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

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Message-ID: <4e4ef149-66b1-ce44-76a1-0221a8a7f5a7@nvidia.com>
Date:   Fri, 25 Jan 2019 12:38:36 +0530
From:   Sameer Pujar <spujar@...dia.com>
To:     Takashi Iwai <tiwai@...e.de>
CC:     <pierre-louis.bossart@...ux.intel.com>, <perex@...ex.cz>,
        <alsa-devel@...a-project.org>, <thierry.reding@...il.com>,
        <jonathanh@...dia.com>, <rlokhande@...dia.com>,
        <linux-kernel@...r.kernel.org>, <linux-tegra@...r.kernel.org>
Subject: Re: [PATCH] ALSA: hda/tegra: enable clock during probe


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@...dia.com>
>> Reviewed-by: Ravindra Lokhande <rlokhande@...dia.com>
>> Reviewed-by: Jon Hunter <jonathanh@...dia.com>
> (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