diff options
| author | Clemens Ladisch <clemens@ladisch.de> | 2010-03-24 07:10:54 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-04-01 15:58:23 -0700 |
| commit | 7a1bd86e2609609c9e8d8a4589d75a383cbbbc61 (patch) | |
| tree | 3d0091c662ed4be500788d0d304971c87fe51efa /sound | |
| parent | f09315f7cd6cfdb98e90e6686116251bb026020b (diff) | |
ALSA: cmipci: work around invalid PCM pointer
commit 1c583063a5c769fe2ec604752e383972c69e6d9b upstream.
When the CMI8738 FRAME2 register is read, the chip sometimes (probably
when wrapping around) returns an invalid value that would be outside the
programmed DMA buffer. This leads to an inconsistent PCM pointer that is
likely to result in an underrun.
To work around this, read the register multiple times until we get a
valid value; the error state seems to be very short-lived.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Reported-and-tested-by: Matija Nalis <mnalis-alsadev@voyager.hr>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Diffstat (limited to 'sound')
| -rw-r--r-- | sound/pci/cmipci.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/sound/pci/cmipci.c b/sound/pci/cmipci.c index ddcd4a9fd7e..78c8736638d 100644 --- a/sound/pci/cmipci.c +++ b/sound/pci/cmipci.c @@ -941,13 +941,21 @@ static snd_pcm_uframes_t snd_cmipci_pcm_pointer(struct cmipci *cm, struct cmipci struct snd_pcm_substream *substream) { size_t ptr; - unsigned int reg; + unsigned int reg, rem, tries; + if (!rec->running) return 0; #if 1 // this seems better.. reg = rec->ch ? CM_REG_CH1_FRAME2 : CM_REG_CH0_FRAME2; - ptr = rec->dma_size - (snd_cmipci_read_w(cm, reg) + 1); - ptr >>= rec->shift; + for (tries = 0; tries < 3; tries++) { + rem = snd_cmipci_read_w(cm, reg); + if (rem < rec->dma_size) + goto ok; + } + printk(KERN_ERR "cmipci: invalid PCM pointer: %#x\n", rem); + return SNDRV_PCM_POS_XRUN; +ok: + ptr = (rec->dma_size - (rem + 1)) >> rec->shift; #else reg = rec->ch ? CM_REG_CH1_FRAME1 : CM_REG_CH0_FRAME1; ptr = snd_cmipci_read(cm, reg) - rec->offset; |