define minimal and maximal wakeup/sleep times; check for underrun condition only...

[pulseaudio] / src / modules / module-alsa-sink.c

/* $Id$ */

/***
  This file is part of PulseAudio.

  Copyright 2004-2006 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>

#include <pulse/xmalloc.h>
#include <pulse/util.h>
#include <pulse/timeval.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/rtclock.h>
#include <pulsecore/time-smoother.h>

#include "alsa-util.h"
#include "module-alsa-sink-symdef.h"

PA_MODULE_AUTHOR("Lennart Poettering");
PA_MODULE_DESCRIPTION("ALSA Sink");
PA_MODULE_VERSION(PACKAGE_VERSION);
PA_MODULE_LOAD_ONCE(FALSE);
PA_MODULE_USAGE(
        "sink_name=<name for the sink> "
        "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=<lower fill watermark> "
        "mixer_reset=<reset hw volume and mute settings to sane defaults when falling back to software?>");

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

#define DEFAULT_DEVICE "default"
#define DEFAULT_TSCHED_BUFFER_USEC (5*PA_USEC_PER_SEC)           /* 5s */
#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_sink *sink;

    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;

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

    char *device_name;

    pa_bool_t use_mmap, use_tsched;

    pa_bool_t first, after_rewind;

    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 - u->hwbuf_unused_frames * u->frame_size;

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

    if (min_sleep > max_use/2)
        min_sleep = pa_frame_align(max_use/2, &u->sink->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->sink->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 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));

    if (err == -EAGAIN) {
        pa_log_debug("%s: EAGAIN", call);
        return 1;
    }

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

    if ((err = snd_pcm_recover(u->pcm_handle, err, 1)) == 0) {
        u->first = TRUE;
        return 0;
    }

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

static void check_left_to_play(struct userdata *u, snd_pcm_sframes_t n) {
    size_t left_to_play;

    if (u->first || u->after_rewind)
        return;

    if (n*u->frame_size < u->hwbuf_size)
        left_to_play = u->hwbuf_size - (n*u->frame_size);
    else
        left_to_play = 0;

    if (left_to_play > 0)
        pa_log_debug("%0.2f ms left to play", (double) pa_bytes_to_usec(left_to_play, &u->sink->sample_spec) / PA_USEC_PER_MSEC);
    else {
        pa_log_info("Underrun!");

        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->sink->sample_spec) / PA_USEC_PER_MSEC);
        }
    }
}

static int mmap_write(struct userdata *u) {
    int work_done = 0;
    pa_bool_t checked_left_to_play = FALSE;

    pa_assert(u);
    pa_sink_assert_ref(u->sink);

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

        snd_pcm_hwsync(u->pcm_handle);

        /* First we determine how many samples are missing to fill the
         * buffer up to 100% */

        if (PA_UNLIKELY((n = snd_pcm_avail_update(u->pcm_handle)) < 0)) {

            if ((r = try_recover(u, "snd_pcm_avail_update", n)) == 0)
                continue;
            else if (r > 0)
                return work_done;

            return r;
        }

        if (!checked_left_to_play) {
            check_left_to_play(u, n);
            checked_left_to_play = TRUE;
        }

        /* We only use part of the buffer that matches our
         * dynamically requested latency */

        if (PA_UNLIKELY(n <= u->hwbuf_unused_frames))
            return work_done;

        frames = n = n - u->hwbuf_unused_frames;

        pa_log_debug("%lu frames to write", (unsigned long) frames);

        if (PA_UNLIKELY((err = snd_pcm_mmap_begin(u->pcm_handle, &areas, &offset, &frames)) < 0)) {

            if ((r = try_recover(u, "snd_pcm_mmap_begin", err)) == 0)
                continue;
            else if (r > 0)
                return work_done;

            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->sink->core->mempool)/u->frame_size)
            frames = pa_mempool_block_size_max(u->sink->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_sink_render_into_full(u->sink, &chunk);

