[PATCH] ASoC: rsnd: dma: set bus width to data width for monaural data

From: Jiada Wang
Date: Tue Oct 22 2019 - 14:55:18 EST


According to R-Car3 HW manual 40.3.3 (Data Format on Audio Local Bus),
in case of monaural data writing or reading through Audio-DMAC,
it's always in Left Justified format, so both src and dst
DMA Bus width should be equal to physical data width.

Therefore set src and dst's DMA bus width to:
- [monaural case] data width
- [non-monaural case] 32bits (as prior applying the patch)

Cc: Andrew Gabbasov <andrew_gabbasov@xxxxxxxxxx>
Cc: Timo Wischer <twischer@xxxxxxxxxxxxxx>
Signed-off-by: Jiada Wang <jiada_wang@xxxxxxxxxx>
Signed-off-by: Eugeniu Rosca <erosca@xxxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20191022185518.12838-1-erosca@xxxxxxxxxxxxxx
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
---
sound/soc/sh/rcar/dma.c | 30 ++++++++++++++++++++++++++++--
1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/sound/soc/sh/rcar/dma.c b/sound/soc/sh/rcar/dma.c
index 0324a5c39619..bcb6d5960661 100644
--- a/sound/soc/sh/rcar/dma.c
+++ b/sound/soc/sh/rcar/dma.c
@@ -165,14 +165,40 @@ static int rsnd_dmaen_start(struct rsnd_mod *mod,
struct device *dev = rsnd_priv_to_dev(priv);
struct dma_async_tx_descriptor *desc;
struct dma_slave_config cfg = {};
+ enum dma_slave_buswidth buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;
int is_play = rsnd_io_is_play(io);
int ret;

+ /*
+ * in case of monaural data writing or reading through Audio-DMAC
+ * data is always in Left Justified format, so both src and dst
+ * DMA Bus width need to be set equal to physical data width.
+ */
+ if (rsnd_runtime_channel_original(io) == 1) {
+ struct snd_pcm_runtime *runtime = rsnd_io_to_runtime(io);
+ int bits = snd_pcm_format_physical_width(runtime->format);
+
+ switch (bits) {
+ case 8:
+ buswidth = DMA_SLAVE_BUSWIDTH_1_BYTE;
+ break;
+ case 16:
+ buswidth = DMA_SLAVE_BUSWIDTH_2_BYTES;
+ break;
+ case 32:
+ buswidth = DMA_SLAVE_BUSWIDTH_4_BYTES;
+ break;
+ default:
+ dev_err(dev, "invalid format width %d\n", bits);
+ return -EINVAL;
+ }
+ }
+
cfg.direction = is_play ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM;
cfg.src_addr = dma->src_addr;
cfg.dst_addr = dma->dst_addr;
- cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
- cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
+ cfg.src_addr_width = buswidth;
+ cfg.dst_addr_width = buswidth;

dev_dbg(dev, "%s %pad -> %pad\n",
rsnd_mod_name(mod),
--
2.20.1