[RFC,v2,REPOST,2/8] ASoC: davinci-evm: Add named clock reference to DT bindings

Commit Message

Jyri Sarha Dec. 20, 2013, 10:38 a.m. UTC

The referenced clock is used to get codec clock rate and the clock is
disabled and enabled in startup and shutdown snd_soc_ops call
backs. The change is also documented in DT bindigs document.

Signed-off-by: Jyri Sarha <[e-mail]>
cc: [e-mail]
---
 .../bindings/sound/davinci-evm-audio.txt           |    9 ++-
 sound/soc/davinci/davinci-evm.c                    |   60 +++++++++++++++++++-
 2 files changed, 66 insertions(+), 3 deletions(-)

Comments

Mark Brown Dec. 31, 2013, 1:16 p.m. UTC | #1

On Fri, Dec 20, 2013 at 12:38:27PM +0200, Jyri Sarha wrote:

> +static int evm_startup(struct snd_pcm_substream *substream)
> +{
> +	struct snd_soc_pcm_runtime *rtd = substream->private_data;
> +	struct snd_soc_card *soc_card = rtd->codec->card;
> +	struct clk *mclk = ((struct snd_soc_card_drvdata_davinci *)
> +			    snd_soc_card_get_drvdata(soc_card))->mclk;

Why do you need to cast away void?  Ths indicates something is going
wrong here though I can't see what.

> +	mclk = of_clk_get_by_name(np, "ti,codec-clock");
> +	if (PTR_ERR(mclk) == -EPROBE_DEFER) {
> +		return -EPROBE_DEFER;
> +	} else if (IS_ERR(mclk)) {
> +		dev_dbg(&pdev->dev, "Codec clock not found.\n");
> +		mclk = NULL;
> +	}

The driver will unconditionally enable and disable the clock which I'd
not expect to work well if we got an error, I'd expect either NULL checks 
on use or a fixed clock to be registered from code in the case where
we're using the old binding.

I'd also expect to see devm_clk_get() used here, with the standard
clock-names based lookup from DT.

Jyri Sarha Jan. 15, 2014, 11:12 a.m. UTC | #2

On 12/31/2013 03:16 PM, Mark Brown wrote:
> On Fri, Dec 20, 2013 at 12:38:27PM +0200, Jyri Sarha wrote:
>
>> +static int evm_startup(struct snd_pcm_substream *substream)
>> +{
>> +	struct snd_soc_pcm_runtime *rtd = substream->private_data;
>> +	struct snd_soc_card *soc_card = rtd->codec->card;
>> +	struct clk *mclk = ((struct snd_soc_card_drvdata_davinci *)
>> +			    snd_soc_card_get_drvdata(soc_card))->mclk;
>
> Why do you need to cast away void?  Ths indicates something is going
> wrong here though I can't see what.

I'll fix that.

>> +	mclk = of_clk_get_by_name(np, "ti,codec-clock");
>> +	if (PTR_ERR(mclk) == -EPROBE_DEFER) {
>> +		return -EPROBE_DEFER;
>> +	} else if (IS_ERR(mclk)) {
>> +		dev_dbg(&pdev->dev, "Codec clock not found.\n");
>> +		mclk = NULL;
>> +	}
>
> The driver will unconditionally enable and disable the clock which I'd
> not expect to work well if we got an error, I'd expect either NULL checks
> on use or a fixed clock to be registered from code in the case where
> we're using the old binding.
>

In the drivers/clk/clk.c the clk == NULL is always checked before using 
the pointer. However, adding NULL checks would save couple of 
lock-unlock cycles. I'll add them.

> I'd also expect to see devm_clk_get() used here, with the standard
> clock-names based lookup from DT.
>

I'll fix that.

Best regards,
Jyri
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to [e-mail]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Patch

diff --git a/Documentation/devicetree/bindings/sound/davinci-evm-audio.txt b/Documentation/devicetree/bindings/sound/davinci-evm-audio.txt
index 865178d..4aa00f6 100644
--- a/Documentation/devicetree/bindings/sound/davinci-evm-audio.txt
+++ b/Documentation/devicetree/bindings/sound/davinci-evm-audio.txt
@@ -5,12 +5,19 @@  Required properties:
 - ti,model : The user-visible name of this sound complex.
 - ti,audio-codec : The phandle of the TLV320AIC3x audio codec
 - ti,mcasp-controller : The phandle of the McASP controller
-- ti,codec-clock-rate : The Codec Clock rate (in Hz) applied to the Codec
 - ti,audio-routing : A list of the connections between audio components.
   Each entry is a pair of strings, the first being the connection's sink,
   the second being the connection's source. Valid names for sources and
   sinks are the codec's pins, and the jacks on the board:
 