        /* FIXME: Maybe we can do something to keep this memory block
         * a little bit longer around? */
        pa_memblock_unref_fixed(chunk.memblock);

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

            if ((r = try_recover(u, "snd_pcm_mmap_commit", err)) == 0)
                continue;
            else if (r > 0)
                return work_done;

            return r;
        }

        work_done = 1;

        u->frame_index += frames;

        pa_log_debug("wrote %lu frames", (unsigned long) frames);

        if (PA_LIKELY(frames >= (snd_pcm_uframes_t) n))
            return work_done;
    }
}

static int unix_write(struct userdata *u) {
    int work_done = 0;
    pa_bool_t checked_left_to_play = FALSE;

    pa_assert(u);
    pa_sink_assert_ref(u->sink);

    for (;;) {
        void *p;
        snd_pcm_sframes_t n, frames;
        int r;

        snd_pcm_hwsync(u->pcm_handle);

        if (PA_UNLIKELY((n = snd_pcm_avail_update(u->pcm_handle)) < 0)) {

            if ((r = try_recover(u, "snd_pcm_avail_update", n)) == 0)
                continue;
            else if (r > 0)
                return work_done;

            return r;
        }

        if (!checked_left_to_play) {
            check_left_to_play(u, n);
            checked_left_to_play = TRUE;
        }

        if (PA_UNLIKELY(n <= u->hwbuf_unused_frames))
            return work_done;

        n -= u->hwbuf_unused_frames;

        pa_log_debug("%lu frames to write", (unsigned long) frames);

        if (u->memchunk.length <= 0)
            pa_sink_render(u->sink, n * u->frame_size, &u->memchunk);

        pa_assert(u->memchunk.length > 0);

        frames = u->memchunk.length / u->frame_size;

        if (frames > n)
            frames = n;

        p = pa_memblock_acquire(u->memchunk.memblock);
        frames = snd_pcm_writei(u->pcm_handle, (const uint8_t*) p + u->memchunk.index, frames);
        pa_memblock_release(u->memchunk.memblock);

        pa_assert(frames != 0);

        if (PA_UNLIKELY(frames < 0)) {

            if ((r = try_recover(u, "snd_pcm_writei", n)) == 0)
                continue;
            else if (r > 0)
                return work_done;

            return r;
        }

        u->memchunk.index += frames * u->frame_size;
        u->memchunk.length -= frames * u->frame_size;

        if (u->memchunk.length <= 0) {
            pa_memblock_unref(u->memchunk.memblock);
            pa_memchunk_reset(&u->memchunk);
        }

        work_done = 1;

        u->frame_index += frames;

        pa_log_debug("wrote %lu frames", (unsigned long) frames);

        if (PA_LIKELY(frames >= n))
            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;
/*     struct timeval timestamp; */
    snd_pcm_status_t *status;

    snd_pcm_status_alloca(&status);

    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_status(u->pcm_handle, status)) < 0)) { */
/*         pa_log("Failed to query DSP status data: %s", snd_strerror(err)); */
/*         return; */
/*     } */

/*     delay = snd_pcm_status_get_delay(status); */

    if (PA_UNLIKELY((err = snd_pcm_delay(u->pcm_handle, &delay)) < 0)) {
        pa_log("Failed to query DSP status data: %s", snd_strerror(err));
        return;
    }

    frames = u->frame_index - delay;

/*     pa_log_debug("frame_index = %llu, delay = %llu, p = %llu", (unsigned long long) u->frame_index, (unsigned long long) delay, (unsigned long long) frames); */

/*     snd_pcm_status_get_tstamp(status, &timestamp); */
/*     pa_rtclock_from_wallclock(&timestamp); */
/*     now1 = pa_timeval_load(&timestamp); */

    now1 = pa_rtclock_usec();
    now2 = pa_bytes_to_usec(frames * u->frame_size, &u->sink->sample_spec);
    pa_smoother_put(u->smoother, now1, now2);
}

static pa_usec_t sink_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) pa_bytes_to_usec(u->frame_index * u->frame_size, &u->sink->sample_spec) - (int64_t) now2;

