[ALSA] [ML403-AC97CR] Fix capture/periodic overrun bug

We have to do fairly accurate counting of the minimal periods, instead
of being lazy and just setting the number to zero as soon as one period
elapses.
Signed-off-by: Joachim Foerster <JOFT@gmx.de>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>

sound/drivers/ml403-ac97cr.c

@@ -28,11 +28,9 @@
  * accesses to a minimum, because after a variable amount of accesses, the AC97
  * controller doesn't raise the register access finished bit anymore ...
  *
- * - Capture support works - basically, but after ~30s (with rates > ~20kHz)
- * ALSA stops reading captured samples from the intermediate buffer and
- * therefore a overrun happens - ATM I don't know what's wrong.
- *
  * - Playback support seems to be pretty stable - no issues here.
+ * - Capture support "works" now, too. Overruns don't happen any longer so often.
+ *   But there might still be some ...
  */
 
 #include <sound/driver.h>

sound/drivers/pcm-indirect2.c

@@ -403,7 +403,7 @@ snd_pcm_indirect2_playback_interrupt(struct snd_pcm_substream *substream,
 					  rec->min_multiple);
 		rec->mul_elapsed++;
 #endif
-		rec->min_periods = 0;
+		rec->min_periods = (rec->min_periods % rec->min_multiple);
 		snd_pcm_period_elapsed(substream);
 	}
 }
@@ -568,24 +568,8 @@ snd_pcm_indirect2_capture_interrupt(struct snd_pcm_substream *substream,
 		rec->mul_elapsed_real += (rec->min_periods /
 					  rec->min_multiple);
 		rec->mul_elapsed++;
-
-		if (!(rec->mul_elapsed % 4)) {
-			struct snd_pcm_runtime *runtime = substream->runtime;
-			unsigned int appl_ptr =
-			    frames_to_bytes(runtime,
-					    (unsigned int)runtime->control->
-					    appl_ptr) % rec->sw_buffer_size;
-			int diff = rec->sw_data - appl_ptr;
-			if (diff < 0)
-				diff += rec->sw_buffer_size;
-			snd_printk(KERN_DEBUG
-				   "STAT: mul_elapsed: %d, sw_data: %u, "
-				   "appl_ptr (bytes): %u, diff: %d\n",
-				   rec->mul_elapsed, rec->sw_data, appl_ptr,
-				   diff);
-		}
 #endif
-		rec->min_periods = 0;
+		rec->min_periods = (rec->min_periods % rec->min_multiple);
 		snd_pcm_period_elapsed(substream);
 	}
 }