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