Currently, The fixed 512KB prealloc buffer size is too larger for
tiny memory kernel (such as 16MB memory). This patch adds the module
option "prealloc_buffer_size_kbytes" to specify prealloc buffer size.
It's suitable for cards which use the generic dmaengine pcm driver
with no config.
Signed-off-by: Sugar Zhang <sugar.zhang@xxxxxxxxxxxxxx>
---
Documentation/sound/alsa-configuration.rst | 9 +++++++++
sound/soc/soc-generic-dmaengine-pcm.c | 6 +++++-
2 files changed, 14 insertions(+), 1 deletion(-)
diff --git a/Documentation/sound/alsa-configuration.rst b/Documentation/sound/alsa-configuration.rst
index 65f6169..34888d4 100644
--- a/Documentation/sound/alsa-configuration.rst
+++ b/Documentation/sound/alsa-configuration.rst
@@ -100,6 +100,15 @@ amidi_map
MIDI device number maps assigned to the 2st OSS device;
Default: 1
+Module snd-soc-core
+-------------------
+
+The soc core module. It is used by all ALSA card drivers.
+It takes the following options which have global effects.
+
+prealloc_buffer_size_kbytes
+ Specify prealloc buffer size in kbytes (default: 512).
+
Common parameters for top sound card modules
--------------------------------------------
diff --git a/sound/soc/soc-generic-dmaengine-pcm.c b/sound/soc/soc-generic-dmaengine-pcm.c
index 4aa48c7..c54c8ca 100644
--- a/sound/soc/soc-generic-dmaengine-pcm.c
+++ b/sound/soc/soc-generic-dmaengine-pcm.c
@@ -15,6 +15,10 @@
#include <sound/dmaengine_pcm.h>
+static unsigned int prealloc_buffer_size_kbytes = 512;
+module_param(prealloc_buffer_size_kbytes, uint, 0444);
+MODULE_PARM_DESC(prealloc_buffer_size_kbytes, "Preallocate DMA buffer size (KB).");
+
/*
* The platforms dmaengine driver does not support reporting the amount of
* bytes that are still left to transfer.
@@ -237,7 +241,7 @@ static int dmaengine_pcm_new(struct snd_soc_component *component,
prealloc_buffer_size = config->prealloc_buffer_size;
max_buffer_size = config->pcm_hardware->buffer_bytes_max;
} else {
- prealloc_buffer_size = 512 * 1024;
+ prealloc_buffer_size = prealloc_buffer_size_kbytes * 1024;
max_buffer_size = SIZE_MAX;
}
--
2.7.4
