openwrt/target/linux/s3c24xx/patches-2.6.26/0184-workaround-s3c24xx-i2s-stop-live-stream-stall-on-res.patch

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From f4dac01cd9cb5b7a33fb336fbf9065dbd7e38efe Mon Sep 17 00:00:00 2001
From: Andy Green <andy@openmoko.com>
Date: Fri, 25 Jul 2008 23:06:15 +0100
Subject: [PATCH] workaround-s3c24xx-i2s-stop-live-stream-stall-on-resume.patch
Reported-by: Graeme Gregory <graeme@openmoko.org>
Basically-solved-by: Graeme Gregory <graeme@openmoko.org>
Graeme found a while back that on resume, IISCON register in
s3c2442 does not show LRCK toggling in LRINDEX bit any more,
causing s3c24xx_snd_lrsync() to timeout and return an error,
aborting restart of any live stream that was playing at
suspend.
I confirmed it was true, meddled around for a bit looking
for some magic to restart LRCK or at least the reporting of
it, and in the end worked around it using the method noted
by Graeme: just ignore LRCK sync if it timed out. The worst
that could happen would be L and R swap for the duration of
stream that was suspended into but probably not even that.
Signed-off-by: Andy Green <andy@openmoko.com>
---
sound/soc/s3c24xx/s3c24xx-i2s.c | 15 +++++++++------
1 files changed, 9 insertions(+), 6 deletions(-)
diff --git a/sound/soc/s3c24xx/s3c24xx-i2s.c b/sound/soc/s3c24xx/s3c24xx-i2s.c
index 1ed6afd..fce667c 100644
--- a/sound/soc/s3c24xx/s3c24xx-i2s.c
+++ b/sound/soc/s3c24xx/s3c24xx-i2s.c
@@ -180,7 +180,7 @@ static void s3c24xx_snd_rxctrl(int on)
static int s3c24xx_snd_lrsync(void)
{
u32 iiscon;
- unsigned long timeout = jiffies + msecs_to_jiffies(5);
+ int timeout = 5; /* 500us, 125 should be enough at 8kHz */
DBG("Entered %s\n", __func__);
@@ -286,11 +286,14 @@ static int s3c24xx_i2s_trigger(struct snd_pcm_substream *substream, int cmd)
case SNDRV_PCM_TRIGGER_START:
case SNDRV_PCM_TRIGGER_RESUME:
case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
- if (!s3c24xx_snd_is_clkmaster()) {
- ret = s3c24xx_snd_lrsync();
- if (ret)
- goto exit_err;
- }
+ if (!s3c24xx_snd_is_clkmaster())
+ /* we ignore the return code, if it sync'd then fine,
+ * if it didn't sync, which happens after resume the
+ * first time when there was a live stream at suspend,
+ * just let it timeout, the stream picks up OK after
+ * that and LRCK is evidently working again.
+ */
+ s3c24xx_snd_lrsync();
if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
s3c24xx_snd_rxctrl(1);
--
1.5.6.3