90 lines
2.8 KiB
Diff
90 lines
2.8 KiB
Diff
From 8a5087fe59e31efb8641e704058328997c3c8ff1 Mon Sep 17 00:00:00 2001
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From: Maarten ter Huurne <maarten@treewalker.org>
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Date: Wed, 10 Aug 2011 00:25:11 +0200
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Subject: [PATCH 16/21] ASoC: JZ4740: Support buffer size that is not a
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multiple of period size.
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This fixes glitches triggered by libao, which sets time-based intervals
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instead of byte-based intervals like SDL does.
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Thanks to Paul Cercueil for figuring out that the buffer size was causing
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the glitches and to Lars Clausen for helping me write the fix.
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---
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sound/soc/jz4740/jz4740-pcm.c | 21 ++++++++++++++++++---
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1 files changed, 18 insertions(+), 3 deletions(-)
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--- a/sound/soc/jz4740/jz4740-pcm.c
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+++ b/sound/soc/jz4740/jz4740-pcm.c
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@@ -31,6 +31,7 @@
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struct jz4740_runtime_data {
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unsigned long dma_period;
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+ unsigned long dma_period_left;
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dma_addr_t dma_start;
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dma_addr_t dma_pos;
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dma_addr_t dma_end;
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@@ -67,10 +68,13 @@ static void jz4740_pcm_start_transfer(st
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if (prtd->dma_pos == prtd->dma_end)
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prtd->dma_pos = prtd->dma_start;
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- if (prtd->dma_pos + prtd->dma_period > prtd->dma_end)
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+ if (prtd->dma_period_left == 0)
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+ prtd->dma_period_left = prtd->dma_period;
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+
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+ if (prtd->dma_pos + prtd->dma_period_left > prtd->dma_end)
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count = prtd->dma_end - prtd->dma_pos;
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else
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- count = prtd->dma_period;
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+ count = prtd->dma_period_left;
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jz4740_dma_disable(prtd->dma);
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@@ -85,6 +89,7 @@ static void jz4740_pcm_start_transfer(st
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jz4740_dma_set_transfer_count(prtd->dma, count);
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prtd->dma_pos += count;
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+ prtd->dma_period_left -= count;
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jz4740_dma_enable(prtd->dma);
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}
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@@ -96,7 +101,8 @@ static void jz4740_pcm_dma_transfer_done
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struct snd_pcm_runtime *runtime = substream->runtime;
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struct jz4740_runtime_data *prtd = runtime->private_data;
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- snd_pcm_period_elapsed(substream);
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+ if (prtd->dma_period_left == 0)
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+ snd_pcm_period_elapsed(substream);
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jz4740_pcm_start_transfer(prtd, substream);
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}
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@@ -133,6 +139,7 @@ static int jz4740_pcm_hw_params(struct s
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runtime->dma_bytes = params_buffer_bytes(params);
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prtd->dma_period = params_period_bytes(params);
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+ prtd->dma_period_left = 0;
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prtd->dma_start = runtime->dma_addr;
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prtd->dma_pos = prtd->dma_start;
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prtd->dma_end = prtd->dma_start + runtime->dma_bytes;
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@@ -160,6 +167,7 @@ static int jz4740_pcm_prepare(struct snd
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if (!prtd->dma)
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return -EBUSY;
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+ prtd->dma_period_left = 0;
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prtd->dma_pos = prtd->dma_start;
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return 0;
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@@ -219,6 +227,13 @@ static int jz4740_pcm_open(struct snd_pc
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if (prtd == NULL)
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return -ENOMEM;
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+ /* Force period and buffer size to be a multiple of the DMA transfer
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+ * size, which is 16 bytes. */
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+ snd_pcm_hw_constraint_step(runtime, 0,
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+ SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 16);
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+ snd_pcm_hw_constraint_step(runtime, 0,
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+ SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 16);
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+
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snd_soc_set_runtime_hwparams(substream, &jz4740_pcm_hardware);
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runtime->private_data = prtd;
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