ALSA: ca0106 - clean up playback pointer callback
Clean up the playback pointer callback function a bit, and make the
pointer check more strictly to avoid bogus pointers.
Signed-off-by: Takashi Iwai <tiwai@suse.de>
diff --git a/sound/pci/ca0106/ca0106_main.c b/sound/pci/ca0106/ca0106_main.c
index 0a3d3d6..8e69620 100644
--- a/sound/pci/ca0106/ca0106_main.c
+++ b/sound/pci/ca0106/ca0106_main.c
@@ -1002,29 +1002,27 @@
struct snd_ca0106 *emu = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
struct snd_ca0106_pcm *epcm = runtime->private_data;
- snd_pcm_uframes_t ptr, ptr1, ptr2,ptr3,ptr4 = 0;
+ unsigned int ptr, prev_ptr;
int channel = epcm->channel_id;
+ int timeout = 10;
if (!epcm->running)
return 0;
- ptr3 = snd_ca0106_ptr_read(emu, PLAYBACK_LIST_PTR, channel);
- ptr1 = snd_ca0106_ptr_read(emu, PLAYBACK_POINTER, channel);
- ptr4 = snd_ca0106_ptr_read(emu, PLAYBACK_LIST_PTR, channel);
- if (ptr3 != ptr4) ptr1 = snd_ca0106_ptr_read(emu, PLAYBACK_POINTER, channel);
- ptr2 = bytes_to_frames(runtime, ptr1);
- ptr2+= (ptr4 >> 3) * runtime->period_size;
- ptr=ptr2;
- if (ptr >= runtime->buffer_size)
- ptr -= runtime->buffer_size;
- /*
- printk(KERN_DEBUG "ptr1 = 0x%lx, ptr2=0x%lx, ptr=0x%lx, "
- "buffer_size = 0x%x, period_size = 0x%x, bits=%d, rate=%d\n",
- ptr1, ptr2, ptr, (int)runtime->buffer_size,
- (int)runtime->period_size, (int)runtime->frame_bits,
- (int)runtime->rate);
- */
- return ptr;
+ prev_ptr = -1;
+ do {
+ ptr = snd_ca0106_ptr_read(emu, PLAYBACK_LIST_PTR, channel);
+ ptr = (ptr >> 3) * runtime->period_size;
+ ptr += bytes_to_frames(runtime,
+ snd_ca0106_ptr_read(emu, PLAYBACK_POINTER, channel));
+ if (ptr >= runtime->buffer_size)
+ ptr -= runtime->buffer_size;
+ if (prev_ptr == ptr)
+ return ptr;
+ prev_ptr = ptr;
+ } while (--timeout);
+ snd_printk(KERN_WARNING "ca0106: unstable DMA pointer!\n");
+ return 0;
}
/* pointer_capture callback */