Re: [PATCH] ALSA: hda/tegra: enable clock during probe

[Sameer Pujar]

On 1/25/2019 12:38 AM, Takashi Iwai wrote:
> On Thu, 24 Jan 2019 18:36:43 +0100,
> Sameer Pujar wrote:
> > If CONFIG_PM is disabled or runtime PM calls are forbidden, the clocks
> > will not be ON. This could cause issue during probe, where hda init
> > setup is done. This patch checks whether runtime PM is enabled or not.
> > If disabled, clocks are enabled in probe() and disabled in remove()
> >
> > This patch does following minor changes as cleanup,
> >    * return code check for pm_runtime_get_sync() to take care of failure
> >      and exit gracefully.
> >    * In remove path runtime PM is disabled before calling snd_card_free().
> >    * hda_tegra_disable_clocks() is moved out of CONFIG_PM_SLEEP check.
> >    * runtime PM callbacks moved out of CONFIG_PM check
> >
> > Signed-off-by: Sameer Pujar <spujar@xxxxxxxxxx>
> > Reviewed-by: Ravindra Lokhande <rlokhande@xxxxxxxxxx>
> > Reviewed-by: Jon Hunter <jonathanh@xxxxxxxxxx>
> (snip)
> > @@ -555,6 +553,13 @@ static int hda_tegra_probe(struct platform_device *pdev)
> >   	if (!azx_has_pm_runtime(chip))
> >   		pm_runtime_forbid(hda->dev);
> >   
> > +	/* explicit resume if runtime PM is disabled */
> > +	if (!pm_runtime_enabled(hda->dev)) {
> > +		err = hda_tegra_runtime_resume(hda->dev);
> > +		if (err)
> > +			goto out_free;
> > +	}
> > +
> >   	schedule_work(&hda->probe_work);
> Calling runtime_resume here is really confusing...
>
>
> > @@ -571,7 +576,14 @@ static void hda_tegra_probe_work(struct work_struct *work)
> >   	struct platform_device *pdev = to_platform_device(hda->dev);
> >   	int err;
> >   
> > -	pm_runtime_get_sync(hda->dev);
> > +	err = pm_runtime_get_sync(hda->dev);
> > +	if (err < 0) {
> > +		dev_err(hda->dev,
> > +			"failed in pm_runtime_get_syc with err = %d\n",
> > +			err);
> > +		return;
> > +	}
> This pm_runtime_get_sync() is needed just because you enabled runtime
> PM before probe_work.  Why not deferring the runtime PM enablement
> after probing done?
I think what you are suggesting can be done and simplify things further.
I can get rid of pm_runtime_get_sync/pm_runtime_put in probe work.
> That is what we need is the hda_tegra_enable_clocks() call at probe
> unconditionally before enabling runtime PM.
>
> >   	err = hda_tegra_first_init(chip, pdev);
> >   	if (err < 0)
> >   		goto out_free;
> > @@ -599,12 +611,13 @@ static void hda_tegra_probe_work(struct work_struct *work)
> >   
> >   static int hda_tegra_remove(struct platform_device *pdev)
> >   {
> > -	int ret;
> > -
> > -	ret = snd_card_free(dev_get_drvdata(&pdev->dev));
> >   	pm_runtime_disable(&pdev->dev);
> > +	if (!pm_runtime_status_suspended(&pdev->dev)) {
> > +		hda_tegra_runtime_suspend(&pdev->dev);
> > +		pm_runtime_set_suspended(&pdev->dev);
> > +	}
> > -	return ret;
> > +	return snd_card_free(dev_get_drvdata(&pdev->dev));
>
> Forcing the suspend *before* snd_card_free() doesn't sound right.
> It's the point before the disconnect and release procedure of all the
> rest.  That is, the other hardware components are still active at this
> point.

Ok, I will keep the sequence same and publish updated version.

Thanks,
Sameer.

> thanks,
>
> Takashi