
        frag_size = (uint32_t) frame_size;
    tsched_size = (uint32_t) pa_usec_to_bytes(DEFAULT_TSCHED_BUFFER_USEC, &ss);
    tsched_watermark = (uint32_t) pa_usec_to_bytes(DEFAULT_TSCHED_WATERMARK_USEC, &ss);

    if (pa_modargs_get_value_u32(ma, "fragments", &nfrags) < 0 ||
        pa_modargs_get_value_u32(ma, "fragment_size", &frag_size) < 0 ||
        pa_modargs_get_value_u32(ma, "tsched_buffer_size", &tsched_size) < 0 ||
        pa_modargs_get_value_u32(ma, "tsched_buffer_watermark", &tsched_watermark) < 0) {
        pa_log("Failed to parse buffer metrics");
        goto fail;
    }

    hwbuf_size = frag_size * nfrags;
    period_frames = frag_size/frame_size;
    tsched_frames = tsched_size/frame_size;

    if (pa_modargs_get_value_boolean(ma, "mmap", &use_mmap) < 0) {
        pa_log("Failed to parse mmap argument.");
        goto fail;
    }

    if (pa_modargs_get_value_boolean(ma, "tsched", &use_tsched) < 0) {
        pa_log("Failed to parse timer_scheduling argument.");
        goto fail;
    }

    if (pa_modargs_get_value_boolean(ma, "ignore_dB", &ignore_dB) < 0) {
        pa_log("Failed to parse ignore_dB argument.");
        goto fail;
    }

    if (use_tsched && !pa_rtclock_hrtimer()) {
        pa_log_notice("Disabling timer-based scheduling because high-resolution timers are not available from the kernel.");
        use_tsched = FALSE;
    }

    u = pa_xnew0(struct userdata, 1);
    u->core = m->core;
    u->module = m;
    u->use_mmap = use_mmap;
    u->use_tsched = use_tsched;
    u->rtpoll = pa_rtpoll_new();
    pa_thread_mq_init(&u->thread_mq, m->core->mainloop, u->rtpoll);
    u->alsa_rtpoll_item = NULL;

    u->smoother = pa_smoother_new(DEFAULT_TSCHED_WATERMARK_USEC*2, DEFAULT_TSCHED_WATERMARK_USEC*2, TRUE, 5);
    pa_smoother_set_time_offset(u->smoother, pa_rtclock_usec());

    b = use_mmap;
    d = use_tsched;

    if (profile) {

        if (!(dev_id = pa_modargs_get_value(ma, "device_id", NULL))) {
            pa_log("device_id= not set");
            goto fail;
        }

        if (!(u->pcm_handle = pa_alsa_open_by_device_id_profile(
                      dev_id,
                      &u->device_name,
                      &ss, &map,
                      SND_PCM_STREAM_CAPTURE,
                      &nfrags, &period_frames, tsched_frames,
                      &b, &d, profile)))
            goto fail;

    } else if ((dev_id = pa_modargs_get_value(ma, "device_id", NULL))) {

        if (!(u->pcm_handle = pa_alsa_open_by_device_id_auto(
                      dev_id,
                      &u->device_name,
                      &ss, &map,
                      SND_PCM_STREAM_CAPTURE,
                      &nfrags, &period_frames, tsched_frames,
                      &b, &d, &profile)))
            goto fail;

    } else {

        if (!(u->pcm_handle = pa_alsa_open_by_device_string(
                      pa_modargs_get_value(ma, "device", DEFAULT_DEVICE),
                      &u->device_name,
                      &ss, &map,
                      SND_PCM_STREAM_CAPTURE,
                      &nfrags, &period_frames, tsched_frames,
                      &b, &d, FALSE)))
            goto fail;
    }

    pa_assert(u->device_name);
    pa_log_info("Successfully opened device %s.", u->device_name);

    if (profile)
        pa_log_info("Selected configuration '%s' (%s).", profile->description, profile->name);

    if (use_mmap && !b) {
        pa_log_info("Device doesn't support mmap(), falling back to UNIX read/write mode.");
        u->use_mmap = use_mmap = FALSE;
    }

    if (use_tsched && (!b || !d)) {
        pa_log_info("Cannot enable timer-based scheduling, falling back to sound IRQ scheduling.");
        u->use_tsched = use_tsched = FALSE;
    }

    if (u->use_mmap)
        pa_log_info("Successfully enabled mmap() mode.");

    if (u->use_tsched)
        pa_log_info("Successfully enabled timer-based scheduling mode.");

