Re: [alsa-devel] substream->private_data == NULL in hw_params

At Tue, 17 Jul 2007 03:00:44 +0200, Florian Demski wrote:

Hi there,

after many reboots I finally fixed an error in a driver but I am not sure if there ain't an underlying problem which causes this error.

The initialization is done with

    struct snd_pcm *pcm;
    int err;

    if((err = snd_pcm_new(chip->pod->line6.card, (char 

*)chip->pod->line6.devname, 0, 1, 1, &pcm)) < 0) return err;

    pcm->private_data = chip;
    pcm->private_free = pod_cleanup_pcm;
    chip->pcm = pcm;

However in hw_param, substream->private_data is NULL and I have to get the right value with this construct:

That's weird. substream->private_data is copied from pcm->private_data at snd_pcm_open(), and never changed in another part of PCM core layer. So, my guess is somewhere in your driver overwrites it. Maybe not explicitly.

I'd check each call between open and hw_params, e.g. adding printk appropriately...

Takashi