The prepare() ioctl for BE dai link gets called both
when the stream is started and when it is resumed from
suspend. SOF uses this ioctl to set the hw params
again only if the stream has been suspended.

When the stream is started, the hw_params ioctl gets called
before prepare() and hw_params is set for the BE dai link.
So the prepare call does not need to do anything further.

When the stream resumes after system suspend, SOF requires
that the hw_params be set again for the BE dai. In order
to determine which streams should set the hw params
during prepare(), an internal flag called "hw_params_upon_resume"
is introduced in struct sof_intel_hda_stream. The flag is set
for hda streams when the sof device suspends and is
cleared after hw_params is set.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

Add support for saving and restoring DSP context in D3 to host DDR.

The suspend callback includes: suspend all pcm's stream that are running,
send CTX_SAVE ipc, drop all ipc's, release trace dma and then
power off the DSP.

And the resume callback performs the following steps: load FW, run FW,
re-initialize trace, restore pipeline, restore the kcontrol values
and finally send the ctx restore ipc to the dsp.

The streams that are suspended are resumed by the ALSA resume trigger.
If the streams are paused during system suspend, they are marked
explicitly so they can be restored during PAUSE_RELEASE.

Signed-off-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Mark Brown <broonie@kernel.org>