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

    if (u->memchunk.memblock)
        r += pa_bytes_to_usec(u->memchunk.length, &u->sink->sample_spec);

    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_drain(u->pcm_handle);
    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 pa_usec_t hw_sleep_time(struct userdata *u) {
    pa_usec_t usec, wm;

    pa_assert(u);

    usec = pa_sink_get_requested_latency_within_thread(u->sink);

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

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

    if (u->first) {
        pa_log_debug("Decreasing wakeup time for the first iteration by half.");
        usec /= 2;
    }

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

    return usec;
}

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_sink_get_requested_latency_within_thread(u->sink)) != (pa_usec_t) -1) {
            size_t b;

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

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

    /* We need at last one frame in the used part of the buffer */
    avail_min = u->hwbuf_unused_frames + 1;

    if (u->use_tsched) {
        pa_usec_t usec;

        usec = hw_sleep_time(u);
        avail_min += pa_usec_to_bytes(usec, &u->sink->sample_spec);
    }

    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_PLAYBACK, SND_PCM_NONBLOCK)) < 0) {
        pa_log("Error opening PCM device %s: %s", u->device_name, snd_strerror(err));
        goto fail;
    }

    ss = u->sink->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->sink->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.");
        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 */

    u->first = TRUE;

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

    switch (code) {

        case PA_SINK_MESSAGE_GET_LATENCY: {
            pa_usec_t r = 0;

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

            *((pa_usec_t*) data) = r;

            return 0;
        }

        case PA_SINK_MESSAGE_SET_STATE:

            switch ((pa_sink_state_t) PA_PTR_TO_UINT(data)) {

                case PA_SINK_SUSPENDED:
                    pa_assert(PA_SINK_OPENED(u->sink->thread_info.state));

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

                    break;

                case PA_SINK_IDLE:
                case PA_SINK_RUNNING:

                    if (u->sink->thread_info.state == PA_SINK_INIT) {
                        if (build_pollfd(u) < 0)
                            return -1;
                    }

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

                    break;

                case PA_SINK_UNLINKED:
                case PA_SINK_INIT:
                    ;
            }

            break;
    }

    return pa_sink_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_sink_get_volume(u->sink);
        pa_sink_get_mute(u->sink);
    }

    return 0;
}

static int sink_get_volume_cb(pa_sink *s) {
    struct userdata *u = s->userdata;
    int err;
    int i;

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

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

        pa_assert(snd_mixer_selem_has_playback_channel(u->mixer_elem, u->mixer_map[i]));

        if (u->hw_dB_supported) {

            if ((err = snd_mixer_selem_get_playback_dB(u->mixer_elem, u->mixer_map[i], &alsa_vol)) >= 0) {
                s->volume.values[i] = pa_sw_volume_from_dB(alsa_vol / 100.0);
                continue;
            }

            u->hw_dB_supported = FALSE;
        }

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

        s->volume.values[i] = (pa_volume_t) roundf(((float) (alsa_vol - u->hw_volume_min) * PA_VOLUME_NORM) / (u->hw_volume_max - u->hw_volume_min));
    }

    return 0;

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

    return -1;
}

static int sink_set_volume_cb(pa_sink *s) {
    struct userdata *u = s->userdata;
    int err;
    int i;

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

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

        pa_assert(snd_mixer_selem_has_playback_channel(u->mixer_elem, u->mixer_map[i]));

        vol = PA_MIN(s->volume.values[i], PA_VOLUME_NORM);

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

            if ((err = snd_mixer_selem_set_playback_dB(u->mixer_elem, u->mixer_map[i], alsa_vol, -1)) >= 0) {

                if (snd_mixer_selem_get_playback_dB(u->mixer_elem, u->mixer_map[i], &alsa_vol) >= 0)
                    s->volume.values[i] = pa_sw_volume_from_dB(alsa_vol / 100.0);

                continue;
            }

            u->hw_dB_supported = FALSE;

