ASoC: fsl_sai: Enable combine mode soft

The fsl_sai driver calculates the number of pins used and enables
multiple channels if necessary. This means the SAI expects data in
one FIFO per pin. The SDMA engine only services a single FIFO, so
multi pin support doesn't work at all.

This patch enables the software combine mode in chips that support
it. With this the SAI presents only a single FIFO to the outside
and distributes the data into the different FIFOs internally.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20220111081518.982437-1-s.hauer@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/fsl/fsl_sai.c

@@ -517,6 +517,10 @@ static int fsl_sai_hw_params(struct snd_pcm_substream *substream,
 				   FSL_SAI_CR5_FBT_MASK, val_cr5);
 	}
 
+	if (sai->soc_data->pins > 1)
+		regmap_update_bits(sai->regmap, FSL_SAI_xCR4(tx, ofs),
+				   FSL_SAI_CR4_FCOMB_MASK, FSL_SAI_CR4_FCOMB_SOFT);
+
 	regmap_update_bits(sai->regmap, FSL_SAI_xCR3(tx, ofs),
 			   FSL_SAI_CR3_TRCE_MASK,
 			   FSL_SAI_CR3_TRCE((1 << pins) - 1));
@@ -1195,6 +1199,7 @@ static const struct fsl_sai_soc_data fsl_sai_vf610_data = {
 	.use_imx_pcm = false,
 	.use_edma = false,
 	.fifo_depth = 32,
+	.pins = 1,
 	.reg_offset = 0,
 	.mclk0_is_mclk1 = false,
 	.flags = 0,
@@ -1204,6 +1209,7 @@ static const struct fsl_sai_soc_data fsl_sai_imx6sx_data = {
 	.use_imx_pcm = true,
 	.use_edma = false,
 	.fifo_depth = 32,
+	.pins = 1,
 	.reg_offset = 0,
 	.mclk0_is_mclk1 = true,
 	.flags = 0,
@@ -1213,6 +1219,7 @@ static const struct fsl_sai_soc_data fsl_sai_imx7ulp_data = {
 	.use_imx_pcm = true,
 	.use_edma = false,
 	.fifo_depth = 16,
+	.pins = 2,
 	.reg_offset = 8,
 	.mclk0_is_mclk1 = false,
 	.flags = PMQOS_CPU_LATENCY,
@@ -1222,6 +1229,7 @@ static const struct fsl_sai_soc_data fsl_sai_imx8mq_data = {
 	.use_imx_pcm = true,
 	.use_edma = false,
 	.fifo_depth = 128,
+	.pins = 8,
 	.reg_offset = 8,
 	.mclk0_is_mclk1 = false,
 	.flags = 0,
@@ -1231,6 +1239,7 @@ static const struct fsl_sai_soc_data fsl_sai_imx8qm_data = {
 	.use_imx_pcm = true,
 	.use_edma = true,
 	.fifo_depth = 64,
+	.pins = 1,
 	.reg_offset = 0,
 	.mclk0_is_mclk1 = false,
 	.flags = 0,

sound/soc/fsl/fsl_sai.h

@@ -223,6 +223,7 @@ struct fsl_sai_soc_data {
 	bool use_edma;
 	bool mclk0_is_mclk1;
 	unsigned int fifo_depth;
+	unsigned int pins;
 	unsigned int reg_offset;
 	unsigned int flags;
 };