ASoC: tegra20: spdif: Set FIFO trigger level

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 <digetx@gmail.com>
Acked-by: Thierry Reding <treding@nvidia.com>
Link: https://lore.kernel.org/r/20211204143725.31646-6-digetx@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

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;