Re: [PATCH v2] ALSA: hda/tegra: enable clock during probe

Sameer Pujar
2019-01-31T09:36:43Z

On 1/30/2019 10:10 PM, Takashi Iwai wrote:
> 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.

If there are no further concerns, can we consider this for approval?

Thanks,
Sameer.

>
> thanks,
>
> Takashi