ASoC: SOF: Intel: hda: fix null deref on system suspend entry

When system enters suspend with an active stream, SOF core
calls hw_params_upon_resume(). On Intel platforms with HDA DMA used
to manage the link DMA, this leads to call chain of

   hda_dsp_set_hw_params_upon_resume()
 -> hda_dsp_dais_suspend()
 -> hda_dai_suspend()
 -> hda_ipc4_post_trigger()

A bug is hit in hda_dai_suspend() as hda_link_dma_cleanup() is run first,
which clears hext_stream->link_substream, and then hda_ipc4_post_trigger()
is called with a NULL snd_pcm_substream pointer.

Fixes: 2b009fa ("ASoC: SOF: Intel: hda: Unify DAI drv ops for IPC3 and IPC4")
Link: thesofproject/linux#5080
Reviewed-by: Bard Liao <[email protected]>
Signed-off-by: Kai Vehmanen <[email protected]>
Signed-off-by: Pierre-Louis Bossart <[email protected]>
Link: https://patch.msgid.link/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: kv2019i

sound/soc/sof/intel/hda-dai.c

@@ -617,12 +617,6 @@ static int hda_dai_suspend(struct hdac_bus *bus)
 			sdai = swidget->private;
 			ops = sdai->platform_private;
 
-			ret = hda_link_dma_cleanup(hext_stream->link_substream,
-						   hext_stream,
-						   cpu_dai);
-			if (ret < 0)
-				return ret;
-
 			/* for consistency with TRIGGER_SUSPEND  */
 			if (ops->post_trigger) {
 				ret = ops->post_trigger(sdev, cpu_dai,
@@ -631,6 +625,12 @@ static int hda_dai_suspend(struct hdac_bus *bus)
 				if (ret < 0)
 					return ret;
 			}
+
+			ret = hda_link_dma_cleanup(hext_stream->link_substream,
+						   hext_stream,
+						   cpu_dai);
+			if (ret < 0)
+				return ret;
 		}
 	}