Re: [alsa-devel] Support two wm8962 codec in i.mx6 board.

18 Mar 2015


      Hi Nicolin,
On Wed, Mar 18, 2015 at 9:33 AM, Nicolin Chen nicoleotsuka@gmail.com wrote:
...
On Wed, Mar 18, 2015 at 09:12:19AM +0800, Shawn Embedded wrote:
...
Yes, it's and old version, without support of device tree.
   For AUDMUX configuration, is the code below enough, snippet 1 and 2?
I think so.
...
And here I have another question about clock source sharing

between the two codecs.
    The two wm8962 codecs use the same clock source from imx6, in my
case, clko, as the code mentioned below,
...
Since the two codecs share the same clock source, clko, and we donot
know when mxc_wm8962_init() and wm8962_clk_enable() will be called by
using the function pointer exactly, do you think it's necessary to
make NULL to init, make wm8962_clk_enable_do_nothing to clock_enable,
and manually calling mxc_wm8962_init() and wm8962_clk_enable() in the
xxx_board_init() function instead?
I don't think you need to change this part.
If donot change it, what will happen to the working codec if the
clock_enable is called caused by stopping the other codec? the working
codec will not be affected?
...
...

In imx-wm8962.c:

static int __devinit imx_wm8962_probe(struct platform_device *pdev)
{
    ....
    imx_audmux_config(src, ext);    // should keep the same, not need
to change, right?
    ....
}
No, you don't need to.
...
But there is a question here.
  How should I track the  card_priv and its copy for the two codecs repectively.
  They are used heavily.
   In order to make the functions run without problems, seems
necessary to differentiate the function call is for which codec of the
two, right?
  The same situation may exist for other just copied global variables
in imx-wm8962.c.
Each dai-link will create an individual sound card during system
boot-up. Use 'aplay -l', you will see they are different devices.
I know what you mean.
   But let me paste a snippet of code here, for two codecs on board,
do'not you think it's necessary to setup 2 structure imx_priv to track
the two codecs respectively?
In imx-wm8962.c
static struct imx_priv card_priv;
static void imx_hifi_shutdown(struct snd_pcm_substream *substream)
{
     struct snd_soc_pcm_runtime *rtd = substream->private_data;
     struct snd_soc_dai *codec_dai = rtd->codec_dai;
     struct imx_priv *priv = &card_priv;
     struct mxc_audio_platform_data *plat = priv->pdev->dev.platform_data;
if (!codec_dai->active)
          plat->clock_enable(0);
return;
}
/*
 * This function will register the snd_soc_pcm_link drivers.
 */
static int __devinit imx_wm8962_probe(struct platform_device *pdev)
{
struct mxc_audio_platform_data *plat = pdev->dev.platform_data;
     struct imx_priv *priv = &card_priv;
     int ret = 0;
priv->pdev = pdev;
imx_audmux_config(plat->src_port, plat->ext_port);
if (plat->init && plat->init()) {
          ret = -EINVAL;
     return ret;
     }
priv->sysclk = plat->sysclk;
priv->sdev.name = "h2w";
     ret = switch_dev_register(&priv->sdev);
     if (ret < 0) {
          ret = -EINVAL;
     return ret;
     }
if (plat->hp_gpio != -1) {
          priv->hp_status = gpio_get_value(plat->hp_gpio);
if (priv->hp_status != plat->hp_active_low)
               switch_set_state(&priv->sdev, 2);
          else
               switch_set_state(&priv->sdev, 0);
     }
     priv->first_stream = NULL;
     priv->second_stream = NULL;
return ret;
}
Thank you.
Best Regards,
Shawn