[PATCH] ASoC: pxa2xx-ac97: fix oops when codec_driver probe runs

[PATCH] ASoC: pxa2xx-ac97: fix oops when codec_driver probe runs

[Mike Dunn]

This patch fixes a kernel oops that occurs when the snd_soc_codec_driver probe
function runs.  The exception occurs when the codec calls soc_ac97_ops.reset().
The pxa2xx-ac97's clocks have not been initialized at this point, but the cpu's
reset function (pxa_ac97_cold_pxa27x()) expects them to be, resulting in a NULL
pointer dereference in the pxa's clk_enable().

The pxa2xx-ac97's clocks are initialized in pxa2xx_ac97_hw_probe().  To ensure
that the clocks are initialized when the codec_driver probe runs, the calls to
pxa2xx_ac97_hw_{probe,remove}() are moved from the cpu's dai_driver probe/remove
functions to those of its platform_driver.  This is necessary because
snd_soc_instantiate_card() always calls the codec_driver probe before any of the
dai_drivers' probes.

This change leaves nothing in the cpu's dai_driver probe/remove functions, so
those functions are eliminated.

Tested on the pxa27x; palmtreo680 machine using the wm9712 codec.

Signed-off-by: Mike Dunn <mikedunn@newsguy.com>
---

I'm new to the ASoC code.  Experts, please have a look.  Thanks!

 sound/soc/pxa/pxa2xx-ac97.c |   38 +++++++++++++++++++-------------------
 1 files changed, 19 insertions(+), 19 deletions(-)

diff --git a/sound/soc/pxa/pxa2xx-ac97.c b/sound/soc/pxa/pxa2xx-ac97.c
index 4b0a009..940e9f4 100644
--- a/sound/soc/pxa/pxa2xx-ac97.c
+++ b/sound/soc/pxa/pxa2xx-ac97.c
@@ -104,17 +104,6 @@ static int pxa2xx_ac97_resume(struct snd_soc_dai *dai)
 #define pxa2xx_ac97_resume	NULL
 #endif
 
-static int pxa2xx_ac97_probe(struct snd_soc_dai *dai)
-{
-	return pxa2xx_ac97_hw_probe(to_platform_device(dai->dev));
-}
-
-static int pxa2xx_ac97_remove(struct snd_soc_dai *dai)
-{
-	pxa2xx_ac97_hw_remove(to_platform_device(dai->dev));
-	return 0;
-}
-
 static int pxa2xx_ac97_hw_params(struct snd_pcm_substream *substream,
 				 struct snd_pcm_hw_params *params,
 				 struct snd_soc_dai *cpu_dai)
@@ -184,8 +173,6 @@ static struct snd_soc_dai_driver pxa_ac97_dai_driver[] = {
 {
 	.name = "pxa2xx-ac97",
 	.ac97_control = 1,
-	.probe = pxa2xx_ac97_probe,
-	.remove = pxa2xx_ac97_remove,
 	.suspend = pxa2xx_ac97_suspend,
 	.resume = pxa2xx_ac97_resume,
 	.playback = {
@@ -236,21 +223,34 @@ EXPORT_SYMBOL_GPL(soc_ac97_ops);
 
 static int pxa2xx_ac97_dev_probe(struct platform_device *pdev)
 {
+	int ret;
+
 	if (pdev->id != -1) {
 		dev_err(&pdev->dev, "PXA2xx has only one AC97 port.\n");
 		return -ENXIO;
 	}
 
-	/* Punt most of the init to the SoC probe; we may need the machine
-	 * driver to do interesting things with the clocking to get us up
-	 * and running.
-	 */
-	return snd_soc_register_dais(&pdev->dev, pxa_ac97_dai_driver,
-			ARRAY_SIZE(pxa_ac97_dai_driver));
+	ret = snd_soc_register_dais(&pdev->dev, pxa_ac97_dai_driver,
+				    ARRAY_SIZE(pxa_ac97_dai_driver));
+	if (ret < 0) {
+		dev_err(&pdev->dev, "snd_soc_register_dais failed with %d\n",
+			ret);
+		return ret;
+	}
+
+	ret = pxa2xx_ac97_hw_probe(pdev);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "pxa2xx_ac97_hw_probe failed with %d\n",
+			ret);
+		snd_soc_unregister_dais(&pdev->dev,
+					ARRAY_SIZE(pxa_ac97_dai_driver));
+	}
+	return ret;
 }
 
 static int pxa2xx_ac97_dev_remove(struct platform_device *pdev)
 {
+	pxa2xx_ac97_hw_remove(pdev);
 	snd_soc_unregister_dais(&pdev->dev, ARRAY_SIZE(pxa_ac97_dai_driver));
 	return 0;
 }
-- 
1.7.8.6

[PATCH] ASoC: pxa2xx-ac97: fix oops when codec_driver probe runs

[Mark Brown]

On Fri, Dec 28, 2012 at 06:17:55AM -0800, Mike Dunn wrote:

> -	/* Punt most of the init to the SoC probe; we may need the machine
> -	 * driver to do interesting things with the clocking to get us up
> -	 * and running.
> -	 */
> -	return snd_soc_register_dais(&pdev->dev, pxa_ac97_dai_driver,
> -			ARRAY_SIZE(pxa_ac97_dai_driver));
> +	ret = snd_soc_register_dais(&pdev->dev, pxa_ac97_dai_driver,
> +				    ARRAY_SIZE(pxa_ac97_dai_driver));
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "snd_soc_register_dais failed with %d\n",
> +			ret);
> +		return ret;
> +	}
> +
> +	ret = pxa2xx_ac97_hw_probe(pdev);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "pxa2xx_ac97_hw_probe failed with %d\n",
> +			ret);
> +		snd_soc_unregister_dais(&pdev->dev,
> +					ARRAY_SIZE(pxa_ac97_dai_driver));
> +	}
> +	return ret;

We should be doing all resource acquisition before registering the DAIs,
if anything this patch introduces the potential for additional issues
with the clocks not having been acquired before we try to use them in
the sound card.
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