[alsa-devel] Linux Kernel-3.5 crashed as dapm is not supported by codec

Mark Brown broonie at opensource.wolfsonmicro.com
Wed Nov 7 15:56:07 CET 2012

On Wed, Nov 07, 2012 at 11:02:21AM +0530, Rajeev kumar wrote:

> Turn on logging does not helping in giving any extra information in
> this case. Backtracing the code gives me the line number. Please
> find below the information.

Perhaps if you were to share the logging someone might spot something,
or perhaps if you thought about the logging in more detail...

> static void soc_dapm_shutdown_codec(struct snd_soc_dapm_context *dapm)
> 3540 {
> 3541         struct snd_soc_dapm_widget *w;
> 3542         LIST_HEAD(down_list);
> 3543         int powerdown = 0;
> 3544
> 3545         list_for_each_entry(w, &dapm->card->widgets, list) {
> 3546                 if (w->dapm != dapm)
> 3547                         continue;
> 3548                 if (w->power) {
> 3549                         dapm_seq_insert(w, &down_list, false);
> 3550                         w->power = 0;
> 3551                         powerdown = 1;
> 3552                 }
> 3553         }

> If you check line number 3545, it is trying to get widget from card.
> and the system get crashed as there is no entry for dapm in the card.

Your analysis does not appear to correspond to the code.  The DAPM
context is being used to find the card here, not the other way around as
you say.  How have we managed to get an active DAPM context which isn't
part of a card?

> As I mentioned previously, I have provided widgets support only at
> codec level not at platform/machine level. So extracting widgets
> from card may create an issue.

> Note:
> Just to make an experiment, I have added a single widget in machine
> driver then also I am getting the same crash log.

So if you've tested this and found that this is not related to having
widgets in the card what is making you continually mention that you
don't have widgets in the card?  Having no widgets outside the CODEC is
totally normal.
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