linux-kernel - [PATCH v3 6/6] ASoC: amd: ps: Add a module parameter to influence pdm

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Message-ID: <20230131184653.10216-7-mario.limonciello@amd.com>
Date:   Tue, 31 Jan 2023 12:46:52 -0600
From:   Mario Limonciello <mario.limonciello@....com>
To:     Jaroslav Kysela <jkysela@...hat.com>,
        Mukunda Vijendar <Vijendar.Mukunda@....com>,
        Saba Kareem Syed <Syed.SabaKareem@....com>,
        <linux-kernel@...r.kernel.org>
CC:     Pananchikkal Renjith <Renjith.Pananchikkal@....com>,
        Mark Pearson <mpearson@...ovo.com>,
        Mario Limonciello <mario.limonciello@....com>,
        "Liam Girdwood" <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>,
        "Jaroslav Kysela" <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>,
        <alsa-devel@...a-project.org>
Subject: [PATCH v3 6/6] ASoC: amd: ps: Add a module parameter to influence pdm_gain

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: Mario Limonciello <mario.limonciello@....com>
---
v2->v3:
 * Use clamp() and clear bits appropriately
v1->v2:
 * Add a guard for values > 3 to overflow the FIELD_PREP
 * Clear ACP_WOV_GAIN_CONTROL before setting it
---
 sound/soc/amd/ps/acp63.h      | 2 +-
 sound/soc/amd/ps/ps-pdm-dma.c | 8 +++++++-
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/sound/soc/amd/ps/acp63.h b/sound/soc/amd/ps/acp63.h
index bae8288d8231c..bed4d51e226a5 100644
--- a/sound/soc/amd/ps/acp63.h
+++ b/sound/soc/amd/ps/acp63.h
@@ -30,7 +30,7 @@
 #define ACP_ERROR_STAT	29
 #define PDM_DECIMATION_FACTOR	2
 #define ACP_PDM_CLK_FREQ_MASK	7
-#define ACP_WOV_MISC_CTRL_MASK	0x18
+#define ACP_WOV_GAIN_CONTROL	GENMASK(4, 3)
 #define ACP_PDM_ENABLE		1
 #define ACP_PDM_DISABLE		0
 #define ACP_PDM_DMA_EN_STATUS	2
diff --git a/sound/soc/amd/ps/ps-pdm-dma.c b/sound/soc/amd/ps/ps-pdm-dma.c
index eea71a9d2ef1a..91f1631f42c6b 100644
--- a/sound/soc/amd/ps/ps-pdm-dma.c
+++ b/sound/soc/amd/ps/ps-pdm-dma.c
@@ -7,6 +7,7 @@
 
 #include <linux/platform_device.h>
 #include <linux/module.h>
+#include <linux/bitfield.h>
 #include <linux/err.h>
 #include <linux/io.h>
 #include <sound/pcm_params.h>
@@ -18,6 +19,10 @@
 
 #define DRV_NAME "acp_ps_pdm_dma"
 
+static int pdm_gain = 3;
+module_param(pdm_gain, int, 0644);
+MODULE_PARM_DESC(pdm_gain, "Gain control (0-3)");
+
 static const struct snd_pcm_hardware acp63_pdm_hardware_capture = {
 	.info = SNDRV_PCM_INFO_INTERLEAVED |
 		SNDRV_PCM_INFO_BLOCK_TRANSFER |
@@ -55,7 +60,8 @@ static void acp63_enable_pdm_clock(void __iomem *acp_base)
 
 	acp63_writel(pdm_clk_enable, acp_base + ACP_WOV_CLK_CTRL);
 	pdm_ctrl = acp63_readl(acp_base + ACP_WOV_MISC_CTRL);
-	pdm_ctrl |= ACP_WOV_MISC_CTRL_MASK;
+	pdm_ctrl &= ~ACP_WOV_GAIN_CONTROL;
+	pdm_ctrl |= FIELD_PREP(ACP_WOV_GAIN_CONTROL, clamp(pdm_gain, 0, 3));
 	acp63_writel(pdm_ctrl, acp_base + ACP_WOV_MISC_CTRL);
 }
 
-- 
2.34.1