pulseaudio/src/modules/alsa/module-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 <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 "module-alsa-source-symdef.h"

PA_MODULE_AUTHOR("Lennart Poettering");
PA_MODULE_DESCRIPTION("ALSA Source");
PA_MODULE_VERSION(PACKAGE_VERSION);
PA_MODULE_LOAD_ONCE(FALSE);
PA_MODULE_USAGE(
        "source_name=<name for the source> "
        "device=<ALSA device> "
        "device_id=<ALSA card index> "
        "format=<sample format> "
        "rate=<sample rate> "
        "channels=<number of channels> "
        "channel_map=<channel map> "
        "fragments=<number of fragments> "
        "fragment_size=<fragment size> "
        "mmap=<enable memory mapping?> "
        "tsched=<enable system timer based scheduling mode?> "
        "tsched_buffer_size=<buffer size when using timer based scheduling> "
        "tsched_buffer_watermark=<upper fill watermark>");

static const char* const valid_modargs[] = {
    "source_name",
    "device",
    "device_id",
    "format",
    "rate",
    "channels",
    "channel_map",
    "fragments",
    "fragment_size",
    "mmap",
    "tsched",
    "tsched_buffer_size",
    "tsched_buffer_watermark",
    NULL
};

#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 (3*PA_USEC_PER_MSEC)           /* 3ms */
#define TSCHED_MIN_WAKEUP_USEC (3*PA_USEC_PER_MSEC)          /* 3ms */

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;
    pa_bool_t mixer_seperate_channels;

    pa_cvolume hardware_volume;

    size_t frame_size, fragment_size, hwbuf_size, tsched_watermark;
    unsigned nfragments;

    char *device_name;

    pa_bool_t use_mmap, use_tsched;

    pa_rtpoll_item *alsa_rtpoll_item;

    snd_mixer_selem_channel_id_t mixer_map[SND_MIXER_SCHN_LAST];

    pa_smoother *smoother;
    int64_t frame_index;

    snd_pcm_sframes_t hwbuf_unused_frames;
};

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

    max_use = u->hwbuf_size - (size_t) u->hwbuf_unused_frames * u->frame_size;

    min_sleep = pa_usec_to_bytes(TSCHED_MIN_SLEEP_USEC, &u->source->sample_spec);
    min_wakeup = pa_usec_to_bytes(TSCHED_MIN_WAKEUP_USEC, &u->source->sample_spec);

    if (min_sleep > max_use/2)
        min_sleep = pa_frame_align(max_use/2, &u->source->sample_spec);
    if (min_sleep < u->frame_size)
        min_sleep = u->frame_size;

    if (min_wakeup > max_use/2)
        min_wakeup = pa_frame_align(max_use/2, &u->source->sample_spec);
    if (min_wakeup < u->frame_size)
        min_wakeup = u->frame_size;

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

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

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);

/*     pa_log_debug("hw buffer time: %u ms", (unsigned) (usec / PA_USEC_PER_MSEC)); */

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

    if (usec >= wm) {
        *sleep_usec = usec - wm;
        *process_usec = wm;
    } else
        *process_usec = *sleep_usec = usec /= 2;

/*     pa_log_debug("after watermark: %u ms", (unsigned) (*sleep_usec / PA_USEC_PER_MSEC)); */

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

    pa_log("%s: %s", call, snd_strerror(err));
    return -1;
}

static size_t check_left_to_record(struct userdata *u, snd_pcm_sframes_t n) {
    size_t left_to_record;
    size_t rec_space = u->hwbuf_size - (size_t) u->hwbuf_unused_frames*u->frame_size;

    if ((size_t) n*u->frame_size < rec_space)
        left_to_record = rec_space - ((size_t) n*u->frame_size);
    else
        left_to_record = 0;

    if (left_to_record > 0) {
/*         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); */
    } else {
        pa_log_info("Overrun!");

        if (u->use_tsched) {
            size_t 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 left_to_record;
}

static int mmap_read(struct userdata *u, pa_usec_t *sleep_usec, pa_bool_t polled) {
    int work_done = 0;
    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;
        int r;

        snd_pcm_hwsync(u->pcm_handle);

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

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

            return r;
        }

        left_to_record = check_left_to_record(u, n);

