ALSA: pcxhr: Fix a counter wrap

fix a counter wrap to avoid resynchronization of stream positions every several
minutes. The resynchronization may create stream position jitter
Signed-off-by: Markus Bollinger <bollinger@digigram.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/pcxhr/pcxhr_core.c

@@ -1133,13 +1133,12 @@ static u_int64_t pcxhr_stream_read_position(struct pcxhr_mgr *mgr,
 	hw_sample_count = ((u_int64_t)rmh.stat[0]) << 24;
 	hw_sample_count += (u_int64_t)rmh.stat[1];
 
-	snd_printdd("stream %c%d : abs samples real(%ld) timer(%ld)\n",
+	snd_printdd("stream %c%d : abs samples real(%llu) timer(%llu)\n",
 		    stream->pipe->is_capture ? 'C' : 'P',
 		    stream->substream->number,
-		    (long unsigned int)hw_sample_count,
-		    (long unsigned int)(stream->timer_abs_periods +
-					stream->timer_period_frag +
-					mgr->granularity));
+		    hw_sample_count,
+		    stream->timer_abs_periods + stream->timer_period_frag +
+						mgr->granularity);
 	return hw_sample_count;
 }
 
@@ -1243,10 +1242,18 @@ irqreturn_t pcxhr_interrupt(int irq, void *dev_id)
 
 		if ((dsp_time_diff < 0) &&
 		    (mgr->dsp_time_last != PCXHR_DSP_TIME_INVALID)) {
-			snd_printdd("ERROR DSP TIME old(%d) new(%d) -> "
-				    "resynchronize all streams\n",
+			/* handle dsp counter wraparound without resync */
+			int tmp_diff = dsp_time_diff + PCXHR_DSP_TIME_MASK + 1;
+			snd_printdd("WARNING DSP timestamp old(%d) new(%d)",
 				    mgr->dsp_time_last, dsp_time_new);
-			mgr->dsp_time_err++;
+			if (tmp_diff > 0 && tmp_diff <= (2*mgr->granularity)) {
+				snd_printdd("-> timestamp wraparound OK: "
+					    "diff=%d\n", tmp_diff);
+				dsp_time_diff = tmp_diff;
+			} else {
+				snd_printdd("-> resynchronize all streams\n");
+				mgr->dsp_time_err++;
+			}
 		}
 #ifdef CONFIG_SND_DEBUG_VERBOSE
 		if (dsp_time_diff == 0)