From 0c93c291321f2ba8dc4cd3d4df74801caaa297db Mon Sep 17 00:00:00 2001
From: Olivier Moysan <olivier.moysan@st.com>
Date: Fri, 11 Oct 2019 10:48:16 +0200
Subject: [PATCH] ASoC: stm32: spdifrx: retry synchronization in sync state
Git-commit: 0c93c291321f2ba8dc4cd3d4df74801caaa297db
Patch-mainline: v5.5-rc1
References: jsc#SLE-16518

When STM32 SPDIFRX is in sync state, allow multiple
synchro attempts, instead of exiting on first unsuccessful
trial. This is useful when spdif signal is not immediately
available on input. This also allows Pulseaudio to check
iec capture device availability when no signal is present.

Signed-off-by: Olivier Moysan <olivier.moysan@st.com>
Link: https://lore.kernel.org/r/20191011084816.14279-1-olivier.moysan@st.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 sound/soc/stm/stm32_spdifrx.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/sound/soc/stm/stm32_spdifrx.c b/sound/soc/stm/stm32_spdifrx.c
index cd4b235fce57..3fd28ee01675 100644
--- a/sound/soc/stm/stm32_spdifrx.c
+++ b/sound/soc/stm/stm32_spdifrx.c
@@ -351,6 +351,8 @@ static int stm32_spdifrx_start_sync(struct stm32_spdifrx_data *spdifrx)
 		     SPDIFRX_CR_CUMSK | SPDIFRX_CR_PTMSK | SPDIFRX_CR_RXSTEO;
 		cr_mask = cr;
 
+		cr |= SPDIFRX_CR_NBTRSET(SPDIFRX_NBTR_63);
+		cr_mask |= SPDIFRX_CR_NBTR_MASK;
 		cr |= SPDIFRX_CR_SPDIFENSET(SPDIFRX_SPDIFEN_SYNC);
 		cr_mask |= SPDIFRX_CR_SPDIFEN_MASK;
 		ret = regmap_update_bits(spdifrx->regmap, STM32_SPDIFRX_CR,
@@ -666,7 +668,7 @@ static irqreturn_t stm32_spdifrx_isr(int irq, void *devid)
 	struct snd_pcm_substream *substream = spdifrx->substream;
 	struct platform_device *pdev = spdifrx->pdev;
 	unsigned int cr, mask, sr, imr;
-	unsigned int flags;
+	unsigned int flags, sync_state;
 	int err = 0, err_xrun = 0;
 
 	regmap_read(spdifrx->regmap, STM32_SPDIFRX_SR, &sr);
@@ -726,11 +728,23 @@ static irqreturn_t stm32_spdifrx_isr(int irq, void *devid)
 	}
 
 	if (err) {
-		/* SPDIFRX in STATE_STOP. Disable SPDIFRX to clear errors */
+		regmap_read(spdifrx->regmap, STM32_SPDIFRX_CR, &cr);
+		sync_state = FIELD_GET(SPDIFRX_CR_SPDIFEN_MASK, cr) &&
+			     SPDIFRX_SPDIFEN_SYNC;
+
+		/* SPDIFRX is in STATE_STOP. Disable SPDIFRX to clear errors */
 		cr = SPDIFRX_CR_SPDIFENSET(SPDIFRX_SPDIFEN_DISABLE);
 		regmap_update_bits(spdifrx->regmap, STM32_SPDIFRX_CR,
 				   SPDIFRX_CR_SPDIFEN_MASK, cr);
 
+		/* If SPDIFRX was in STATE_SYNC, retry synchro */
+		if (sync_state) {
+			cr = SPDIFRX_CR_SPDIFENSET(SPDIFRX_SPDIFEN_SYNC);
+			regmap_update_bits(spdifrx->regmap, STM32_SPDIFRX_CR,
+					   SPDIFRX_CR_SPDIFEN_MASK, cr);
+			return IRQ_HANDLED;
+		}
+
 		if (substream)
 			snd_pcm_stop(substream, SNDRV_PCM_STATE_DISCONNECTED);
 
-- 
2.16.4