ALSA: hda: Reduce CPU hog with SKL+ position reporting

index 47777439961c..9989ec4dc324 100644
@@ -637,13 +637,17 @@ static int azx_position_check(struct azx *chip, struct azx_dev *azx_dev)
  * the update-IRQ timing.  The IRQ is issued before actually the
  * data is processed.  So, we need to process it afterwords in a
  * workqueue.
+ *
+ * Returns 1 if OK to proceed, 0 for delay handling, -1 for skipping update
  */
 static int azx_position_ok(struct azx *chip, struct azx_dev *azx_dev)
 {
 	struct snd_pcm_substream *substream = azx_dev->core.substream;
+	struct snd_pcm_runtime *runtime = substream->runtime;
 	int stream = substream->stream;
 	u32 wallclk;
 	unsigned int pos;
+	snd_pcm_uframes_t hwptr, target;
 
 	wallclk = azx_readl(chip, WALLCLK) - azx_dev->core.start_wallclk;
 	if (wallclk < (azx_dev->core.period_wallclk * 2) / 3)

@@ -680,6 +684,24 @@ static int azx_position_ok(struct azx *chip, struct azx_dev *azx_dev)
 		/* NG - it's below the first next period boundary */
 		return chip->bdl_pos_adj ? 0 : -1;
 	azx_dev->core.start_wallclk += wallclk;
+
+	if (azx_dev->core.no_period_wakeup)
+		return 1; /* OK, no need to check period boundary */
+
+	if (runtime->hw_ptr_base != runtime->hw_ptr_interrupt)
+		return 1; /* OK, already in hwptr updating process */
+
+	/* check whether the period gets really elapsed */
+	pos = bytes_to_frames(runtime, pos);
+	hwptr = runtime->hw_ptr_base + pos;
+	if (hwptr < runtime->status->hw_ptr)
+		hwptr += runtime->buffer_size;
+	target = runtime->hw_ptr_interrupt + runtime->period_size;
+	if (hwptr < target) {
+		/* too early wakeup, process it later */
+		return chip->bdl_pos_adj ? 0 : -1;
+	}
+
 	return 1; /* OK, it's fine */
 }
 

@@ -874,11 +896,7 @@ static unsigned int azx_get_pos_skl(struct azx *chip, struct azx_dev *azx_dev)
 	if (azx_dev->core.substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
 		return azx_skl_get_dpib_pos(chip, azx_dev);
 
-	/* For capture, we need to read posbuf, but it requires a delay
-	 * for the possible boundary overlap; the read of DPIB fetches the
-	 * actual posbuf
-	 */
-	udelay(20);
+	/* read of DPIB fetches the actual posbuf */
 	azx_skl_get_dpib_pos(chip, azx_dev);
 	return azx_get_pos_posbuf(chip, azx_dev);
 }

index 9989ec4dc324..14298f015fba 100644
@@ -880,27 +880,6 @@ static int azx_get_delay_from_fifo(struct azx *chip, struct azx_dev *azx_dev,
 	return substream->runtime->delay;
 }
 
-static unsigned int azx_skl_get_dpib_pos(struct azx *chip,
-					 struct azx_dev *azx_dev)
-{
-	return _snd_hdac_chip_readl(azx_bus(chip),
-				    AZX_REG_VS_SDXDPIB_XBASE +
-				    (AZX_REG_VS_SDXDPIB_XINTERVAL *
-				     azx_dev->core.index));
-}
-
-/* get the current DMA position with correction on SKL+ chips */
-static unsigned int azx_get_pos_skl(struct azx *chip, struct azx_dev *azx_dev)
-{
-	/* DPIB register gives a more accurate position for playback */
-	if (azx_dev->core.substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
-		return azx_skl_get_dpib_pos(chip, azx_dev);
-
-	/* read of DPIB fetches the actual posbuf */
-	azx_skl_get_dpib_pos(chip, azx_dev);
-	return azx_get_pos_posbuf(chip, azx_dev);
-}
-
 static void __azx_shutdown_chip(struct azx *chip, bool skip_link_reset)
 {
 	azx_stop_chip(chip);

@@ -1590,7 +1569,7 @@ static void assign_position_fix(struct azx *chip, int fix)
 		[POS_FIX_POSBUF] = azx_get_pos_posbuf,
 		[POS_FIX_VIACOMBO] = azx_via_get_position,
 		[POS_FIX_COMBO] = azx_get_pos_lpib,
-		[POS_FIX_SKL] = azx_get_pos_skl,
+		[POS_FIX_SKL] = azx_get_pos_posbuf,
 		[POS_FIX_FIFO] = azx_get_pos_fifo,
 	};