        }

        alsa_vol = (long) roundf(((float) vol * (u->hw_volume_max - u->hw_volume_min)) / PA_VOLUME_NORM) + u->hw_volume_min;
        alsa_vol = PA_CLAMP_UNLIKELY(alsa_vol, u->hw_volume_min, u->hw_volume_max);

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

        if (snd_mixer_selem_get_playback_volume(u->mixer_elem, u->mixer_map[i], &alsa_vol) >= 0)
            s->volume.values[i] = (pa_volume_t) roundf(((float) (alsa_vol - u->hw_volume_min) * PA_VOLUME_NORM) / (u->hw_volume_max - u->hw_volume_min));
    }

    return 0;

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

    return -1;
}

static int sink_get_mute_cb(pa_sink *s) {
    struct userdata *u = s->userdata;
    int err, sw;

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

    if ((err = snd_mixer_selem_get_playback_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 sink_set_mute_cb(pa_sink *s) {
    struct userdata *u = s->userdata;
    int err;

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

    if ((err = snd_mixer_selem_set_playback_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 sink_update_requested_latency_cb(pa_sink *s) {
    struct userdata *u = s->userdata;
    pa_assert(u);

    update_sw_params(u);
}

static int process_rewind(struct userdata *u) {
    snd_pcm_sframes_t unused;
    size_t rewind_nbytes, unused_nbytes, limit_nbytes;
    pa_assert(u);

    rewind_nbytes = u->sink->thread_info.rewind_nbytes;
    u->sink->thread_info.rewind_nbytes = 0;

    pa_assert(rewind_nbytes > 0);
    pa_log_debug("Requested to rewind %lu bytes.", (unsigned long) rewind_nbytes);

    snd_pcm_hwsync(u->pcm_handle);
    if ((unused = snd_pcm_avail_update(u->pcm_handle)) < 0) {
        pa_log("snd_pcm_avail_update() failed: %s", snd_strerror(unused));
        return -1;
    }

    unused_nbytes = u->tsched_watermark + (size_t) unused * u->frame_size;

    if (u->hwbuf_size > unused_nbytes)
        limit_nbytes = u->hwbuf_size - unused_nbytes;
    else
        limit_nbytes = 0;

    if (rewind_nbytes > limit_nbytes)
        rewind_nbytes = limit_nbytes;

    if (rewind_nbytes > 0) {
        snd_pcm_sframes_t in_frames, out_frames;

        pa_log_debug("Limited to %lu bytes.", (unsigned long) rewind_nbytes);

        in_frames = (snd_pcm_sframes_t) rewind_nbytes / u->frame_size;
        pa_log_debug("before: %lu", (unsigned long) in_frames);
        if ((out_frames = snd_pcm_rewind(u->pcm_handle, in_frames)) < 0) {
            pa_log("snd_pcm_rewind() failed: %s", snd_strerror(out_frames));
            return -1;
        }
        pa_log_debug("after: %lu", (unsigned long) out_frames);

        rewind_nbytes = out_frames * u->frame_size;

        if (rewind_nbytes <= 0)
            pa_log_info("Tried rewind, but was apparently not possible.");
        else {
            u->frame_index -= out_frames;
            pa_log_debug("Rewound %lu bytes.", (unsigned long) rewind_nbytes);
            pa_sink_process_rewind(u->sink, rewind_nbytes);

            u->after_rewind = TRUE;
        }
    } else
        pa_log_debug("Mhmm, actually there is nothing to rewind.");

    return 0;
}

static void thread_func(void *userdata) {
    struct userdata *u = userdata;

    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"); */

        /* Render some data and write it to the dsp */
        if (PA_SINK_OPENED(u->sink->thread_info.state)) {
            int work_done = 0;

            if (u->sink->thread_info.rewind_nbytes > 0)
                if (process_rewind(u) < 0)
                    goto fail;

            if (u->use_mmap)
                work_done = mmap_write(u);
            else
                work_done = unix_write(u);

            if (work_done < 0)
                goto fail;

