ALSA: au88x0 - Modify pointer callback to give accurate playback position

Signed-off-by: Raymond Yau <superquad.vortex2@gmail.com>
Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/au88x0/au88x0_core.c

@@ -1252,11 +1252,19 @@ static void vortex_adbdma_resetup(vortex_t *vortex, int adbdma) {
 static int inline vortex_adbdma_getlinearpos(vortex_t * vortex, int adbdma)
 {
 	stream_t *dma = &vortex->dma_adb[adbdma];
-	int temp;
+	int temp, page, delta;
 
 	temp = hwread(vortex->mmio, VORTEX_ADBDMA_STAT + (adbdma << 2));
-	temp = (dma->period_virt * dma->period_bytes) + (temp & (dma->period_bytes - 1));
-	return temp;
+	page = (temp & ADB_SUBBUF_MASK) >> ADB_SUBBUF_SHIFT;
+	if (dma->nr_periods >= 4)
+		delta = (page - dma->period_real) & 3;
+	else {
+		delta = (page - dma->period_real);
+		if (delta < 0)
+			delta += dma->nr_periods;
+	}
+	return (dma->period_virt + delta) * dma->period_bytes
+		+ (temp & (dma->period_bytes - 1));
 }
 
 static void vortex_adbdma_startfifo(vortex_t * vortex, int adbdma)