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

From: Sameer Pujar
Date: Fri Jan 25 2019 - 02:08:52 EST

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>
@@ -555,6 +553,13 @@ static int hda_tegra_probe(struct platform_device *pdev)
if (!azx_has_pm_runtime(chip))
+ /* 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;
+ }
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));
+ 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

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