[PATCH 1/2] ASoC: SOF: pcm: use pm_resume_and_get() on component probe

[Pierre-Louis Bossart]

Before initiating IPC and/or bus transactions when loading the
topology during a component probe, which happens on card
registration/creation, make sure the device for the SOF driver is
pm_runtime active.

The SOF probe is not necessarily followed by the component probe, such
a timing assumption can be broken in driver bind/unbind tests. This
can be artifially shown if the module for the machine driver is
'blacklisted' and the SOF device becomes pm_runtime_suspended before
manually calling modprobe to register the card.

In an initial experiment, pm_resume_and_get() was called from
soc-component.c, since the current ASoC component model is arguably
missing dependencies between component status and device
status. However this approach proved too invasive and breaks all
existing HDMI playback solutions on Intel platforms.

While this will result in duplication of code, generating pm_runtime
transitions only if strictly required for a given component makes more
sense overall. This patch adds the pm_runtime resume transition for
SOF only.

BugLink: https://github.com/thesofproject/linux/issues/3651
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
Reviewed-by: Rander Wang <rander.wang at intel.com>
Reviewed-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao at linux.intel.com>
Reviewed-by: Péter Ujfalusi <peter.ujfalusi at linux.intel.com>
---
 sound/soc/sof/pcm.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/sound/soc/sof/pcm.c b/sound/soc/sof/pcm.c
index a76d0b5b2ad95..27504abc5385f 100644
--- a/sound/soc/sof/pcm.c
+++ b/sound/soc/sof/pcm.c
@@ -604,6 +604,14 @@ static int sof_pcm_probe(struct snd_soc_component *component)
 	const char *tplg_filename;
 	int ret;
 
+	/*
+	 * make sure the device is pm_runtime_active before loading the
+	 * topology and initiating IPC or bus transactions
+	 */
+	ret = pm_runtime_resume_and_get(component->dev);
+	if (ret < 0 && ret != -EACCES)
+		return ret;
+
 	/* load the default topology */
 	sdev->component = component;
 
@@ -621,6 +629,9 @@ static int sof_pcm_probe(struct snd_soc_component *component)
 		return ret;
 	}
 
+	pm_runtime_mark_last_busy(component->dev);
+	pm_runtime_put_autosuspend(component->dev);
+
 	return ret;
 }
 
-- 
2.34.1