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SubjectHelp request - ASoC recursion issue
Hi Mark,

I was wondering if I may bother you for some help. I've been having
serious issues with testing the new mop500 sound system you have in your
ASoC for-next branch. I've fixed a few issues and will be submitting
patches shortly. The most serious issue I came across was with
recursion. Let me show you:

So here we setup the power_check function pointer with
'dapm_supply_check_power()'.

> static struct snd_soc_dapm_widget *
> snd_soc_dapm_new_control(struct snd_soc_dapm_context *dapm,
> const struct snd_soc_dapm_widget *widget)
> {
<snip>
> case snd_soc_dapm_regulator_supply:
> case snd_soc_dapm_clock_supply:
> w->power_check = dapm_supply_check_power;
> break;
<snip>
> }

Later we call 'dapm_widget_power_check()' which calls into the function
pointer we know to be 'dapm_supply_check_power()'.

> static int dapm_widget_power_check(struct snd_soc_dapm_widget *w)
> {
> if (w->power_checked)
> return w->new_power;
>
> if (w->force)
> w->new_power = 1;
> else
> w->new_power = w->power_check(w);
>
> w->power_checked = true;
>
> return w->new_power;
> }

The problem seems to be that 'dapm_supply_check_power()' then calls back
into 'dapm_widget_power_check()'. Then round and round we go!

> /* Check to see if a power supply is needed */
> static int dapm_supply_check_power(struct snd_soc_dapm_widget *w)
> {
<snip>
> /* Check if one of our outputs is connected */
> list_for_each_entry(path, &w->sinks, list_source) {
> DAPM_UPDATE_STAT(w, neighbour_checks);
>
> if (path->weak)
> continue;
>
> if (path->connected &&
> !path->connected(path->source, path->sink))
> continue;
>
> if (!path->sink)
> continue;
>
> if (dapm_widget_power_check(path->sink)) /* <-- Doh! */
> return 1;
> }
<snip>
> }

Can you shed some light on what the correct solution might be?

Any help would be gratefully received.

Kind regards,
Lee

--
Lee Jones
Linaro ST-Ericsson Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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