[PATCH] ASoC: fsl_spdif: implement bypass mode from in to out

From: Shengjiu Wang
Date: Sun Sep 26 2021 - 06:14:07 EST


From: Viorel Suman <viorel.suman@xxxxxxx>

Implement SPDIF bypass mode. It implies internal SoC
routing of SPDIF input signal to SPDIF output signal. The
test bed requires two boards: B1 configured in bypass mode,
and B2 to feed B1 SPDIF RX port and read B1 SPDIF TX port:
B2 TX -> B1 RX,
B2 RX <- B1 TX.
The test procedure:
a) Boot both boards
b) B2: start "arecord <spdifcard> -r 48kHz | aplay <local DAC>"
c) B2: start "aplay <spdifcard> -r 48kHz <2ch 48kHz audio file>"
d) B1: enable bypass mode:
amixer -cimxspdif cset numid=8,iface=PCM,name='Bypass Mode' on
e) B2: check DAC audio, make sure the same sample rate is used at
steps b) and c), in example above the rate is 48kHz.
f) B1: try to run "aplay" or "arecord" on imxspdif card while in
bypass mode - both must fail until bypass mode is disabled
g) B1: disable bypass mode:
amixer -cimxspdif cset numid=8,iface=PCM,name='Bypass Mode' off
h) B1: check the usual playback and capture on imxspdif card.
During this test try to set bypass mode - must not be allowed
while playback or capture is running.

Signed-off-by: Viorel Suman <viorel.suman@xxxxxxx>
Signed-off-by: Shengjiu Wang <shengjiu.wang@xxxxxxx>
---
sound/soc/fsl/fsl_spdif.c | 74 +++++++++++++++++++++++++++++++++++++++
1 file changed, 74 insertions(+)

diff --git a/sound/soc/fsl/fsl_spdif.c b/sound/soc/fsl/fsl_spdif.c
index 928b59069283..d178b479c8bd 100644
--- a/sound/soc/fsl/fsl_spdif.c
+++ b/sound/soc/fsl/fsl_spdif.c
@@ -111,6 +111,7 @@ struct spdif_mixer_control {
* @dma_params_tx: DMA parameters for transmit channel
* @dma_params_rx: DMA parameters for receive channel
* @regcache_srpc: regcache for SRPC
+ * @bypass: status of bypass input to output
*/
struct fsl_spdif_priv {
const struct fsl_spdif_soc_data *soc;
@@ -133,6 +134,7 @@ struct fsl_spdif_priv {
struct snd_dmaengine_dai_dma_data dma_params_rx;
/* regcache for SRPC */
u32 regcache_srpc;
+ bool bypass;
};

static struct fsl_spdif_soc_data fsl_spdif_vf610 = {
@@ -905,6 +907,69 @@ static int fsl_spdif_rx_rcm_put(struct snd_kcontrol *kcontrol,
return 0;
}

+static int fsl_spdif_bypass_get(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct snd_soc_dai *dai = snd_kcontrol_chip(kcontrol);
+ struct fsl_spdif_priv *priv = snd_soc_dai_get_drvdata(dai);
+
+ ucontrol->value.integer.value[0] = priv->bypass ? 1 : 0;
+
+ return 0;
+}
+
+static int fsl_spdif_bypass_put(struct snd_kcontrol *kcontrol,
+ struct snd_ctl_elem_value *ucontrol)
+{
+ struct snd_soc_dai *dai = snd_kcontrol_chip(kcontrol);
+ struct fsl_spdif_priv *priv = snd_soc_dai_get_drvdata(dai);
+ struct snd_soc_card *card = dai->component->card;
+ bool set = (ucontrol->value.integer.value[0] != 0);
+ struct regmap *regmap = priv->regmap;
+ struct snd_soc_pcm_runtime *rtd;
+ u32 scr, mask;
+ int stream;
+
+ rtd = snd_soc_get_pcm_runtime(card, card->dai_link);
+
+ if (priv->bypass == set)
+ return 0; /* nothing to do */
+
+ if (snd_soc_dai_active(dai)) {
+ dev_err(dai->dev, "Cannot change BYPASS mode while stream is running.\n");
+ return -EBUSY;
+ }
+
+ pm_runtime_get_sync(dai->dev);
+
+ if (set) {
+ /* Disable interrupts */
+ regmap_update_bits(regmap, REG_SPDIF_SIE, 0xffffff, 0);
+
+ /* Configure BYPASS mode */
+ scr = SCR_TXSEL_RX | SCR_RXFIFO_OFF;
+ mask = SCR_RXFIFO_FSEL_MASK | SCR_RXFIFO_AUTOSYNC_MASK |
+ SCR_RXFIFO_CTL_MASK | SCR_RXFIFO_OFF_MASK | SCR_TXSEL_MASK;
+ /* Power up SPDIF module */
+ mask |= SCR_LOW_POWER;
+ } else {
+ /* Power down SPDIF module, disable TX */
+ scr = SCR_LOW_POWER | SCR_TXSEL_OFF;
+ mask = SCR_LOW_POWER | SCR_TXSEL_MASK;
+ }
+
+ regmap_update_bits(regmap, REG_SPDIF_SCR, mask, scr);
+
+ /* Disable playback & capture if BYPASS mode is enabled, enable otherwise */
+ for_each_pcm_streams(stream)
+ rtd->pcm->streams[stream].substream_count = (set ? 0 : 1);
+
+ priv->bypass = set;
+ pm_runtime_put_sync(dai->dev);
+
+ return 0;
+}
+
/* DPLL lock information */
static int fsl_spdif_rxrate_info(struct snd_kcontrol *kcontrol,
struct snd_ctl_elem_info *uinfo)
@@ -1075,6 +1140,15 @@ static struct snd_kcontrol_new fsl_spdif_ctrls[] = {
.info = fsl_spdif_rxrate_info,
.get = fsl_spdif_rxrate_get,
},
+ /* RX bypass controller */
+ {
+ .iface = SNDRV_CTL_ELEM_IFACE_PCM,
+ .name = "Bypass Mode",
+ .access = SNDRV_CTL_ELEM_ACCESS_READWRITE,
+ .info = snd_ctl_boolean_mono_info,
+ .get = fsl_spdif_bypass_get,
+ .put = fsl_spdif_bypass_put,
+ },
/* User bit sync mode set/get controller */
{
.iface = SNDRV_CTL_ELEM_IFACE_PCM,
--
2.17.1