ASoC: amd: ps: add comments for DMA register mapping

Add comments for DMA register mapping for both the SoundWire manager
instances.

Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda@amd.com>
Link: https://lore.kernel.org/r/20230626105356.2580125-4-Vijendar.Mukunda@amd.com
Signed-off-by: Mark Brown <broonie@kernel.org>

sound/soc/amd/ps/ps-sdw-dma.c

@@ -39,6 +39,11 @@ static struct sdw_dma_ring_buf_reg sdw0_dma_ring_buf_reg[ACP63_SDW0_DMA_MAX_STRE
 	 ACP_AUDIO2_RX_LINEARPOSITIONCNTR_LOW, ACP_AUDIO2_RX_LINEARPOSITIONCNTR_HIGH}
 };
 
+/*
+ * SDW1 instance supports one TX stream and one RX stream.
+ * For TX/RX streams DMA registers programming for SDW1 instance, it uses ACP_P1_AUDIO1 register
+ * set as per hardware register documentation
+ */
 static struct sdw_dma_ring_buf_reg sdw1_dma_ring_buf_reg[ACP63_SDW1_DMA_MAX_STREAMS] =  {
 	{ACP_P1_AUDIO1_TX_DMA_SIZE, ACP_P1_AUDIO1_TX_FIFOADDR, ACP_P1_AUDIO1_TX_FIFOSIZE,
 	 ACP_P1_AUDIO1_TX_RINGBUFSIZE, ACP_P1_AUDIO1_TX_RINGBUFADDR,
@@ -59,6 +64,12 @@ static u32 sdw0_dma_enable_reg[ACP63_SDW0_DMA_MAX_STREAMS] = {
 	ACP_SW0_AUDIO2_RX_EN,
 };
 
+/*
+ * SDW1 instance supports one TX stream and one RX stream.
+ * For TX/RX streams DMA enable register programming for SDW1 instance,
+ * it uses ACP_SW1_AUDIO1_TX_EN and ACP_SW1_AUDIO1_RX_EN registers
+ * as per hardware register documentation.
+ */
 static u32 sdw1_dma_enable_reg[ACP63_SDW1_DMA_MAX_STREAMS] = {
 	ACP_SW1_AUDIO1_TX_EN,
 	ACP_SW1_AUDIO1_RX_EN,