[alsa-devel] [RFC PATCH 17/40] soundwire: bus: use runtime_pm_get_sync/pm when enabled

[Andy Shevchenko]

On Fri, Jul 26, 2019 at 01:08:57PM -0500, Pierre-Louis Bossart wrote:
> This thread became unreadable with interleaved top-posting, allow me restate
> the options and ask PM folks what they think
> 
> On 7/25/19 6:40 PM, Pierre-Louis Bossart wrote:
> > Not all platforms support runtime_pm for now, let's use runtime_pm
> > only when enabled.

Just a side note below...

> > -	ret = pm_runtime_get_sync(slave->bus->dev);
> > -	if (ret < 0)

Here...

> > -		return ret;
> > +	if (pm_runtime_enabled(slave->bus->dev)) {
> > +		ret = pm_runtime_get_sync(slave->bus->dev);
> > +		if (ret < 0)

...and thus here...

> > +			return ret;
> > +	}
> >   	ret = sdw_transfer(slave->bus, &msg);
> > -	pm_runtime_put(slave->bus->dev);
> > +
> > +	if (pm_runtime_enabled(slave->bus->dev))
> > +		pm_runtime_put(slave->bus->dev);
> 
> This is option1: we explicitly test if pm_runtime is enabled before calling
> _get_sync() and _put()
> 
> option2 (suggested by Jan Kotas): catch the -EACCESS error code
> 
>  	ret = pm_runtime_get_sync(slave->bus->dev);
> -	if (ret < 0)
> +	if (ret < 0 && ret != -EACCES)

...and here, the pm_runtime_put_noidle() call is missed.

>  		return ret;
> 
> option3: ignore the return value as done in quite a few drivers
> 
> Are there any other options? I am personally surprised this is not handled
> in the pm_runtime core, not sure why users need to test for this?

-- 
With Best Regards,
Andy Shevchenko