linux-kernel - [PATCH for-6.10 2/2] ASoC: cs35l56: Limit Speaker Volume to +12dB maximum

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Message-ID: <20240722102600.37931-3-rf@opensource.cirrus.com>
Date: Mon, 22 Jul 2024 11:26:00 +0100
From: Richard Fitzgerald <rf@...nsource.cirrus.com>
To: <stable@...r.kernel.org>
CC: <linux-kernel@...r.kernel.org>, <linux-sound@...r.kernel.org>,
        <alsa-devel@...a-project.org>, <patches@...nsource.cirrus.com>
Subject: [PATCH for-6.10 2/2] ASoC: cs35l56: Limit Speaker Volume to +12dB maximum

[ Upstream commit 244389bd42870640c4b5ef672a360da329b579ed ]

Change CS35L56_MAIN_RENDER_USER_VOLUME_MAX to 48, to limit the maximum
value of the Speaker Volume control to +12dB. The minimum value is
unchanged so that the default 0dB has the same integer control value.

The original maximum of 400 (+100dB) was the largest value that can be
mathematically handled by the DSP. The actual maximum amplification is
+12dB.

Backport Note:
Identical to upstream commit. This was originally thought to be only a
cosmetic issue (the user can simply reduce the volume) but for some complex
audio topologies with SOF Audio DSP + CS42L43 + multiple CS35L56 it has 
turned out to be not obvious to the user what the problem actually is and
what to do to fix it. As support for these topologies went into 6.10 we
would like this commit to be backported into 6.10.

Signed-off-by: Richard Fitzgerald <rf@...nsource.cirrus.com>
Link: https://patch.msgid.link/20240703095517.208077-3-rf@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@...nel.org>
---
 include/sound/cs35l56.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/sound/cs35l56.h b/include/sound/cs35l56.h
index 1a3c6f66f620..dc627ebf01df 100644
--- a/include/sound/cs35l56.h
+++ b/include/sound/cs35l56.h
@@ -209,7 +209,7 @@

 /* CS35L56_MAIN_RENDER_USER_VOLUME */
 #define CS35L56_MAIN_RENDER_USER_VOLUME_MIN		-400
-#define CS35L56_MAIN_RENDER_USER_VOLUME_MAX		400
+#define CS35L56_MAIN_RENDER_USER_VOLUME_MAX		48
 #define CS35L56_MAIN_RENDER_USER_VOLUME_MASK		0x0000FFC0
 #define CS35L56_MAIN_RENDER_USER_VOLUME_SHIFT		6
 #define CS35L56_MAIN_RENDER_USER_VOLUME_SIGNBIT		9
-- 
2.39.2