    /* ALSA might tweak the sample spec, so recalculate the frame size */
    frame_size = pa_frame_size(&ss);

    pa_alsa_find_mixer_and_elem(u->pcm_handle, &u->mixer_handle, &u->mixer_elem);

    pa_source_new_data_init(&data);
    data.driver = driver;
    data.module = m;
    data.card = card;
    set_source_name(&data, ma, dev_id, u->device_name);
    pa_source_new_data_set_sample_spec(&data, &ss);
    pa_source_new_data_set_channel_map(&data, &map);

    pa_alsa_init_proplist_pcm(m->core, data.proplist, u->pcm_handle);
    pa_proplist_sets(data.proplist, PA_PROP_DEVICE_STRING, u->device_name);
    pa_proplist_setf(data.proplist, PA_PROP_DEVICE_BUFFERING_BUFFER_SIZE, "%lu", (unsigned long) (period_frames * frame_size * nfrags));
    pa_proplist_setf(data.proplist, PA_PROP_DEVICE_BUFFERING_FRAGMENT_SIZE, "%lu", (unsigned long) (period_frames * frame_size));
    pa_proplist_sets(data.proplist, PA_PROP_DEVICE_ACCESS_MODE, u->use_tsched ? "mmap+timer" : (u->use_mmap ? "mmap" : "serial"));

    if (profile) {
        pa_proplist_sets(data.proplist, PA_PROP_DEVICE_PROFILE_NAME, profile->name);
        pa_proplist_sets(data.proplist, PA_PROP_DEVICE_PROFILE_DESCRIPTION, profile->description);
    }

    u->source = pa_source_new(m->core, &data, PA_SOURCE_HARDWARE|PA_SOURCE_LATENCY);
    pa_source_new_data_done(&data);

    if (!u->source) {
        pa_log("Failed to create source object");
        goto fail;
    }

    u->source->parent.process_msg = source_process_msg;
    u->source->update_requested_latency = source_update_requested_latency_cb;
    u->source->userdata = u;

    pa_source_set_asyncmsgq(u->source, u->thread_mq.inq);
    pa_source_set_rtpoll(u->source, u->rtpoll);

    u->frame_size = frame_size;
    u->fragment_size = frag_size = (uint32_t) (period_frames * frame_size);
    u->nfragments = nfrags;
    u->hwbuf_size = u->fragment_size * nfrags;
    u->tsched_watermark = tsched_watermark;
    pa_cvolume_mute(&u->hardware_volume, u->source->sample_spec.channels);

    if (use_tsched) {
        fix_min_sleep_wakeup(u);
        fix_tsched_watermark(u);
    }

    pa_source_set_latency_range(u->source,
                                !use_tsched ? pa_bytes_to_usec(u->hwbuf_size, &ss) : (pa_usec_t) -1,
                                pa_bytes_to_usec(u->hwbuf_size, &ss));

    pa_log_info("Using %u fragments of size %lu bytes, buffer time is %0.2fms",
                nfrags, (long unsigned) u->fragment_size,
                (double) pa_bytes_to_usec(u->hwbuf_size, &ss) / PA_USEC_PER_MSEC);

    if (use_tsched)
        pa_log_info("Time scheduling watermark is %0.2fms",
                    (double) pa_bytes_to_usec(u->tsched_watermark, &ss) / PA_USEC_PER_MSEC);

    if (update_sw_params(u) < 0)
        goto fail;

    if (setup_mixer(u, ignore_dB) < 0)
        goto fail;

    pa_alsa_dump(u->pcm_handle);

    if (!(u->thread = pa_thread_new(thread_func, u))) {
        pa_log("Failed to create thread.");
        goto fail;
    }
    /* Get initial mixer settings */
    if (data.volume_is_set) {
        if (u->source->set_volume)
            u->source->set_volume(u->source);
    } else {
        if (u->source->get_volume)
            u->source->get_volume(u->source);
    }

    if (data.muted_is_set) {
        if (u->source->set_mute)
            u->source->set_mute(u->source);
    } else {
        if (u->source->get_mute)
            u->source->get_mute(u->source);
    }

    pa_source_put(u->source);

    return u->source;

fail:

    userdata_free(u);

    return NULL;
}

static void userdata_free(struct userdata *u) {
    pa_assert(u);

    if (u->source)
        pa_source_unlink(u->source);

    if (u->thread) {
        pa_asyncmsgq_send(u->thread_mq.inq, NULL, PA_MESSAGE_SHUTDOWN, NULL, 0, NULL);
        pa_thread_free(u->thread);
    }

    pa_thread_mq_done(&u->thread_mq);

    if (u->source)
        pa_source_unref(u->source);

    if (u->alsa_rtpoll_item)
        pa_rtpoll_item_free(u->alsa_rtpoll_item);

    if (u->rtpoll)
        pa_rtpoll_free(u->rtpoll);

    if (u->mixer_fdl)
        pa_alsa_fdlist_free(u->mixer_fdl);

    if (u->mixer_handle)
        snd_mixer_close(u->mixer_handle);

    if (u->pcm_handle) {
        snd_pcm_drop(u->pcm_handle);
        snd_pcm_close(u->pcm_handle);
    }

    if (u->smoother)
        pa_smoother_free(u->smoother);

    pa_xfree(u->device_name);
    pa_xfree(u);
}

void pa_alsa_source_free(pa_source *s) {
    struct userdata *u;

    pa_source_assert_ref(s);
    pa_assert_se(u = s->userdata);

    userdata_free(u);
}