        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 <= 0)) {

            if (polled)
                pa_log("ALSA woke us up to read new data from the device, but there was actually nothing to read! "
                       "Most likely this is an ALSA driver bug. Please report this issue to the ALSA developers. "
                       "We were woken up with POLLIN set -- however a subsequent snd_pcm_avail_update() returned 0.");

            break;
        }

        polled = FALSE;

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

/*             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 = 1;

            u->frame_index += (int64_t) frames;

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

            if (frames >= (snd_pcm_uframes_t) n)
                break;

            n -= (snd_pcm_sframes_t) frames;
        }
    }

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

static int unix_read(struct userdata *u, pa_usec_t *sleep_usec, pa_bool_t polled) {
    int work_done = 0;
    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;
        int r;

        snd_pcm_hwsync(u->pcm_handle);

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

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

            return r;
        }

        left_to_record = check_left_to_record(u, n);

        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 <= 0)) {

            if (polled)
                pa_log("ALSA woke us up to read new data from the device, but there was actually nothing to read! "
                       "Most likely this is an ALSA driver bug. Please report this issue to the ALSA developers. "
                       "We were woken up with POLLIN set -- however a subsequent snd_pcm_avail_update() returned 0.");

            return work_done;
        }

        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 > n)
                frames = n;

/*             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 = 1;

            u->frame_index += frames;

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

            if (frames >= n)
                break;

            n -= frames;
        }
    }

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

static void update_smoother(struct userdata *u) {
    snd_pcm_sframes_t delay = 0;
    int64_t frames;
    int err;
    pa_usec_t now1, now2;

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

    /* Let's update the time smoother */

    snd_pcm_hwsync(u->pcm_handle);
    snd_pcm_avail_update(u->pcm_handle);

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

    frames = u->frame_index + delay;

    now1 = pa_rtclock_usec();
    now2 = pa_bytes_to_usec((uint64_t) frames * u->frame_size, &u->source->sample_spec);

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

static pa_usec_t source_get_latency(struct userdata *u) {
    pa_usec_t r = 0;
    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((uint64_t) u->frame_index * u->frame_size, &u->source->sample_spec);

    if (delay > 0)
        r = (pa_usec_t) delay;

    return r;
}

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_frames = 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_frames = (snd_pcm_sframes_t)
                (PA_LIKELY(b < u->hwbuf_size) ?
                 ((u->hwbuf_size - b) / u->frame_size) : 0);
        }

        fix_tsched_watermark(u);
    }

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

    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:
                    ;
            }

            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 int 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)) {

        u->hardware_volume = s->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 0;

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

    return -1;
}

static int 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->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;

                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->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;

            pa_cvolume_set(&r, s->volume.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(&r, &s->volume, &r);
        pa_source_set_soft_volume(s, &r);

        pa_log_debug("Requested volume: %s", pa_cvolume_snprint(t, sizeof(t), &s->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), &r));

    } else

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

        s->volume = r;

    return 0;

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

    return -1;
}

static int 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 -1;
    }

    s->muted = !sw;

    return 0;
}

static int 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 -1;
    }

    return 0;
}

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;

/*         pa_log_debug("loop"); */

        /* Read some data and pass it to the sources */
        if (PA_SOURCE_IS_OPENED(u->source->thread_info.state)) {
            int work_done = 0;
            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 & (POLLOUT|POLLERR|POLLNVAL|POLLHUP|POLLPRI)) {
                if (pa_alsa_recover_from_poll(u->pcm_handle, revents) < 0)
                    goto fail;

                snd_pcm_start(u->pcm_handle);
            }

            if (revents && u->use_tsched)
                pa_log_debug("Wakeup from ALSA!%s%s", (revents & POLLIN) ? " INPUT" : "", (revents & POLLOUT) ? " OUTPUT" : "");
        } 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");
}

int pa__init(pa_module*m) {

    pa_modargs *ma = NULL;
    struct userdata *u = NULL;
    const char *dev_id;
    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;
    snd_pcm_info_t *pcm_info = NULL;
    int err;
    const char *name;
    char *name_buf = NULL;
    pa_bool_t namereg_fail;
    pa_bool_t use_mmap = TRUE, b, use_tsched = TRUE, d;
    pa_source_new_data data;

