target/linux/xburst/patches-3.2/0016-ASoC-JZ4740-Support-buffer-size-that-is-not-a-multip.patch

   1 From 8a5087fe59e31efb8641e704058328997c3c8ff1 Mon Sep 17 00:00:00 2001
   2 From: Maarten ter Huurne <maarten@treewalker.org>
   3 Date: Wed, 10 Aug 2011 00:25:11 +0200
   4 Subject: [PATCH 16/21] ASoC: JZ4740: Support buffer size that is not a
   5  multiple of period size.
   6
   7 This fixes glitches triggered by libao, which sets time-based intervals
   8 instead of byte-based intervals like SDL does.
   9
  10 Thanks to Paul Cercueil for figuring out that the buffer size was causing
  11 the glitches and to Lars Clausen for helping me write the fix.
  12 ---
  13  sound/soc/jz4740/jz4740-pcm.c |   21 ++++++++++++++++++---
  14  1 files changed, 18 insertions(+), 3 deletions(-)
  15
  16 diff --git a/sound/soc/jz4740/jz4740-pcm.c b/sound/soc/jz4740/jz4740-pcm.c
  17 index d1989cd..1f9a005 100644
  18 --- a/sound/soc/jz4740/jz4740-pcm.c
  19 +++ b/sound/soc/jz4740/jz4740-pcm.c
  20 @@ -31,6 +31,7 @@
  21
  22  struct jz4740_runtime_data {
  23         unsigned long dma_period;
  24 +       unsigned long dma_period_left;
  25         dma_addr_t dma_start;
  26         dma_addr_t dma_pos;
  27         dma_addr_t dma_end;
  28 @@ -67,10 +68,13 @@ static void jz4740_pcm_start_transfer(struct jz4740_runtime_data *prtd,
  29         if (prtd->dma_pos == prtd->dma_end)
  30                 prtd->dma_pos = prtd->dma_start;
  31
  32 -       if (prtd->dma_pos + prtd->dma_period > prtd->dma_end)
  33 +       if (prtd->dma_period_left == 0)
  34 +               prtd->dma_period_left = prtd->dma_period;
  35 +
  36 +       if (prtd->dma_pos + prtd->dma_period_left > prtd->dma_end)
  37                 count = prtd->dma_end - prtd->dma_pos;
  38         else
  39 -               count = prtd->dma_period;
  40 +               count = prtd->dma_period_left;
  41
  42         jz4740_dma_disable(prtd->dma);
  43
  44 @@ -85,6 +89,7 @@ static void jz4740_pcm_start_transfer(struct jz4740_runtime_data *prtd,
  45         jz4740_dma_set_transfer_count(prtd->dma, count);
  46
  47         prtd->dma_pos += count;
  48 +       prtd->dma_period_left -= count;
  49
  50         jz4740_dma_enable(prtd->dma);
  51  }
  52 @@ -96,7 +101,8 @@ static void jz4740_pcm_dma_transfer_done(struct jz4740_dma_chan *dma, int err,
  53         struct snd_pcm_runtime *runtime = substream->runtime;
  54         struct jz4740_runtime_data *prtd = runtime->private_data;
  55
  56 -       snd_pcm_period_elapsed(substream);
  57 +       if (prtd->dma_period_left == 0)
  58 +               snd_pcm_period_elapsed(substream);
  59
  60         jz4740_pcm_start_transfer(prtd, substream);
  61  }
  62 @@ -133,6 +139,7 @@ static int jz4740_pcm_hw_params(struct snd_pcm_substream *substream,
  63         runtime->dma_bytes = params_buffer_bytes(params);
  64
  65         prtd->dma_period = params_period_bytes(params);
  66 +       prtd->dma_period_left = 0;
  67         prtd->dma_start = runtime->dma_addr;
  68         prtd->dma_pos = prtd->dma_start;
  69         prtd->dma_end = prtd->dma_start + runtime->dma_bytes;
  70 @@ -160,6 +167,7 @@ static int jz4740_pcm_prepare(struct snd_pcm_substream *substream)
  71         if (!prtd->dma)
  72                 return -EBUSY;
  73
  74 +       prtd->dma_period_left = 0;
  75         prtd->dma_pos = prtd->dma_start;
  76
  77         return 0;
  78 @@ -219,6 +227,13 @@ static int jz4740_pcm_open(struct snd_pcm_substream *substream)
  79         if (prtd == NULL)
  80                 return -ENOMEM;
  81
  82 +       /* Force period and buffer size to be a multiple of the DMA transfer
  83 +        * size, which is 16 bytes. */
  84 +       snd_pcm_hw_constraint_step(runtime, 0,
  85 +                                  SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 16);
  86 +       snd_pcm_hw_constraint_step(runtime, 0,
  87 +                                  SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 16);
  88 +
  89         snd_soc_set_runtime_hwparams(substream, &jz4740_pcm_hardware);
  90
  91         runtime->private_data = prtd;
  92 --
  93 1.7.5.4
  94