linux-kernel - [PATCH 02/11] ASoC: omap-mcbsp: Use sDMA packet mode instead of frame mode

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Date:	Wed, 12 Sep 2012 14:46:58 +0300
From:	Peter Ujfalusi <peter.ujfalusi@...com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Liam Girdwood <lrg@...com>, Tony Lindgren <tony@...mide.com>,
	Russell King <rmk+kernel@....linux.org.uk>,
	Vinod Koul <vinod.koul@...el.com>, Dan Williams <djbw@...com>,
	Jarkko Nikula <jarkko.nikula@...mer.com>
Cc:	alsa-devel@...a-project.org, linux-omap@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Janusz Krzysztofik <jkrzyszt@....icnet.pl>,
	Ricardo Neri <ricardo.neri@...com>
Subject: [PATCH 02/11] ASoC: omap-mcbsp: Use sDMA packet mode instead of frame mode

When McBSP is configured in threshold mode we can use sDMA packet mode in
all cases.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@...com>
---
 sound/soc/omap/omap-mcbsp.c | 47 ++++++++++++++++-----------------------------
 1 file changed, 17 insertions(+), 30 deletions(-)

diff --git a/sound/soc/omap/omap-mcbsp.c b/sound/soc/omap/omap-mcbsp.c
index 2e91a86..fe3debc 100644
--- a/sound/soc/omap/omap-mcbsp.c
+++ b/sound/soc/omap/omap-mcbsp.c
@@ -81,9 +81,6 @@ static void omap_mcbsp_set_threshold(struct snd_pcm_substream *substream)
 	 */
 	if (dma_data->packet_size)
 		words = dma_data->packet_size;
-	else if (mcbsp->dma_op_mode == MCBSP_DMA_MODE_THRESHOLD)
-		words = snd_pcm_lib_period_bytes(substream) /
-						(mcbsp->wlen / 8);
 	else
 		words = 1;
 
@@ -251,6 +248,7 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 		dma_data->set_threshold = omap_mcbsp_set_threshold;
 		if (mcbsp->dma_op_mode == MCBSP_DMA_MODE_THRESHOLD) {
 			int period_words, max_thrsh;
+			int divider = 0;
 
 			period_words = params_period_bytes(params) / (wlen / 8);
 			if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
@@ -258,34 +256,23 @@ static int omap_mcbsp_dai_hw_params(struct snd_pcm_substream *substream,
 			else
 				max_thrsh = mcbsp->max_rx_thres;
 			/*
-			 * If the period contains less or equal number of words,
-			 * we are using the original threshold mode setup:
-			 * McBSP threshold = sDMA frame size = period_size
-			 * Otherwise we switch to sDMA packet mode:
-			 * McBSP threshold = sDMA packet size
-			 * sDMA frame size = period size
+			 * Use sDMA packet mode if McBSP is in threshold mode:
+			 * If period words less than the FIFO size the packet
+			 * size is set to the number of period words, otherwise
+			 * Look for the biggest threshold value which divides
+			 * the period size evenly.
 			 */
-			if (period_words > max_thrsh) {
-				int divider = 0;
-
-				/*
-				 * Look for the biggest threshold value, which
-				 * divides the period size evenly.
-				 */
-				divider = period_words / max_thrsh;
-				if (period_words % max_thrsh)
-					divider++;
-				while (period_words % divider &&
-					divider < period_words)
-					divider++;
-				if (divider == period_words)
-					return -EINVAL;
-
-				pkt_size = period_words / divider;
-				sync_mode = OMAP_DMA_SYNC_PACKET;
-			} else {
-				sync_mode = OMAP_DMA_SYNC_FRAME;
-			}
+			divider = period_words / max_thrsh;
+			if (period_words % max_thrsh)
+				divider++;
+			while (period_words % divider &&
+				divider < period_words)
+				divider++;
+			if (divider == period_words)
+				return -EINVAL;
+
+			pkt_size = period_words / divider;
+			sync_mode = OMAP_DMA_SYNC_PACKET;
 		} else if (channels > 1) {
 			/* Use packet mode for non mono streams */
 			pkt_size = channels;
-- 
1.7.12

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