    snd_pcm_info_alloca(&pcm_info);

    pa_assert(m);

    pa_alsa_redirect_errors_inc();

    if (!(ma = pa_modargs_new(m->argument, valid_modargs))) {
        pa_log("Failed to parse module arguments");
        goto fail;
    }

    ss = m->core->default_sample_spec;
    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 (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;
    m->userdata = u;
    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, DEFAULT_TSCHED_WATERMARK_USEC, TRUE, 5);
    pa_smoother_set_time_offset(u->smoother, pa_rtclock_usec());

    snd_config_update_free_global();

    b = use_mmap;
    d = use_tsched;

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

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

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

    if ((err = snd_pcm_info(u->pcm_handle, pcm_info)) < 0) {
        pa_log("Error fetching PCM info: %s", snd_strerror(err));
        goto fail;
    }

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

    if ((err = snd_mixer_open(&u->mixer_handle, 0)) < 0)
        pa_log("Error opening mixer: %s", snd_strerror(err));
    else {
        pa_bool_t found = FALSE;

        if (pa_alsa_prepare_mixer(u->mixer_handle, u->device_name) >= 0)
            found = TRUE;
        else {
            snd_pcm_info_t* info;

            snd_pcm_info_alloca(&info);

            if (snd_pcm_info(u->pcm_handle, info) >= 0) {
                char *md;
                int card;

                if ((card = snd_pcm_info_get_card(info)) >= 0) {

                    md = pa_sprintf_malloc("hw:%i", card);

                    if (strcmp(u->device_name, md))
                        if (pa_alsa_prepare_mixer(u->mixer_handle, md) >= 0)
                            found = TRUE;
                    pa_xfree(md);
                }
            }
        }

        if (found)
            if (!(u->mixer_elem = pa_alsa_find_elem(u->mixer_handle, "Capture", "Mic", FALSE)))
                found = FALSE;

        if (!found) {
            snd_mixer_close(u->mixer_handle);
            u->mixer_handle = NULL;
        }
    }

    if ((name = pa_modargs_get_value(ma, "source_name", NULL)))
        namereg_fail = TRUE;
    else {
        name = name_buf = pa_sprintf_malloc("alsa_input.%s", u->device_name);
        namereg_fail = FALSE;
    }

    pa_source_new_data_init(&data);
    data.driver = __FILE__;
    data.module = m;
    pa_source_new_data_set_name(&data, name);
    data.namereg_fail = namereg_fail;
    pa_source_new_data_set_sample_spec(&data, &ss);
    pa_source_new_data_set_channel_map(&data, &map);

    pa_alsa_init_proplist(data.proplist, pcm_info);
    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"));

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

    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->hwbuf_unused_frames = 0;
    u->tsched_watermark = tsched_watermark;
    u->frame_index = 0;
    u->hw_dB_supported = FALSE;
    u->hw_dB_min = u->hw_dB_max = 0;
    u->hw_volume_min = u->hw_volume_max = 0;
    u->mixer_seperate_channels = FALSE;
    pa_cvolume_mute(&u->hardware_volume, u->source->sample_spec.channels);

    if (use_tsched)
        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 (u->mixer_handle) {
        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 (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.");
                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, &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");
            } 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, m->core->mainloop) < 0) {
            pa_log("Failed to initialize file descriptor monitoring");
            goto fail;
        }

        snd_mixer_elem_set_callback(u->mixer_elem, mixer_callback);
        snd_mixer_elem_set_callback_private(u->mixer_elem, u);
    } else
        u->mixer_fdl = NULL;

    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);

    pa_modargs_free(ma);

    return 0;

fail:

    if (ma)
        pa_modargs_free(ma);

    pa__done(m);

    return -1;
}

int pa__get_n_used(pa_module *m) {
    struct userdata *u;

    pa_assert(m);
    pa_assert_se(u = m->userdata);

    return pa_source_linked_by(u->source);
}

void pa__done(pa_module*m) {
    struct userdata *u;

    pa_assert(m);

    if (!(u = m->userdata)) {
        pa_alsa_redirect_errors_dec();
        return;
    }

    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);

    snd_config_update_free_global();
    pa_alsa_redirect_errors_dec();
}