target/linux/xburst/patches-3.8/0016-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 --- a/sound/soc/jz4740/jz4740-pcm.c
  17 +++ b/sound/soc/jz4740/jz4740-pcm.c
  18 @@ -31,6 +31,7 @@
  19
  20  struct jz4740_runtime_data {
  21         unsigned long dma_period;
  22 +       unsigned long dma_period_left;
  23         dma_addr_t dma_start;
  24         dma_addr_t dma_pos;
  25         dma_addr_t dma_end;
  26 @@ -67,10 +68,13 @@ static void jz4740_pcm_start_transfer(st
  27         if (prtd->dma_pos == prtd->dma_end)
  28                 prtd->dma_pos = prtd->dma_start;
  29
  30 -       if (prtd->dma_pos + prtd->dma_period > prtd->dma_end)
  31 +       if (prtd->dma_period_left == 0)
  32 +               prtd->dma_period_left = prtd->dma_period;
  33 +
  34 +       if (prtd->dma_pos + prtd->dma_period_left > prtd->dma_end)
  35                 count = prtd->dma_end - prtd->dma_pos;
  36         else
  37 -               count = prtd->dma_period;
  38 +               count = prtd->dma_period_left;
  39
  40         jz4740_dma_disable(prtd->dma);
  41
  42 @@ -85,6 +89,7 @@ static void jz4740_pcm_start_transfer(st
  43         jz4740_dma_set_transfer_count(prtd->dma, count);
  44
  45         prtd->dma_pos += count;
  46 +       prtd->dma_period_left -= count;
  47
  48         jz4740_dma_enable(prtd->dma);
  49  }
  50 @@ -96,7 +101,8 @@ static void jz4740_pcm_dma_transfer_done
  51         struct snd_pcm_runtime *runtime = substream->runtime;
  52         struct jz4740_runtime_data *prtd = runtime->private_data;
  53
  54 -       snd_pcm_period_elapsed(substream);
  55 +       if (prtd->dma_period_left == 0)
  56 +               snd_pcm_period_elapsed(substream);
  57
  58         jz4740_pcm_start_transfer(prtd, substream);
  59  }
  60 @@ -133,6 +139,7 @@ static int jz4740_pcm_hw_params(struct s
  61         runtime->dma_bytes = params_buffer_bytes(params);
  62
  63         prtd->dma_period = params_period_bytes(params);
  64 +       prtd->dma_period_left = 0;
  65         prtd->dma_start = runtime->dma_addr;
  66         prtd->dma_pos = prtd->dma_start;
  67         prtd->dma_end = prtd->dma_start + runtime->dma_bytes;
  68 @@ -160,6 +167,7 @@ static int jz4740_pcm_prepare(struct snd
  69         if (!prtd->dma)
  70                 return -EBUSY;
  71
  72 +       prtd->dma_period_left = 0;
  73         prtd->dma_pos = prtd->dma_start;
  74
  75         return 0;
  76 @@ -219,6 +227,13 @@ static int jz4740_pcm_open(struct snd_pc
  77         if (prtd == NULL)
  78                 return -ENOMEM;
  79
  80 +       /* Force period and buffer size to be a multiple of the DMA transfer
  81 +        * size, which is 16 bytes. */
  82 +       snd_pcm_hw_constraint_step(runtime, 0,
  83 +                                  SNDRV_PCM_HW_PARAM_PERIOD_BYTES, 16);
  84 +       snd_pcm_hw_constraint_step(runtime, 0,
  85 +                                  SNDRV_PCM_HW_PARAM_BUFFER_BYTES, 16);
  86 +
  87         snd_soc_set_runtime_hwparams(substream, &jz4740_pcm_hardware);
  88
  89         runtime->private_data = prtd;