[Sound-open-firmware] About sof and D0 D3 states, 'standby' and 'suspend to RAM'

[josep lladonosa capell]

Hello,

I have found[1]  that sof driver works (for now?) only two power
states: D0 (DSP ON) and D3 (DSP OFF).
In a laptop with battery, not connected to AC, I have many
"D0->D3->D0" state changes during system operation [3].When entering
into to D0, all firmware is loaded again, DSP set up and so (obvious,
as DSPs where off).

My guess is that this transition happens in a power state transition
lower than Suspend to RAM, i.e., Suspend-to-idle or Standby. [2]

Should not be the transition to D3 state done in a kernel transition
to S3 or higher only (Suspend to RAM, hibernate)?

I have digged into the code and found the debug line in
sound/soc/sof/intel/hda-codec.c:
dev_dbg(bus->dev, "Turning i915 HDAC power %d\n", enable);
and function hda_suspend is in hda-dsp.c:
static int hda_suspend(struct snd_sof_dev *sdev, bool runtime_suspend)

Regards,
Josep


[1]: https://thesofproject.github.io/latest/developer_guides/linux_driver/architecture/sof_driver_arch.html#power-management
[2]: https://www.kernel.org/doc/html/v5.6/admin-guide/pm/sleep-states.html#suspend-to-idle
[3]: Log from a session in a laptop working on its battery (only D0 D3
transition debug  lines):
++++++++++++++++++++++++++++
Apr 23 08:06:20 debian kernel: [ 1357.524900] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:06:23 debian kernel: [ 1359.967511] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:06:29 debian kernel: [ 1366.697617] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:06:32 debian kernel: [ 1368.976763] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:07:41 debian kernel: [ 1438.758013] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:07:44 debian kernel: [ 1440.968094] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:08:29 debian kernel: [ 1486.346591] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:08:32 debian kernel: [ 1488.968805] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:08:33 debian kernel: [ 1489.970170] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:08:35 debian kernel: [ 1492.134071] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:09:43 debian kernel: [ 1560.535211] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:09:46 debian kernel: [ 1563.180713] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:11:12 debian kernel: [ 1649.719864] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:11:15 debian kernel: [ 1652.347401] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:11:23 debian kernel: [ 1660.328147] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:11:26 debian kernel: [ 1662.895611] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:11:38 debian kernel: [ 1675.404116] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:11:41 debian kernel: [ 1678.023978] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:11:43 debian kernel: [ 1680.128389] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:11:45 debian kernel: [ 1682.563802] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:11:46 debian kernel: [ 1683.187391] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:11:48 debian kernel: [ 1685.358684] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:11:52 debian kernel: [ 1689.704048] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:11:55 debian kernel: [ 1692.350057] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:11:56 debian kernel: [ 1693.056443] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:11:58 debian kernel: [ 1695.315083] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:12:28 debian kernel: [ 1725.232502] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:12:30 debian kernel: [ 1727.379811] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:12:35 debian kernel: [ 1732.240686] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:12:38 debian kernel: [ 1734.816780] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:12:39 debian kernel: [ 1736.719892] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:12:42 debian kernel: [ 1739.340736] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:12:51 debian kernel: [ 1748.048546] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
Apr 23 08:12:53 debian kernel: [ 1750.688659] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 0
Apr 23 08:12:58 debian kernel: [ 1755.075835] sof-audio-pci
0000:00:1f.3: Turning i915 HDAC power 1
+++++++++++++++++++++++++++++++++++++++++++++++++++++++