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Date:   Wed, 30 Jan 2019 17:40:42 +0100
Message-ID: <s5ha7jicd4l.wl-tiwai@suse.de>
From:   Takashi Iwai <tiwai@suse.de>
To:     "Jon Hunter" <jonathanh@nvidia.com>
Cc:     <pierre-louis.bossart@linux.intel.com>,
        "Sameer Pujar" <spujar@nvidia.com>, <perex@perex.cz>,
        <alsa-devel@alsa-project.org>, <thierry.reding@gmail.com>,
        <mkumard@nvidia.com>, <rlokhande@nvidia.com>, <sharadg@nvidia.com>,
        <linux-kernel@vger.kernel.org>, <linux-tegra@vger.kernel.org>
Subject: Re: [PATCH v2] ALSA: hda/tegra: enable clock during probe
In-Reply-To: <b631310f-93fa-ef4b-7014-d97fcfb2dcdf@nvidia.com>
References: <1548414418-5785-1-git-send-email-spujar@nvidia.com>
        <b631310f-93fa-ef4b-7014-d97fcfb2dcdf@nvidia.com>
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On Wed, 30 Jan 2019 13:45:49 +0100,
Jon Hunter wrote:
> 
> 
> On 25/01/2019 11:06, 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 enables clocks unconditionally during probe.
> > 
> > Along with above, follwoing changes are done.
> >   * enable runtime PM before exiting from probe work. This helps to avoid
> >     usage of pm_runtime_get_sync/pm_runtime_put() in probe work.
> >   * 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@nvidia.com>
> > Reviewed-by: Ravindra Lokhande <rlokhande@nvidia.com>
> > Reviewed-by: Jon Hunter <jonathanh@nvidia.com>
> > ---
> >  sound/pci/hda/hda_tegra.c | 26 +++++++++++++++++---------
> >  1 file changed, 17 insertions(+), 9 deletions(-)
> > 
> > diff --git a/sound/pci/hda/hda_tegra.c b/sound/pci/hda/hda_tegra.c
> > index c8d18dc..ba6175f 100644
> > --- a/sound/pci/hda/hda_tegra.c
> > +++ b/sound/pci/hda/hda_tegra.c
> > @@ -219,7 +219,6 @@ static int hda_tegra_enable_clocks(struct hda_tegra *data)
> >  	return rc;
> >  }
> >  
> > -#ifdef CONFIG_PM_SLEEP
> >  static void hda_tegra_disable_clocks(struct hda_tegra *data)
> >  {
> >  	clk_disable_unprepare(data->hda2hdmi_clk);
> > @@ -227,6 +226,7 @@ static void hda_tegra_disable_clocks(struct hda_tegra *data)
> >  	clk_disable_unprepare(data->hda_clk);
> >  }
> >  
> > +#ifdef CONFIG_PM_SLEEP
> >  /*
> >   * power management
> >   */
> > @@ -257,7 +257,6 @@ static int hda_tegra_resume(struct device *dev)
> >  }
> >  #endif /* CONFIG_PM_SLEEP */
> >  
> > -#ifdef CONFIG_PM
> >  static int hda_tegra_runtime_suspend(struct device *dev)
> >  {
> >  	struct snd_card *card = dev_get_drvdata(dev);
> > @@ -283,7 +282,7 @@ static int hda_tegra_runtime_resume(struct device *dev)
> >  	int rc;
> >  
> >  	rc = hda_tegra_enable_clocks(hda);
> > -	if (rc != 0)
> > +	if (rc)
> >  		return rc;
> >  	if (chip && chip->running) {
> >  		hda_tegra_init(hda);
> > @@ -292,7 +291,6 @@ static int hda_tegra_runtime_resume(struct device *dev)
> >  
> >  	return 0;
> >  }
> > -#endif /* CONFIG_PM */
> >  
> >  static const struct dev_pm_ops hda_tegra_pm = {
> >  	SET_SYSTEM_SLEEP_PM_OPS(hda_tegra_suspend, hda_tegra_resume)
> > @@ -551,9 +549,9 @@ static int hda_tegra_probe(struct platform_device *pdev)
> >  
> >  	dev_set_drvdata(&pdev->dev, card);
> >  
> > -	pm_runtime_enable(hda->dev);
> > -	if (!azx_has_pm_runtime(chip))
> > -		pm_runtime_forbid(hda->dev);
> > +	err = hda_tegra_enable_clocks(hda);
> > +	if (err)
> > +		goto out_free;
> 
> We also need to think about power-domains here. Enabling the clocks
> might not be enough as the appropriate power-domain needs to be enabled.
> For 64-bit Tegra runtime-pm will handle the power-domains (assuming they
> are populated in device-tree). So I still think it is better we call
> pm_runtime_get_sync() at some point rather than just replying on
> enabling the clocks.

If I understand correctly the code, the pm domain is already activated
at calling driver's probe callback.


thanks,

Takashi