[alsa-devel] snd_hdac_device_unregister is called twice on ASoC driver

[Liao, Bard]

Hi Takashi and all,

We meet a problem that snd_hdac_device_unregister will be called twice
on ASoC driver. We will call snd_hdac_ext_bus_device_init ->
snd_hdac_device_register and snd_hdac_ext_bus_device_remove ->
snd_hdac_device_unregister on ASoC driver. It looks even to me.
However, hdac_hda_codec_probe will call snd_hda_codec_device_new
to create a hda codec device. And it will assign snd_hda_codec_dev_free
to the .dev_free ops where snd_hdac_device_unregister will be called.
That's why snd_hdac_device_unregister will be call twice on ASoC driver.
Below patch can "fix" this issue, but I don't know if it is the right way
to fix it. Could you take a look and give me some advice?

--- a/sound/pci/hda/hda_codec.c
+++ b/sound/pci/hda/hda_codec.c
@@ -841,7 +841,13 @@ static int snd_hda_codec_dev_free(struct snd_device *device)
        struct hda_codec *codec = device->device_data;

        codec->in_freeing = 1;
-       snd_hdac_device_unregister(&codec->core);
+       /*
+        * snd_hda_codec_device_new() is used by legacy HDA and ASoC driver.
+        * We can't unregister ASoC device since it will be unregistered in
+        * snd_hdac_ext_bus_device_remove().
+        */
+       if (codec->core.type == HDA_DEV_LEGACY)
+               snd_hdac_device_unregister(&codec->core);
        codec_display_power(codec, false);
        put_device(hda_codec_dev(codec));
        return 0;

--- a/sound/soc/codecs/hdac_hda.c
+++ b/sound/soc/codecs/hdac_hda.c
@@ -328,6 +328,12 @@ static int hdac_hda_codec_probe(struct snd_soc_component *component)
                dev_err(&hdev->dev, "failed to create hda codec %d\n", ret);
                goto error_no_pm;
        }
+       /*
+        * Overwrite type to HDA_DEV_ASOC since it is a ASoC driver
+        * hda_codec.c will check this flag to determine if unregister
+        * device is needed.
+        */
+       hdev->type = HDA_DEV_ASOC;

        /*
         * snd_hda_codec_device_new decrements the usage count so call get pm