[PATCH 0/3] ASoC: wm8782: Allow higher audio rates

[PATCH 0/3] ASoC: wm8782: Allow higher audio rates

[John Watts]

The wm8782 supports higher audio rates than just 48kHz. This is
configured by setting the FSAMPEN pin on the codec chip.

This patch series introduces the 'max-rate' device tree property
to allow indicating which rates are fully supported by the codec
without accidentally overclocking.

John Watts (3):
  ASoC: wm8782: Handle maximum audio rate at runtime
  ASoC: wm8782: Use max-rate device tree property
  ASoC: dt-bindings: wlf,wm8782: Add max-rate property

 .../devicetree/bindings/sound/wm8782.txt      |  2 +
 sound/soc/codecs/wm8782.c                     | 49 ++++++++++++++-----
 2 files changed, 39 insertions(+), 12 deletions(-)

-- 
2.41.0

[PATCH 1/3] ASoC: wm8782: Handle maximum audio rate at runtime

[John Watts]

The wm8782 supports up to 192kHz audio when pins are set correctly.
Instead of hardcoding which rates are supported enable them all
then refer to a max_rate variable at runtime.

Signed-off-by: John Watts <contact@jookia.org>
---
 sound/soc/codecs/wm8782.c | 45 ++++++++++++++++++++++++++++-----------
 1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/sound/soc/codecs/wm8782.c b/sound/soc/codecs/wm8782.c
index 95ff4339d103..63ab63f3189a 100644
--- a/sound/soc/codecs/wm8782.c
+++ b/sound/soc/codecs/wm8782.c
@@ -23,6 +23,30 @@
 #include <sound/initval.h>
 #include <sound/soc.h>
 
+/* regulator power supply names */
+static const char *supply_names[] = {
+	"Vdda", /* analog supply, 2.7V - 3.6V */
+	"Vdd",  /* digital supply, 2.7V - 5.5V */
+};
+
+struct wm8782_priv {
+	struct regulator_bulk_data supplies[ARRAY_SIZE(supply_names)];
+	int max_rate;
+};
+
+static int wm8782_dai_hw_params(struct snd_pcm_substream *component,
+			    struct snd_pcm_hw_params *params,
+			    struct snd_soc_dai *dai)
+{
+	struct wm8782_priv *priv =
+		snd_soc_component_get_drvdata(dai->component);
+
+	if (params_rate(params) > priv->max_rate)
+		return -EINVAL;
+
+	return 0;
+}
+
 static const struct snd_soc_dapm_widget wm8782_dapm_widgets[] = {
 SND_SOC_DAPM_INPUT("AINL"),
 SND_SOC_DAPM_INPUT("AINR"),
@@ -33,28 +57,22 @@ static const struct snd_soc_dapm_route wm8782_dapm_routes[] = {
 	{ "Capture", NULL, "AINR" },
 };
 
+static const struct snd_soc_dai_ops wm8782_dai_ops = {
+	.hw_params = &wm8782_dai_hw_params,
+};
+
 static struct snd_soc_dai_driver wm8782_dai = {
 	.name = "wm8782",
 	.capture = {
 		.stream_name = "Capture",
 		.channels_min = 2,
 		.channels_max = 2,
-		/* For configurations with FSAMPEN=0 */
-		.rates = SNDRV_PCM_RATE_8000_48000,
+		.rates = SNDRV_PCM_RATE_8000_192000,
 		.formats = SNDRV_PCM_FMTBIT_S16_LE |
 			   SNDRV_PCM_FMTBIT_S20_3LE |
 			   SNDRV_PCM_FMTBIT_S24_LE,
 	},
-};
-
-/* regulator power supply names */
-static const char *supply_names[] = {
-	"Vdda", /* analog supply, 2.7V - 3.6V */
-	"Vdd",  /* digital supply, 2.7V - 5.5V */
-};
-
-struct wm8782_priv {
-	struct regulator_bulk_data supplies[ARRAY_SIZE(supply_names)];
+	.ops = &wm8782_dai_ops,
 };
 
 static int wm8782_soc_probe(struct snd_soc_component *component)
@@ -121,6 +139,9 @@ static int wm8782_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return ret;
 
+	/* For configurations with FSAMPEN=0 */
+	priv->max_rate = 48000;
+
 	return devm_snd_soc_register_component(&pdev->dev,
 			&soc_component_dev_wm8782, &wm8782_dai, 1);
 }
-- 
2.41.0

[PATCH 2/3] ASoC: wm8782: Use max-rate device tree property

[John Watts]

The wm8782 supports rates 96kHz and 192kHz as long as the hardware
is configured properly. Allow this to be specified in the device tree.

