[alsa-devel] [PATCH 4/9] ASoC: SOF: pm: Introduce DSP power states

[Pierre-Louis Bossart]

From: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>

Add a new enum sof_dsp_power_states for all the possible
the DSP device states. The SOF driver currently handles
only the D0 and D3 states and support for other states
will be added later as needed.

Also, add a helper to determine the target DSP power state
based on the system suspend target.
The snd_sof_dsp_d0i3_on_suspend() function is renamed to
snd_sof_stream_suspend_ignored() to be more indicative
of what it does and it used to determine the target
DSP state during system suspend.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan at linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart at linux.intel.com>
---
 sound/soc/sof/pm.c        | 38 +++++++++++++++++++++++++++++++++++++-
 sound/soc/sof/sof-audio.c |  2 +-
 sound/soc/sof/sof-audio.h |  2 +-
 sound/soc/sof/sof-priv.h  | 10 ++++++++++
 4 files changed, 49 insertions(+), 3 deletions(-)

diff --git a/sound/soc/sof/pm.c b/sound/soc/sof/pm.c
index c86ac1e84bd7..bec25cb6beec 100644
--- a/sound/soc/sof/pm.c
+++ b/sound/soc/sof/pm.c
@@ -12,6 +12,42 @@
 #include "sof-priv.h"
 #include "sof-audio.h"
 
+/*
+ * Helper function to determine the target DSP state during
+ * system suspend. This function only cares about the device
+ * D-states. Platform-specific substates, if any, should be
+ * handled by the platform-specific parts.
+ */
+static u32 snd_sof_dsp_power_target(struct snd_sof_dev *sdev)
+{
+	u32 target_dsp_state;
+
+	switch (sdev->system_suspend_target) {
+	case SOF_SUSPEND_S3:
+		/* DSP should be in D3 if the system is suspending to S3 */
+		target_dsp_state = SOF_DSP_PM_D3;
+		break;
+	case SOF_SUSPEND_S0IX:
+		/*
+		 * Currently, the only criterion for retaining the DSP in D0
+		 * is that there are streams that ignored the suspend trigger.
+		 * Additional criteria such Soundwire clock-stop mode and
+		 * device suspend latency considerations will be added later.
+		 */
+		if (snd_sof_stream_suspend_ignored(sdev))
+			target_dsp_state = SOF_DSP_PM_D0;
+		else
+			target_dsp_state = SOF_DSP_PM_D3;
+		break;
+	default:
+		/* This case would be during runtime suspend */
+		target_dsp_state = SOF_DSP_PM_D3;
+		break;
+	}
+
+	return target_dsp_state;
+}
+
 static int sof_send_pm_ctx_ipc(struct snd_sof_dev *sdev, int cmd)
 {
 	struct sof_ipc_pm_ctx pm_ctx;
@@ -169,7 +205,7 @@ static int sof_suspend(struct device *dev, bool runtime_suspend)
 		}
 	}
 
-	if (snd_sof_dsp_d0i3_on_suspend(sdev)) {
+	if (snd_sof_dsp_power_target(sdev) == SOF_DSP_PM_D0) {
 		/* suspend to D0i3 */
 		ret = snd_sof_set_d0_substate(sdev, SOF_DSP_D0I3);
 		if (ret < 0) {
diff --git a/sound/soc/sof/sof-audio.c b/sound/soc/sof/sof-audio.c
index 345e42ee4783..d16571ca129c 100644
--- a/sound/soc/sof/sof-audio.c
+++ b/sound/soc/sof/sof-audio.c
@@ -11,7 +11,7 @@
 #include "sof-audio.h"
 #include "ops.h"
 
-bool snd_sof_dsp_d0i3_on_suspend(struct snd_sof_dev *sdev)
+bool snd_sof_stream_suspend_ignored(struct snd_sof_dev *sdev)
 {
 	struct snd_sof_pcm *spcm;
 
diff --git a/sound/soc/sof/sof-audio.h b/sound/soc/sof/sof-audio.h
index a62fb2da6a6e..a2702afbd9a1 100644
--- a/sound/soc/sof/sof-audio.h
+++ b/sound/soc/sof/sof-audio.h
@@ -202,7 +202,7 @@ int snd_sof_ipc_set_get_comp_data(struct snd_sof_control *scontrol,
 /* PM */
 int sof_restore_pipelines(struct device *dev);
 int sof_set_hw_params_upon_resume(struct device *dev);
-bool snd_sof_dsp_d0i3_on_suspend(struct snd_sof_dev *sdev);
+bool snd_sof_stream_suspend_ignored(struct snd_sof_dev *sdev);
 
 /* Machine driver enumeration */
 int sof_machine_register(struct snd_sof_dev *sdev, void *pdata);
diff --git a/sound/soc/sof/sof-priv.h b/sound/soc/sof/sof-priv.h
index 1839cc51957d..a7c6109acd98 100644
--- a/sound/soc/sof/sof-priv.h
+++ b/sound/soc/sof/sof-priv.h
@@ -54,6 +54,16 @@ extern int sof_core_debug;
 	(IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_ENABLE_DEBUGFS_CACHE) || \
 	 IS_ENABLED(CONFIG_SND_SOC_SOF_DEBUG_IPC_FLOOD_TEST))
 
+/* DSP power state */
+enum sof_dsp_power_states {
+	SOF_DSP_PM_D0,
+	SOF_DSP_PM_D1,
+	SOF_DSP_PM_D2,
+	SOF_DSP_PM_D3_HOT,
+	SOF_DSP_PM_D3,
+	SOF_DSP_PM_D3_COLD,
+};
+
 /* DSP D0ix sub-state */
 enum sof_d0_substate {
 	SOF_DSP_D0I0 = 0,	/* DSP default D0 substate */
-- 
2.20.1