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

            if (work_done) {

                if (u->first) {
                    pa_log_info("Starting playback.");
                    snd_pcm_start(u->pcm_handle);

                    pa_smoother_resume(u->smoother, pa_rtclock_usec());
                }

                update_smoother(u);
            }

            if (u->use_tsched) {
                pa_usec_t usec, cusec;

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

                usec = hw_sleep_time(u);

/*                 pa_log_debug("Waking up in %0.2fms (sound card clock).", (double) 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(), 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(usec, cusec));
            }

            u->first = FALSE;
            u->after_rewind = FALSE;

        } 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, 1)) < 0)
            goto fail;

        if (ret == 0)
            goto finish;

        /* Tell ALSA about this and process its response */
        if (PA_SINK_OPENED(u->sink->thread_info.state)) {
            struct pollfd *pollfd;
            unsigned short revents = 0;
            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 & (POLLERR|POLLNVAL|POLLHUP)) {
                if (pa_alsa_recover_from_poll(u->pcm_handle, revents) < 0)
                    goto fail;

                u->first = TRUE;
            }

            if (revents)
                pa_log_debug("Wakeup from ALSA! (%i)", revents);
        }
    }

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, mixer_reset = TRUE;
    pa_usec_t usec;
    pa_sink_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 and channel map");
        goto fail;
    }

    frame_size = pa_frame_size(&ss);

    nfrags = m->core->default_n_fragments;
    frag_size = pa_usec_to_bytes(m->core->default_fragment_size_msec*PA_USEC_PER_MSEC, &ss);
    if (frag_size <= 0)
        frag_size = frame_size;
    tsched_size = pa_usec_to_bytes(DEFAULT_TSCHED_BUFFER_USEC, &ss);
    tsched_watermark = 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("Disabling timer-based scheduling because high-resolution timers are not available from the kernel.");
        use_tsched = FALSE;
    }

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

    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->first = TRUE;
    u->after_rewind = FALSE;
    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_BUFFER_USEC*2, DEFAULT_TSCHED_BUFFER_USEC*2, TRUE);
    usec = pa_rtclock_usec();
    pa_smoother_set_time_offset(u->smoother, usec);
    pa_smoother_pause(u->smoother, 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_PLAYBACK,
                      &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_PLAYBACK,
                      &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_warn("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, "Master", "PCM")))
                found = FALSE;

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

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

    pa_sink_new_data_init(&data);
    data.driver = __FILE__;
    data.module = m;
    pa_sink_new_data_set_name(&data, name);
    data.namereg_fail = namereg_fail;
    pa_sink_new_data_set_sample_spec(&data, &ss);
    pa_sink_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->sink = pa_sink_new(m->core, &data, PA_SINK_HARDWARE|PA_SINK_LATENCY);
    pa_sink_new_data_done(&data);
    pa_xfree(name_buf);

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

    u->sink->parent.process_msg = sink_process_msg;
    u->sink->update_requested_latency = sink_update_requested_latency_cb;
    u->sink->userdata = u;

    pa_sink_set_asyncmsgq(u->sink, u->thread_mq.inq);
    pa_sink_set_rtpoll(u->sink, u->rtpoll);

    u->frame_size = frame_size;
    u->fragment_size = frag_size = 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;

    if (use_tsched)
        fix_tsched_watermark(u);

    u->sink->thread_info.max_rewind = use_tsched ? u->hwbuf_size : 0;
    u->sink->max_latency = pa_bytes_to_usec(u->hwbuf_size, &ss);
    if (!use_tsched)
        u->sink->min_latency = u->sink->max_latency;

