[PATCH] ASoC: codecs: lpass-wsa-macro: rewrite the interpolator volume after enabling clocks

[Liviu Nicoara <lnicoara@thinkoid.org>]

Commit 902f497a1ff5 ("ASoC: codecs: lpass-wsa-macro: remove useless
gain read/write sequence") removed the read and write of the digital
volume register in wsa_macro_enable_interpolator(), on the grounds that
writing back the value just read does nothing. The comment above it,
"apply gain after int clk is enabled", was left in place.

On the Dell XPS 13 9345 (X1E80100, four WSA8845 amplifiers on two WSA
macros) the write does something: a volume change made while the path
is idle does not take effect when playback starts. Lowering the digital
volume from 81 to 63 with nothing playing, then playing a test tone,
gave about the same level as before the change. With the rewrite
restored, lowering it from 81 to 69 while idle played audibly quieter,
and restoring 81 while idle brought the level back. Changes made during
playback take effect with or without the rewrite.

This is the behaviour described in commit 46188db080bd ("ASoC: codecs:
lpass-wsa-macro: fix compander volume hack"): "the volume registers
still need to be written after enabling clocks in order for any prior
updates to take effect." The value read comes from the register cache,
so the write pushes the last requested volume to the hardware once its
clock runs.

Restore the rewrite in the interpolator's POST_PMU event only. The mix
path event removed later in the same series is not brought back.

Fixes: 902f497a1ff5 ("ASoC: codecs: lpass-wsa-macro: remove useless gain read/write sequence")
Assisted-by: Claude:claude-opus-5-5
Signed-off-by: Liviu Nicoara <lnicoara@thinkoid.org>
---

Notes:
    Tested on v7.2.6 on the machine above, by listening. This function is
    unchanged between v7.2 and for-next; the driver's clocks moved to the
    PM clock framework in cd054a6e272c after v7.2, which was not tested
    here. Build-tested on broonie/for-next (arm64 defconfig).

 sound/soc/codecs/lpass-wsa-macro.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/soc/codecs/lpass-wsa-macro.c b/sound/soc/codecs/lpass-wsa-macro.c
index 4242366601a5..899c8bee4645 100644
--- a/sound/soc/codecs/lpass-wsa-macro.c
+++ b/sound/soc/codecs/lpass-wsa-macro.c
@@ -1849,6 +1849,7 @@ static int wsa_macro_enable_interpolator(struct snd_soc_dapm_widget *w,
 					 int event)
 {
 	struct snd_soc_component *component = snd_soc_dapm_to_component(w->dapm);
+	unsigned int gain;
 	u16 gain_reg;
 	u16 reg;
 	struct wsa_macro *wsa = snd_soc_component_get_drvdata(component);
@@ -1890,6 +1891,8 @@ static int wsa_macro_enable_interpolator(struct snd_soc_dapm_widget *w,
 					CDC_WSA_RX_PGA_HALF_DB_MASK,
 					CDC_WSA_RX_PGA_HALF_DB_ENABLE);
 		}
+		gain = snd_soc_component_read(component, gain_reg);
+		snd_soc_component_write(component, gain_reg, gain);
 		wsa_macro_config_ear_spkr_gain(component, wsa,
 						event, gain_reg);
 		break;
-- 
2.55.0