Signed-off-by: John Watts <contact@jookia.org>
---
 sound/soc/codecs/wm8782.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/sound/soc/codecs/wm8782.c b/sound/soc/codecs/wm8782.c
index 63ab63f3189a..6a2f29ee897c 100644
--- a/sound/soc/codecs/wm8782.c
+++ b/sound/soc/codecs/wm8782.c
@@ -122,6 +122,7 @@ static const struct snd_soc_component_driver soc_component_dev_wm8782 = {
 static int wm8782_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
+	struct device_node *np = dev->of_node;
 	struct wm8782_priv *priv;
 	int ret, i;
 
@@ -139,9 +140,12 @@ static int wm8782_probe(struct platform_device *pdev)
 	if (ret < 0)
 		return ret;
 
-	/* For configurations with FSAMPEN=0 */
+	/* Assume lowest value by default to avoid inadvertent overclocking */
 	priv->max_rate = 48000;
 
+	if (np)
+		of_property_read_u32(np, "max-rate", &priv->max_rate);
+
 	return devm_snd_soc_register_component(&pdev->dev,
 			&soc_component_dev_wm8782, &wm8782_dai, 1);
 }
-- 
2.41.0

[PATCH 3/3] ASoC: dt-bindings: wlf,wm8782: Add max-rate property

[John Watts]

The WM8782 can safely support rates higher than 48kHz by changing the
value of the FSAMPEN pin.

Allow specifying the maximum support rate the hardware configuration
supports in the device tree.

Signed-off-by: John Watts <contact@jookia.org>
---
 Documentation/devicetree/bindings/sound/wm8782.txt | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/sound/wm8782.txt b/Documentation/devicetree/bindings/sound/wm8782.txt
index 256cdec6ec4d..a68061a3e671 100644
--- a/Documentation/devicetree/bindings/sound/wm8782.txt
+++ b/Documentation/devicetree/bindings/sound/wm8782.txt
@@ -7,6 +7,7 @@ Required properties:
  - compatible  : "wlf,wm8782"
  - Vdda-supply : phandle to a regulator for the analog power supply (2.7V - 5.5V)
  - Vdd-supply  : phandle to a regulator for the digital power supply (2.7V - 3.6V)
+ - max-rate    : max supported audio rate configured by FSAMPEN pin, defaults to 48000
 
 Example:
 
@@ -14,4 +15,5 @@ wm8782: stereo-adc {
 	compatible = "wlf,wm8782";
 	Vdda-supply = <&vdda_supply>;
 	Vdd-supply = <&vdd_supply>;
+	max-rate = <96000>; /* FSAMPEN is 1 */
 };
-- 
2.41.0

Re: [PATCH 3/3] ASoC: dt-bindings: wlf,wm8782: Add max-rate property

[Mark Brown]

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On Fri, Aug 11, 2023 at 08:49:30AM +1000, John Watts wrote:

> + - max-rate    : max supported audio rate configured by FSAMPEN pin, defaults to 48000

This seems like a cumbersome and error prone way to configure this - why
not just have the binding specify the state of the pin?  That's just a
boolean high/low whereas this requires getting the rate right and then
having the driver validate it.

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Re: [PATCH 3/3] ASoC: dt-bindings: wlf,wm8782: Add max-rate property

[John Watts]

On Fri, Aug 11, 2023 at 02:59:35PM +0100, Mark Brown wrote:
> On Fri, Aug 11, 2023 at 08:49:30AM +1000, John Watts wrote:
> 
> > + - max-rate    : max supported audio rate configured by FSAMPEN pin, defaults to 48000
> 
> This seems like a cumbersome and error prone way to configure this - why
> not just have the binding specify the state of the pin?  That's just a
> boolean high/low whereas this requires getting the rate right and then
> having the driver validate it.

Hi there, the pin is tristate, Z, 0 and 1. How would that be represented?

John.

Re: [PATCH 3/3] ASoC: dt-bindings: wlf,wm8782: Add max-rate property

[Mark Brown]

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On Sat, Aug 12, 2023 at 12:26:15AM +1000, John Watts wrote:
> On Fri, Aug 11, 2023 at 02:59:35PM +0100, Mark Brown wrote:
> > On Fri, Aug 11, 2023 at 08:49:30AM +1000, John Watts wrote:

> > > + - max-rate    : max supported audio rate configured by FSAMPEN pin, defaults to 48000

> > This seems like a cumbersome and error prone way to configure this - why
> > not just have the binding specify the state of the pin?  That's just a
> > boolean high/low whereas this requires getting the rate right and then
> > having the driver validate it.

> Hi there, the pin is tristate, Z, 0 and 1. How would that be represented?

You'd have to define an enum for that but it does still feel like it
might be easier to work with since it's more direct.

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Re: [PATCH 3/3] ASoC: dt-bindings: wlf,wm8782: Add max-rate property

[John Watts]

On Mon, Aug 14, 2023 at 07:27:04PM +0100, Mark Brown wrote:
> You'd have to define an enum for that but it does still feel like it
> might be easier to work with since it's more direct.

Alright, I'll give it a go in the next version. Thanks for the feedback!

John.

Re: [PATCH 3/3] ASoC: dt-bindings: wlf,wm8782: Add max-rate property

[Rob Herring]

On Mon, Aug 14, 2023 at 4:45 PM John Watts <contact@jookia.org> wrote:
>
> On Mon, Aug 14, 2023 at 07:27:04PM +0100, Mark Brown wrote:
> > You'd have to define an enum for that but it does still feel like it
> > might be easier to work with since it's more direct.
>
> Alright, I'll give it a go in the next version. Thanks for the feedback!

That property will need a vendor prefix as well which was missing here.

Rob