[alsa-devel] Applied "ASoC: amd: Modified DMA transfer Mechanism for Playback" to the asoc tree

[Mark Brown]

The patch

   ASoC: amd: Modified DMA transfer Mechanism for Playback

has been applied to the asoc tree at

   https://git.kernel.org/pub/scm/linux/kernel/git/broonie/sound.git 

All being well this means that it will be integrated into the linux-next
tree (usually sometime in the next 24 hours) and sent to Linus during
the next merge window (or sooner if it is a bug fix), however if
problems are discovered then the patch may be dropped or reverted.  

You may get further e-mails resulting from automated or manual testing
and review of the tree, please engage with people reporting problems and
send followup patches addressing any issues that are reported if needed.

If any updates are required or you are submitting further changes they
should be sent as incremental updates against current git, existing
patches will not be replaced.

Please add any relevant lists and maintainers to the CCs when replying
to this mail.

Thanks,
Mark

>From 31c45b3e8d0ecc3a5cbfbf3dfe18adeab2f17a48 Mon Sep 17 00:00:00 2001
From: Vijendar Mukunda <Vijendar.Mukunda at amd.com>
Date: Thu, 9 Nov 2017 12:35:52 -0500
Subject: [PATCH] ASoC: amd: Modified DMA transfer Mechanism for Playback

Before rendering starts, DMA driver copies full buffer valid data
to ACP SRAM for the first time, after that ACP SRAM to I2S
FIFO DMA will be initiated. After rendering first half of ACP SRAM,
IOC will be raised then Audio data will be copied from first half of
System Memory to first half of ACP SRAM. Similarly after rendering
second half of ACP SRAM, IOC will be raised then Audio Data will be
copied from second half of the System Memory to second half of the
ACP SRAM in ping-pong way till rendering stops.

Old design introducing latency issues resulting stutter sound observed
during playback.

Signed-off-by: Vijendar Mukunda <Vijendar.Mukunda at amd.com>
Signed-off-by: Akshu Agrawal <Akshu.Agrawal at amd.com>
Signed-off-by: Alex Deucher <alexander.deucher at amd.com>
Signed-off-by: Mark Brown <broonie at kernel.org>
---
 sound/soc/amd/acp-pcm-dma.c | 27 +++++----------------------
 1 file changed, 5 insertions(+), 22 deletions(-)

diff --git a/sound/soc/amd/acp-pcm-dma.c b/sound/soc/amd/acp-pcm-dma.c
index ef7e98ad960c..9f521a55d610 100644
--- a/sound/soc/amd/acp-pcm-dma.c
+++ b/sound/soc/amd/acp-pcm-dma.c
@@ -193,8 +193,8 @@ static void set_acp_sysmem_dma_descriptors(void __iomem *acp_mmio,
 		dmadscr[i].xfer_val = 0;
 		if (direction == SNDRV_PCM_STREAM_PLAYBACK) {
 			dma_dscr_idx = PLAYBACK_START_DMA_DESCR_CH12 + i;
-			dmadscr[i].dest = ACP_SHARED_RAM_BANK_1_ADDRESS +
-					(size / 2) - (i * (size/2));
+			dmadscr[i].dest = ACP_SHARED_RAM_BANK_1_ADDRESS
+					+ (i * (size/2));
 			dmadscr[i].src = ACP_INTERNAL_APERTURE_WINDOW_0_ADDRESS
 				+ (pte_offset * SZ_4K) + (i * (size/2));
 			switch (asic_type) {
@@ -655,9 +655,9 @@ static irqreturn_t dma_irq_handler(int irq, void *arg)
 		valid_irq = true;
 		if (acp_reg_read(acp_mmio, mmACP_DMA_CUR_DSCR_13) ==
 				PLAYBACK_START_DMA_DESCR_CH13)
-			dscr_idx = PLAYBACK_START_DMA_DESCR_CH12;
-		else
 			dscr_idx = PLAYBACK_END_DMA_DESCR_CH12;
+		else
+			dscr_idx = PLAYBACK_START_DMA_DESCR_CH12;
 		config_acp_dma_channel(acp_mmio, SYSRAM_TO_ACP_CH_NUM, dscr_idx,
 				       1, 0);
 		acp_dma_start(acp_mmio, SYSRAM_TO_ACP_CH_NUM, false);
@@ -882,23 +882,6 @@ static int acp_dma_prepare(struct snd_pcm_substream *substream)
 		config_acp_dma_channel(rtd->acp_mmio, ACP_TO_I2S_DMA_CH_NUM,
 					PLAYBACK_START_DMA_DESCR_CH13,
 					NUM_DSCRS_PER_CHANNEL, 0);
-		/* Fill ACP SRAM (2 periods) with zeros from System RAM
-		 * which is zero-ed in hw_params
-		*/
-		acp_dma_start(rtd->acp_mmio, SYSRAM_TO_ACP_CH_NUM, false);
-
-		/* ACP SRAM (2 periods of buffer size) is intially filled with
-		 * zeros. Before rendering starts, 2nd half of SRAM will be
-		 * filled with valid audio data DMA'ed from first half of system
-		 * RAM and 1st half of SRAM will be filled with Zeros. This is
-		 * the initial scenario when redering starts from SRAM. Later
-		 * on, 2nd half of system memory will be DMA'ed to 1st half of
-		 * SRAM, 1st half of system memory will be DMA'ed to 2nd half of
-		 * SRAM in ping-pong way till rendering stops.
-		*/
-		config_acp_dma_channel(rtd->acp_mmio, SYSRAM_TO_ACP_CH_NUM,
-					PLAYBACK_START_DMA_DESCR_CH12,
-					1, 0);
 	} else {
 		config_acp_dma_channel(rtd->acp_mmio, ACP_TO_SYSRAM_CH_NUM,
 					CAPTURE_START_DMA_DESCR_CH14,
@@ -913,7 +896,7 @@ static int acp_dma_prepare(struct snd_pcm_substream *substream)
 static int acp_dma_trigger(struct snd_pcm_substream *substream, int cmd)
 {
 	int ret;
-	u32 loops = 1000;
+	u32 loops = 4000;
 	u64 bytescount = 0;
 
 	struct snd_pcm_runtime *runtime = substream->runtime;
-- 
2.15.0