[alsa-devel] [PATCH] ASoC: fsl: imx-wm8962: Set the card owner field

[Fabio Estevam]

From: Fabio Estevam <fabio.estevam at freescale.com>

The following crash happens when trying to unload the snd_soc_imx_wm8962 module
while playback is active:

[  208.666868] Unable to handle kernel paging request at virtc
[  208.674110] pgd = 80004000
[  208.676867] [7f06541c] *pgd=4c334811, *pte=00000000, *ppte=00000000
[  208.683211] Internal error: Oops: 80000007 [#1] SMP ARM
[  208.688445] Modules linked in: snd_soc_wm8962 snd_soc_fsl_ssi snd_soc_imx_audmux imx_pcm_fiq evbug]
...

In order to avoid such problem, fill the card owner field as suggested by
Lars-Peter Clausen:

"But looking at the source it seems that this is a core feature of ALSA and at 
least for the card module itself it will do the ref-counting when a stream is 
started/stopped. And we even support setting the owner of a card in ASoC. 
It's just that pretty much no ASoC card driver bothers to set the owner field
in the snd_soc_card struct. So this particular problem can be fixed by updating
the imx-wm8962 driver to set the owner field."

By doing as suggested, we no longer see the crash when attempting to unload the
snd_soc_imx_wm8962 module while playback is active:

$ modprobe -r snd_soc_imx_wm8962
modprobe: can't unload module snd_soc_imx_wm8962: Resource temporarily 
unavailable

Reported-by: Jiada Wang <jiada_wang at mentor.com>
Suggested-by: Lars-Peter Clausen <lars at metafoo.de>
Signed-off-by: Fabio Estevam <fabio.estevam at freescale.com>
---
 sound/soc/fsl/imx-wm8962.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/sound/soc/fsl/imx-wm8962.c b/sound/soc/fsl/imx-wm8962.c
index 4caacb0..cd146d4 100644
--- a/sound/soc/fsl/imx-wm8962.c
+++ b/sound/soc/fsl/imx-wm8962.c
@@ -257,6 +257,7 @@ static int imx_wm8962_probe(struct platform_device *pdev)
 	if (ret)
 		goto clk_fail;
 	data->card.num_links = 1;
+	data->card.owner = THIS_MODULE;
 	data->card.dai_link = &data->dai;
 	data->card.dapm_widgets = imx_wm8962_dapm_widgets;
 	data->card.num_dapm_widgets = ARRAY_SIZE(imx_wm8962_dapm_widgets);
-- 
1.9.1