[v3,05/20] ASoC: tegra20: spdif: Set FIFO trigger level

Commit Message

Dmitry Osipenko Dec. 2, 2021, 4:23 p.m. UTC

FIFO trigger level must be not less than the size of DMA burst, otherwise
audio will be played x4 faster that it should be because part of the DMA
data will be dropped on FIFO input buffer overflow.

Signed-off-by: Dmitry Osipenko <[e-mail]>
---
 sound/soc/tegra/tegra20_spdif.c | 8 ++++++++
 1 file changed, 8 insertions(+)

Patch

diff --git a/sound/soc/tegra/tegra20_spdif.c b/sound/soc/tegra/tegra20_spdif.c
index 7751575cd6d6..6f0570cde964 100644
--- a/sound/soc/tegra/tegra20_spdif.c
+++ b/sound/soc/tegra/tegra20_spdif.c
@@ -69,6 +69,14 @@  static int tegra20_spdif_hw_params(struct snd_pcm_substream *substream,
 
 	regmap_update_bits(spdif->regmap, TEGRA20_SPDIF_CTRL, mask, val);
 
+	/*
+	 * FIFO trigger level must be bigger than DMA burst or equal to it,
+	 * otherwise data is discarded on overflow.
+	 */
+	regmap_update_bits(spdif->regmap, TEGRA20_SPDIF_DATA_FIFO_CSR,
+			   TEGRA20_SPDIF_DATA_FIFO_CSR_TX_ATN_LVL_MASK,
+			   TEGRA20_SPDIF_DATA_FIFO_CSR_TX_ATN_LVL_TU4_WORD_FULL);
+
 	switch (params_rate(params)) {
 	case 32000:
 		spdifclock = 4096000;