    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;

    pa_memchunk_reset(&u->memchunk);

    if (u->mixer_handle) {
        pa_assert(u->mixer_elem);

        if (snd_mixer_selem_has_playback_volume(u->mixer_elem))

            if (pa_alsa_calc_mixer_map(u->mixer_elem, &map, u->mixer_map, TRUE) >= 0 &&
                snd_mixer_selem_get_playback_volume_range(u->mixer_elem, &u->hw_volume_min, &u->hw_volume_max) >= 0) {

                pa_bool_t suitable = TRUE;

                pa_log_info("Volume ranges from %li to %li.", u->hw_volume_min, u->hw_volume_max);

                if (u->hw_volume_min > u->hw_volume_max) {

                    pa_log_info("Minimal volume %li larger than maximum volume %li. Strange stuff Falling back to software volume control.", u->hw_volume_min, u->hw_volume_max);
                    suitable = FALSE;

                } else if (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;

                } else if (snd_mixer_selem_get_playback_dB_range(u->mixer_elem, &u->hw_dB_min, &u->hw_dB_max) >= 0) {

                    pa_log_info("Volume ranges from %0.2f dB to %0.2f dB.", u->hw_dB_min/100.0, u->hw_dB_max/100.0);

                    /* Let's see if this thing actually is useful for muting */
                    if (u->hw_dB_min > -6000) {
                        pa_log_info("Device cannot attenuate for more than -60 dB (only %0.2f dB supported), falling back to software volume control.", ((double) u->hw_dB_min) / 100);

                        suitable = FALSE;
                    } else if (u->hw_dB_max < 0) {

                        pa_log_info("Device is still attenuated at maximum volume setting (%0.2f dB is maximum). Strange stuff. Falling back to software volume control.", ((double) u->hw_dB_max) / 100);
                        suitable = FALSE;

                    } else if (u->hw_dB_min >= u->hw_dB_max) {

                        pa_log_info("Minimal dB (%0.2f) larger or equal to maximum dB (%0.2f). Strange stuff. Falling back to software volume control.", ((double) u->hw_dB_min) / 100, ((double) u->hw_dB_max) / 100);
                        suitable = FALSE;

                    } else {

                        if (u->hw_dB_max > 0) {
                            /* dB > 0 means overamplification, and clipping, we don't want that here */
                            pa_log_info("Device can do overamplification for %0.2f dB. Limiting to 0 db", ((double) u->hw_dB_max) / 100);
                            u->hw_dB_max = 0;
                        }

                        u->hw_dB_supported = TRUE;
                    }
                }

                if (suitable) {
                    u->sink->get_volume = sink_get_volume_cb;
                    u->sink->set_volume = sink_set_volume_cb;
                    u->sink->flags |= PA_SINK_HW_VOLUME_CTRL | (u->hw_dB_supported ? PA_SINK_DECIBEL_VOLUME : 0);
                    pa_log_info("Using hardware volume control. Hardware dB scale %s.", u->hw_dB_supported ? "supported" : "not supported");

                } else if (mixer_reset) {
                    pa_log_info("Using software volume control. Trying to reset sound card to 0 dB.");
                    pa_alsa_0dB_playback(u->mixer_elem);
                } else
                    pa_log_info("Using software volume control. Leaving hw mixer controls untouched.");
            }

        if (snd_mixer_selem_has_playback_switch(u->mixer_elem)) {
            u->sink->get_mute = sink_get_mute_cb;
            u->sink->set_mute = sink_set_mute_cb;
            u->sink->flags |= PA_SINK_HW_MUTE_CTRL;
        }

        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->sink->set_volume)
            u->sink->set_volume(u->sink);
    } else {
        if (u->sink->get_volume)
            u->sink->get_volume(u->sink);
    }

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

    pa_sink_put(u->sink);

    pa_modargs_free(ma);

    return 0;

fail:

    if (ma)
        pa_modargs_free(ma);

    pa__done(m);

    return -1;
}

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

    pa_assert(m);

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

    if (u->sink)
        pa_sink_unlink(u->sink);

    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->sink)
        pa_sink_unref(u->sink);

    if (u->memchunk.memblock)
        pa_memblock_unref(u->memchunk.memblock);

    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();
}