Re: [alsa-devel] simple-audio-card with omap4-dmic

On 03/06/15 16:37, Jack Mitchell wrote:

I'm currently working with a PandaBoard clone (OMAP44xx) which doesn't have the usual twl6040 codec, however I would like to attach a digital microphone directly into the OMAP.

I have added the following to my device tree:

    sound {
            compatible = "simple-audio-card";
            simple-audio-card,name = "dmic-card";

            simple-audio-card,format = "pdm";

            status = "okay";

            simple-audio-card,dai-link@0 {
                    cpu {
                            sound-dai = <&dmic>;
                    };

                    codec {
                            sound-dai = <&dmic_codec>;
                    };
            };
    };

    dmic_codec: dmic_codec {
            #sound-dai-cells = <0>;
            compatible = "linux,dmic-codec";
    };

and created a small patch to allow the generic dmic-hifi codec to be instantiated from device tree.

diff --git a/sound/soc/codecs/dmic.c b/sound/soc/codecs/dmic.c index fde5325..67b9198 100644 --- a/sound/soc/codecs/dmic.c +++ b/sound/soc/codecs/dmic.c @@ -69,11 +69,18 @@ static int dmic_dev_remove(struct platform_device *pdev) return 0; }

-MODULE_ALIAS("platform:dmic-codec"); +#ifdef CONFIG_OF +static const struct of_device_id dmic_dt_ids[] = {

•    { .compatible = "linux,dmic-codec", },
  

•    { }
  

+}; +MODULE_DEVICE_TABLE(of, dmic_dt_ids); +#endif

static struct platform_driver dmic_driver = { .driver = { .name = "dmic-codec",

•           .of_match_table = of_match_ptr(dmic_dt_ids),
    },
    .probe = dmic_dev_probe,
    .remove = dmic_dev_remove,
  

@@ -81,6 +88,7 @@ static struct platform_driver dmic_driver = {

module_platform_driver(dmic_driver);

+MODULE_ALIAS("platform:dmic-codec"); MODULE_DESCRIPTION("Generic DMIC driver"); MODULE_AUTHOR("Liam Girdwood lrg@slimlogic.co.uk"); MODULE_LICENSE("GPL");

However, no soundcards get loaded, and I don't get error or warnings in dmesg, so I'm at a bit of a loss at where I'm going wrong. Can anybody see any glaring mistakes? I know the driver is definitely getting loaded as I have seen errors relating to me not specifying the sound-dai-cells from the simple-audio-card driver.

Any ideas would be greatly recieved!

Cheers,

Ok, playing with this a bit more and I find if I manually modprobe snd-soc-dmic then it fires into life. There are other problems with capturing but I'll fight those myself for a bit first.