diff options
| author | Andreas Mueller <andreas@stapelspeicher.org> | 2008-04-14 13:08:05 +0200 |
|---|---|---|
| committer | Takashi Iwai <tiwai@suse.de> | 2008-04-24 12:00:33 +0200 |
| commit | f24bfa53dab478e1bde2d7fd39d3c1a69dc518f1 (patch) | |
| tree | 6c9285033393683f81dd82417677004e9693ebeb /sound/pci/es1968.c | |
| parent | 62cef8212ffa9df3e6c5b358ea2382d90489d590 (diff) | |
[ALSA] es1968: fix jitter on some maestro cards
This patch suppresses jitter on several Maestro cards in stereo mode (ALSA of
course).
The patch is also incorporated in the *BSD drivers where I "ported" it from.
Without this patch most of the stereo audio gets out of sync and really
distorted (oss-emulation with mplayer at 48000khz worked somehow).
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'sound/pci/es1968.c')
| -rw-r--r-- | sound/pci/es1968.c | 22 |
1 files changed, 21 insertions, 1 deletions
diff --git a/sound/pci/es1968.c b/sound/pci/es1968.c index 67f03264f871..f8f3bb662d17 100644 --- a/sound/pci/es1968.c +++ b/sound/pci/es1968.c @@ -1827,6 +1827,23 @@ snd_es1968_pcm(struct es1968 *chip, int device) return 0; } +/* + * suppress jitter on some maestros when playing stereo + */ +static void snd_es1968_suppress_jitter(struct es1968 *chip, struct esschan *es) +{ + unsigned int cp1; + unsigned int cp2; + unsigned int diff; + + cp1 = __apu_get_register(chip, 0, 5); + cp2 = __apu_get_register(chip, 1, 5); + diff = (cp1 > cp2 ? cp1 - cp2 : cp2 - cp1); + + if (diff > 1) { + __maestro_write(chip, IDR0_DATA_PORT, cp1); + } +} /* * update pointer @@ -1948,8 +1965,11 @@ static irqreturn_t snd_es1968_interrupt(int irq, void *dev_id) struct esschan *es; spin_lock(&chip->substream_lock); list_for_each_entry(es, &chip->substream_list, list) { - if (es->running) + if (es->running) { snd_es1968_update_pcm(chip, es); + if (es->fmt & ESS_FMT_STEREO) + snd_es1968_suppress_jitter(chip, es); + } } spin_unlock(&chip->substream_lock); if (chip->in_measurement) { |