linux-kernel - [PATCH] ASoC: amd: acp: Adjust pdm dmic gain using module parameter

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Message-ID: <20250728094243.3824450-1-venkataprasad.potturu@amd.com>
Date: Mon, 28 Jul 2025 15:12:27 +0530
From: Venkata Prasad Potturu <venkataprasad.potturu@....com>
To: <broonie@...nel.org>, <alsa-devel@...a-project.org>
CC: <Vijendar.Mukunda@....com>, <Basavaraj.Hiregoudar@....com>,
	<Sunil-kumar.Dommati@....com>, <syed.sabakareem@....com>, "Venkata Prasad
 Potturu" <venkataprasad.potturu@....com>, Liam Girdwood
	<lgirdwood@...il.com>, Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai
	<tiwai@...e.com>, Mario Limonciello <mario.limonciello@....com>, "Peter
 Zijlstra" <peterz@...radead.org>, Greg KH <gregkh@...uxfoundation.org>, "open
 list:SOUND - SOC LAYER / DYNAMIC AUDIO POWER MANAGEM..."
	<linux-sound@...r.kernel.org>, open list <linux-kernel@...r.kernel.org>
Subject: [PATCH] ASoC: amd: acp: Adjust pdm dmic gain using module parameter

Adjust pdm dimc gain value using module param.
In case of regressions for any users that the new pdm_gain value is
too high and for additional debugging, introduce a module parameter
that would let them configure it.

This parameter should be removed in the future:
 * If it's determined that the parameter is not needed, just hardcode
   the correct value as before
 * If users do end up using it to debug and report different values
   we should introduce a config knob that can have policy set by ucm.

Signed-off-by: Venkata Prasad Potturu <venkataprasad.potturu@....com>
---
 sound/soc/amd/acp/acp-legacy-common.c | 3 ++-
 sound/soc/amd/acp/acp-pdm.c           | 3 ++-
 sound/soc/amd/acp/amd.h               | 6 +++++-
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/sound/soc/amd/acp/acp-legacy-common.c b/sound/soc/amd/acp/acp-legacy-common.c
index 57982d057c3a..dd804fb95790 100644
--- a/sound/soc/amd/acp/acp-legacy-common.c
+++ b/sound/soc/amd/acp/acp-legacy-common.c
@@ -173,7 +173,8 @@ static void set_acp_pdm_clk(struct snd_pcm_substream *substream,
 	/* Enable default ACP PDM clk */
 	writel(PDM_CLK_FREQ_MASK, chip->base + ACP_WOV_CLK_CTRL);
 	pdm_ctrl = readl(chip->base + ACP_WOV_MISC_CTRL);
-	pdm_ctrl |= PDM_MISC_CTRL_MASK;
+	pdm_ctrl &= ~ACP_WOV_GAIN_CONTROL;
+	pdm_ctrl |= FIELD_PREP(ACP_WOV_GAIN_CONTROL, clamp(pdm_gain, 0, 3));
 	writel(pdm_ctrl, chip->base + ACP_WOV_MISC_CTRL);
 	set_acp_pdm_ring_buffer(substream, dai);
 }
diff --git a/sound/soc/amd/acp/acp-pdm.c b/sound/soc/amd/acp/acp-pdm.c
index 1bfc34c2aa53..ffb622a7a69a 100644
--- a/sound/soc/amd/acp/acp-pdm.c
+++ b/sound/soc/amd/acp/acp-pdm.c
@@ -38,7 +38,8 @@ static int acp_dmic_prepare(struct snd_pcm_substream *substream,
 	/* Enable default DMIC clk */
 	writel(PDM_CLK_FREQ_MASK, chip->base + ACP_WOV_CLK_CTRL);
 	dmic_ctrl = readl(chip->base + ACP_WOV_MISC_CTRL);
-	dmic_ctrl |= PDM_MISC_CTRL_MASK;
+	dmic_ctrl &= ~ACP_WOV_GAIN_CONTROL;
+	dmic_ctrl |= FIELD_PREP(ACP_WOV_GAIN_CONTROL, clamp(pdm_gain, 0, 3));
 	writel(dmic_ctrl, chip->base + ACP_WOV_MISC_CTRL);
 
 	period_bytes = frames_to_bytes(substream->runtime,
diff --git a/sound/soc/amd/acp/amd.h b/sound/soc/amd/acp/amd.h
index cb8d97122f95..f2567e06ccd3 100644
--- a/sound/soc/amd/acp/amd.h
+++ b/sound/soc/amd/acp/amd.h
@@ -130,7 +130,7 @@
 #define PDM_DMA_INTR_MASK       0x10000
 #define PDM_DEC_64              0x2
 #define PDM_CLK_FREQ_MASK       0x07
-#define PDM_MISC_CTRL_MASK      0x10
+#define ACP_WOV_GAIN_CONTROL	GENMASK(4, 3)
 #define PDM_ENABLE              0x01
 #define PDM_DISABLE             0x00
 #define DMA_EN_MASK             0x02
@@ -138,6 +138,10 @@
 #define PDM_TIMEOUT             1000
 #define ACP_REGION2_OFFSET      0x02000000
 
+static int pdm_gain = 3;
+module_param(pdm_gain, int, 0644);
+MODULE_PARM_DESC(pdm_gain, "Gain control (0-3)");
+
 struct acp_chip_info {
 	char *name;		/* Platform name */
 	struct resource *res;
-- 
2.43.0