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

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

[Venkata Prasad Potturu]

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@amd.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

Re: [PATCH] ASoC: amd: acp: Adjust pdm dmic gain using module parameter

[Greg KH]

On Mon, Jul 28, 2025 at 03:12:27PM +0530, Venkata Prasad Potturu wrote:
> 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@amd.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)");

This is not the 1990's, please do not add new module parameters, it will
not work for modern systems and is a horrible thing to attempt to
support over time :(

Please do this properly, with a per-device setting.

thanks,

greg k-h

Re: [PATCH] ASoC: amd: acp: Adjust pdm dmic gain using module parameter

[Mario Limonciello]

On 7/28/2025 4:22 PM, Greg KH wrote:
> On Mon, Jul 28, 2025 at 03:12:27PM +0530, Venkata Prasad Potturu wrote:
>> 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@amd.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)");
> 
> This is not the 1990's, please do not add new module parameters, it will
> not work for modern systems and is a horrible thing to attempt to
> support over time :(
> 
> Please do this properly, with a per-device setting.
> 
> thanks,
> 
> greg k-h

As the main purpose for this parameter is for being able to tune whether 
the property is correct, how about adding a debugfs file instead?

AFAICT it should just be a single register write, so debugfs to read 
current value and write the debugging value seems pretty straightforward.

Re: [PATCH] ASoC: amd: acp: Adjust pdm dmic gain using module parameter

[Mark Brown]

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On Tue, Jul 29, 2025 at 11:34:59AM +0530, Mario Limonciello wrote:
> On 7/28/2025 4:22 PM, Greg KH wrote:
> > On Mon, Jul 28, 2025 at 03:12:27PM +0530, Venkata Prasad Potturu wrote:

> > >   * 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.

> > Please do this properly, with a per-device setting.

> As the main purpose for this parameter is for being able to tune whether the
> property is correct, how about adding a debugfs file instead?

> AFAICT it should just be a single register write, so debugfs to read current
> value and write the debugging value seems pretty straightforward.

Or you could just go direct to making it user tunable like a normal gain
control?

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Re: [PATCH] ASoC: amd: acp: Adjust pdm dmic gain using module parameter

[Greg KH]

On Mon, Jul 28, 2025 at 03:12:27PM +0530, Venkata Prasad Potturu wrote:
> 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.

Note, you can not break a user/kernel api like this once you introduce
it, so be VERY careful (yet another reason for it to NOT be a module
parameter...)