[PATCH 18/18] soundwire: intel: reinitialize IP+DSP in .prepare()

[Pierre-Louis Bossart]

From: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>

The .prepare() callback is invoked for normal streaming, underflows or
during the system resume transition. In the latter case, the context
for the ALH PDIs is lost, and the DSP is not initialized properly
either, but the bus parameters don't need to be recomputed.

To avoid keeping track of state variables, it's simpler to just
reinitialize the SHIM/ALH/Cadence/DSP settings in .prepare.

Signed-off-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
---
 drivers/soundwire/intel.c | 40 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/soundwire/intel.c b/drivers/soundwire/intel.c
index f0f9a6252522..ec6c58635a99 100644
--- a/drivers/soundwire/intel.c
+++ b/drivers/soundwire/intel.c
@@ -117,6 +117,8 @@ struct sdw_intel {
 	struct sdw_cdns cdns;
 	int instance;
 	struct sdw_intel_link_res *link_res;
+	struct snd_pcm_hw_params *hw_params;
+	struct sdw_cdns_pdi *pdi;
 #ifdef CONFIG_DEBUG_FS
 	struct dentry *debugfs;
 #endif
@@ -813,6 +815,8 @@ static int intel_hw_params(struct snd_pcm_substream *substream,
 	intel_pdi_alh_configure(sdw, pdi);
 	sdw_cdns_config_stream(cdns, ch, dir, pdi);
 
+	sdw->pdi = pdi;
+	sdw->hw_params = params;
 
 	/* Inform DSP about PDI stream number */
 	ret = intel_params_stream(sdw, substream, dai, params,
@@ -856,7 +860,11 @@ static int intel_hw_params(struct snd_pcm_substream *substream,
 static int intel_prepare(struct snd_pcm_substream *substream,
 			 struct snd_soc_dai *dai)
 {
+	struct sdw_cdns *cdns = snd_soc_dai_get_drvdata(dai);
+	struct sdw_intel *sdw = cdns_to_intel(cdns);
 	struct sdw_cdns_dma_data *dma;
+	int ch, dir;
+	int ret;
 
 	dma = snd_soc_dai_get_dma_data(dai, substream);
 	if (!dma) {
@@ -865,7 +873,35 @@ static int intel_prepare(struct snd_pcm_substream *substream,
 		return -EIO;
 	}
 
-	return sdw_prepare_stream(dma->stream);
+	/*
+	 * .prepare() is called after system resume, where we need to
+	 * reinitialize the SHIM/ALH/Cadence IP. To avoid dealing with
+	 * complicated state machines, we just re-initialize in all
+	 * cases since there are no side effects.
+	 */
+
+	/* configure stream */
+	ch = params_channels(sdw->hw_params);
+	if (substream->stream == SNDRV_PCM_STREAM_CAPTURE)
+		dir = SDW_DATA_DIR_RX;
+	else
+		dir = SDW_DATA_DIR_TX;
+
+	intel_pdi_shim_configure(sdw, sdw->pdi);
+	intel_pdi_alh_configure(sdw, sdw->pdi);
+	sdw_cdns_config_stream(cdns, ch, dir, sdw->pdi);
+
+	/* Inform DSP about PDI stream number */
+	ret = intel_params_stream(sdw, substream, dai, sdw->hw_params,
+				  sdw->instance,
+				  sdw->pdi->intel_alh_id);
+	if (ret)
+		goto err;
+
+	ret = sdw_prepare_stream(dma->stream);
+
+err:
+	return ret;
 }
 
 static int intel_trigger(struct snd_pcm_substream *substream, int cmd,
@@ -936,6 +972,8 @@ intel_hw_free(struct snd_pcm_substream *substream, struct snd_soc_dai *dai)
 		return ret;
 	}
 
+	sdw->hw_params = NULL;
+	sdw->pdi = NULL;
 	sdw_release_stream(dma->stream);
 
 	return 0;
-- 
2.20.1