On 03-04-08 20:54, akpm@linux-foundation.org wrote:

The patch titled es1968: fix jitter on some maestro cards has been added to the -mm tree. Its filename is es1968-fix-jitter-on-some-maestro-cards.patch

[ ... ]

Subject: es1968: fix jitter on some maestro cards From: Andreas Mueller <andreas@stapelspeicher.org>

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).

Cc: Rene Herman <rene.herman@keyaccess.nl> Cc: Jaroslav Kysela <perex@suse.cz> Cc: Takashi Iwai <tiwai@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> ---

Tested-By: Rene Herman <rene.herman@gmail.com> on a TerraTec DMX (ESS Canyon3D, ES1970MS-3D) which doesn't need this but doesn't seem to be suffering from it either. No idea about this otherwise.

sound/pci/es1968.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-)

diff -puN sound/pci/es1968.c~es1968-fix-jitter-on-some-maestro-cards sound/pci/es1968.c --- a/sound/pci/es1968.c~es1968-fix-jitter-on-some-maestro-cards +++ a/sound/pci/es1968.c @@ -1815,6 +1815,23 @@ snd_es1968_pcm(struct es1968 *chip, int

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 @@ -1936,8 +1953,11 @@ static irqreturn_t snd_es1968_interrupt( 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) {

Rene.