| 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; |
| 90 | |
