diff mbox series

[v5,04/11] ASoC: tegra20: spdif: Set FIFO trigger level

Message ID 20211217175606.22645-5-digetx@gmail.com
State Handled Elsewhere
Headers show
Series [v5,01/11] ASoC: dt-bindings: Add binding for Tegra20 S/PDIF | expand

Commit Message

Dmitry Osipenko Dec. 17, 2021, 5:55 p.m. UTC 
FIFO trigger level must be bigger than or equal to the size of DMA burst,
otherwise audio will be played x4 faster than it should be because part of
the DMA data will be dropped on FIFO input buffer overflow.

Acked-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Dmitry Osipenko <digetx@gmail.com>
---
 sound/soc/tegra/tegra20_spdif.c | 8 ++++++++
 1 file changed, 8 insertions(+)
diff mbox series

Patch

diff --git a/sound/soc/tegra/tegra20_spdif.c b/sound/soc/tegra/tegra20_spdif.c
index 57a6c576b91f..e45e371edc42 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;