+Optional properties:
+- ti,codec-clock-rate : The Codec Clock rate (in Hz) applied to the Codec.
+- clocks : Reference to the clock used as codec clock
+- clock-names : The codec clock should be named "ti,codec-clock"
+- Either codec-clock-rate or the codec-clock reference has to be defined. If
+  the both are defined the driver attempts to set referenced clock to the
+  defined rate and takes the rate from the clock reference.
+
   Board connectors:
 
   * Headphone Jack
diff --git a/sound/soc/davinci/davinci-evm.c b/sound/soc/davinci/davinci-evm.c
index 70ff377..b28c9fd 100644
--- a/sound/soc/davinci/davinci-evm.c
+++ b/sound/soc/davinci/davinci-evm.c
@@ -17,6 +17,7 @@ 
 #include <linux/platform_data/edma.h>
 #include <linux/i2c.h>
 #include <linux/of_platform.h>
+#include <linux/clk.h>
 #include <sound/core.h>
 #include <sound/pcm.h>
 #include <sound/soc.h>
@@ -30,9 +31,30 @@ 
 #include "davinci-i2s.h"
 
 struct snd_soc_card_drvdata_davinci {
+	struct clk *mclk;
 	unsigned sysclk;
 };
 
+static int evm_startup(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_card *soc_card = rtd->codec->card;
+	struct clk *mclk = ((struct snd_soc_card_drvdata_davinci *)
+			    snd_soc_card_get_drvdata(soc_card))->mclk;
+
+	return clk_prepare_enable(mclk);
+}
+
+static void evm_shutdown(struct snd_pcm_substream *substream)
+{
+	struct snd_soc_pcm_runtime *rtd = substream->private_data;
+	struct snd_soc_card *soc_card = rtd->codec->card;
+	struct clk *mclk = ((struct snd_soc_card_drvdata_davinci *)
+			    snd_soc_card_get_drvdata(soc_card))->mclk;
+
+	clk_disable_unprepare(mclk);
+}
+
 static int evm_hw_params(struct snd_pcm_substream *substream,
 			 struct snd_pcm_hw_params *params)
 {
@@ -59,6 +81,8 @@  static int evm_hw_params(struct snd_pcm_substream *substream,
 }
 
 static struct snd_soc_ops evm_ops = {
+	.startup = evm_startup,
+	.shutdown = evm_shutdown,
 	.hw_params = evm_hw_params,
 };
 
@@ -348,6 +372,7 @@  static int davinci_evm_probe(struct platform_device *pdev)
 		of_match_device(of_match_ptr(davinci_evm_dt_ids), &pdev->dev);
 	struct snd_soc_dai_link *dai = (struct snd_soc_dai_link *) match->data;
 	struct snd_soc_card_drvdata_davinci *drvdata = NULL;
+	struct clk *mclk;
 	int ret = 0;
 
 	evm_soc_card.dai_link = dai;
@@ -367,13 +392,38 @@  static int davinci_evm_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	mclk = of_clk_get_by_name(np, "ti,codec-clock");
+	if (PTR_ERR(mclk) == -EPROBE_DEFER) {
+		return -EPROBE_DEFER;
+	} else if (IS_ERR(mclk)) {
+		dev_dbg(&pdev->dev, "Codec clock not found.\n");
+		mclk = NULL;
+	}
+
 	drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
 	if (!drvdata)
 		return -ENOMEM;
 
+	drvdata->mclk = mclk;
+
 	ret = of_property_read_u32(np, "ti,codec-clock-rate", &drvdata->sysclk);
-	if (ret < 0)
-		return -EINVAL;
+
+	if (ret < 0) {
+		if (!drvdata->mclk) {
+			dev_err(&pdev->dev,
+				"No clock or clock rate defined.\n");
+			return -EINVAL;
+		}
+		drvdata->sysclk = clk_get_rate(drvdata->mclk);
+	} else if (drvdata->mclk) {
+		unsigned int requestd_rate = drvdata->sysclk;
+		clk_set_rate(drvdata->mclk, drvdata->sysclk);
+		drvdata->sysclk = clk_get_rate(drvdata->mclk);
+		if (drvdata->sysclk != requestd_rate)
+			dev_warn(&pdev->dev,
+				 "Could not get requested rate %u using %u.\n",
+				 requestd_rate, drvdata->sysclk);
+	}
 
 	snd_soc_card_set_drvdata(&evm_soc_card, drvdata);
 	ret = devm_snd_soc_register_card(&pdev->dev, &evm_soc_card);
@@ -387,6 +437,12 @@  static int davinci_evm_probe(struct platform_device *pdev)
 static int davinci_evm_remove(struct platform_device *pdev)
 {
 	struct snd_soc_card *card = platform_get_drvdata(pdev);
+	struct snd_soc_card_drvdata_davinci *drvdata =
+		(struct snd_soc_card_drvdata_davinci *)
+		snd_soc_card_get_drvdata(card);
+
+	if (drvdata->mclk)
+		clk_put(drvdata->mclk);
 
 	snd_soc_unregister_card(card);