From c4ca3871e21fa085096316f5f8d9975cf3dfde1d Mon Sep 17 00:00:00 2001
From: Takashi Iwai <tiwai@suse.de>
Date: Wed, 29 Sep 2021 09:29:34 +0200
Subject: [PATCH] ALSA: hda: Use position buffer for SKL+ again
Git-commit: c4ca3871e21fa085096316f5f8d9975cf3dfde1d
Patch-mainline: v5.16-rc1
References: git-fixes stable-5.14.19

The commit f87e7f25893d ("ALSA: hda - Improved position reporting on
SKL+") changed the PCM position report for SKL+ chips to use DPIB, but
according to Pierre, DPIB is no best choice for the accurate position
reports and it often reports too early.  The recommended method is
rather the classical position buffer.

This patch makes the PCM position reporting on SKL+ back to the
position buffer again.

Fixes: f87e7f25893d ("ALSA: hda - Improved position reporting on SKL+")
Suggested-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210929072934.6809-3-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>

---
 sound/pci/hda/hda_intel.c |   23 +----------------------
 1 file changed, 1 insertion(+), 22 deletions(-)

--- a/sound/pci/hda/hda_intel.c
+++ b/sound/pci/hda/hda_intel.c
@@ -881,27 +881,6 @@ static int azx_get_delay_from_fifo(struc
 	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);
@@ -1591,7 +1570,7 @@ static void assign_position_fix(struct a
 		[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,
 	};