ALSA: hda/tas2781: do not use regcache

There are two problems with using regcache in this module.

The amplifier has 3 addressing levels (BOOK, PAGE, REG). The firmware
contains blocks that must be written to BOOK 0x8C. The regcache doesn't
know anything about BOOK, so regcache_sync writes invalid values to the
actual BOOK.

The module handles 2 or more separate amplifiers. The amplifiers have
different register values, and the module uses only one regmap/regcache
for all the amplifiers. The regcache_sync only writes the last amplifier
used.

The module successfully restores all the written register values (RC
profile, program, configuration, calibration) without regcache.

Remove regcache functions and set regmap cache_type to REGCACHE_NONE.

Link: https://lore.kernel.org/r/21a183b5a08cb23b193af78d4b1114cc59419272.1701906455.git.soyer@irl.hu/

Fixes: 5be27f1e ("ALSA: hda/tas2781: Add tas2781 HDA driver")
Acked-by: Mark Brown <broonie@kernel.org>
CC: stable@vger.kernel.org
Signed-off-by: Gergo Koteles <soyer@irl.hu>
Link: https://lore.kernel.org/r/491aeed0e2eecc3b704ec856f815db21bad3ba0e.1703202126.git.soyer@irl.huSigned-off-by: Takashi Iwai <tiwai@suse.de>

sound/pci/hda/tas2781_hda_i2c.c

@@ -717,8 +717,6 @@ static int tas2781_runtime_suspend(struct device *dev)
 		tas_priv->tasdevice[i].cur_conf = -1;
 	}
 
-	regcache_cache_only(tas_priv->regmap, true);
-	regcache_mark_dirty(tas_priv->regmap);
 
 	mutex_unlock(&tas_priv->codec_lock);
 
@@ -730,20 +728,11 @@ static int tas2781_runtime_resume(struct device *dev)
 	struct tasdevice_priv *tas_priv = dev_get_drvdata(dev);
 	unsigned long calib_data_sz =
 		tas_priv->ndev * TASDEVICE_SPEAKER_CALIBRATION_SIZE;
-	int ret;
 
 	dev_dbg(tas_priv->dev, "Runtime Resume\n");
 
 	mutex_lock(&tas_priv->codec_lock);
 
-	regcache_cache_only(tas_priv->regmap, false);
-	ret = regcache_sync(tas_priv->regmap);
-	if (ret) {
-		dev_err(tas_priv->dev,
-			"Failed to restore register cache: %d\n", ret);
-		goto out;
-	}
-
 	tasdevice_prmg_load(tas_priv, tas_priv->cur_prog);
 
 	/* If calibrated data occurs error, dsp will still works with default
@@ -752,10 +741,9 @@ static int tas2781_runtime_resume(struct device *dev)
 	if (tas_priv->cali_data.total_sz > calib_data_sz)
 		tas2781_apply_calib(tas_priv);
 
-out:
 	mutex_unlock(&tas_priv->codec_lock);
 
-	return ret;
+	return 0;
 }
 
 static int tas2781_system_suspend(struct device *dev)
@@ -770,10 +758,7 @@ static int tas2781_system_suspend(struct device *dev)
 		return ret;
 
 	/* Shutdown chip before system suspend */
-	regcache_cache_only(tas_priv->regmap, false);
 	tasdevice_tuning_switch(tas_priv, 1);
-	regcache_cache_only(tas_priv->regmap, true);
-	regcache_mark_dirty(tas_priv->regmap);
 
 	/*
 	 * Reset GPIO may be shared, so cannot reset here.

sound/soc/codecs/tas2781-comlib.c

@@ -39,7 +39,7 @@ static const struct regmap_range_cfg tasdevice_ranges[] = {
 static const struct regmap_config tasdevice_regmap = {
 	.reg_bits = 8,
 	.val_bits = 8,
-	.cache_type = REGCACHE_RBTREE,
+	.cache_type = REGCACHE_NONE,
 	.ranges = tasdevice_ranges,
 	.num_ranges = ARRAY_SIZE(tasdevice_ranges),
 	.max_register = 256 * 128,