[ALSA] usb-audio: use vmalloc for the PCM buffer
USB generic driver
With the double buffering, we no longer need contiguous memory for the
PCM buffer, so we can use vmalloc() instead of the preallocation
functions, and increase the maximum size to 256 KB.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
diff --git a/sound/usb/usbaudio.c b/sound/usb/usbaudio.c
index 13ff66b..5aa5fe6 100644
--- a/sound/usb/usbaudio.c
+++ b/sound/usb/usbaudio.c
@@ -46,6 +46,7 @@
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/usb.h>
+#include <linux/vmalloc.h>
#include <linux/moduleparam.h>
#include <sound/core.h>
#include <sound/info.h>
@@ -676,6 +677,42 @@
}
+/* get the physical page pointer at the given offset */
+static struct page *snd_pcm_get_vmalloc_page(snd_pcm_substream_t *subs,
+ unsigned long offset)
+{
+ void *pageptr = subs->runtime->dma_area + offset;
+ return vmalloc_to_page(pageptr);
+}
+
+/* allocate virtual buffer; may be called more than once */
+static int snd_pcm_alloc_vmalloc_buffer(snd_pcm_substream_t *subs, size_t size)
+{
+ snd_pcm_runtime_t *runtime = subs->runtime;
+ if (runtime->dma_area) {
+ if (runtime->dma_bytes >= size)
+ return 0; /* already large enough */
+ vfree_nocheck(runtime->dma_area);
+ }
+ runtime->dma_area = vmalloc_nocheck(size);
+ if (! runtime->dma_area)
+ return -ENOMEM;
+ runtime->dma_bytes = size;
+ return 0;
+}
+
+/* free virtual buffer; may be called more than once */
+static int snd_pcm_free_vmalloc_buffer(snd_pcm_substream_t *subs)
+{
+ snd_pcm_runtime_t *runtime = subs->runtime;
+ if (runtime->dma_area) {
+ vfree_nocheck(runtime->dma_area);
+ runtime->dma_area = NULL;
+ }
+ return 0;
+}
+
+
/*
* unlink active urbs.
*/
@@ -1311,7 +1348,8 @@
unsigned int channels, rate, format;
int ret, changed;
- ret = snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
+ ret = snd_pcm_alloc_vmalloc_buffer(substream,
+ params_buffer_bytes(hw_params));
if (ret < 0)
return ret;
@@ -1367,7 +1405,7 @@
subs->cur_rate = 0;
subs->period_bytes = 0;
release_substream_urbs(subs, 0);
- return snd_pcm_lib_free_pages(substream);
+ return snd_pcm_free_vmalloc_buffer(substream);
}
/*
@@ -1406,7 +1444,7 @@
.info = (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_BLOCK_TRANSFER |
SNDRV_PCM_INFO_MMAP_VALID),
- .buffer_bytes_max = (128*1024),
+ .buffer_bytes_max = (256*1024),
.period_bytes_min = 64,
.period_bytes_max = (128*1024),
.periods_min = 2,
@@ -1418,7 +1456,7 @@
.info = (SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_BLOCK_TRANSFER |
SNDRV_PCM_INFO_MMAP_VALID),
- .buffer_bytes_max = (128*1024),
+ .buffer_bytes_max = (256*1024),
.period_bytes_min = 64,
.period_bytes_max = (128*1024),
.periods_min = 2,
@@ -1810,6 +1848,7 @@
.prepare = snd_usb_pcm_prepare,
.trigger = snd_usb_pcm_trigger,
.pointer = snd_usb_pcm_pointer,
+ .page = snd_pcm_get_vmalloc_page,
};
static snd_pcm_ops_t snd_usb_capture_ops = {
@@ -1821,6 +1860,7 @@
.prepare = snd_usb_pcm_prepare,
.trigger = snd_usb_pcm_trigger,
.pointer = snd_usb_pcm_pointer,
+ .page = snd_pcm_get_vmalloc_page,
};
@@ -2048,10 +2088,6 @@
subs->ops = audio_urb_ops[stream];
else
subs->ops = audio_urb_ops_high_speed[stream];
- snd_pcm_lib_preallocate_pages(as->pcm->streams[stream].substream,
- SNDRV_DMA_TYPE_CONTINUOUS,
- snd_dma_continuous_data(GFP_NOIO),
- 64 * 1024, 128 * 1024);
snd_pcm_set_ops(as->pcm, stream,
stream == SNDRV_PCM_STREAM_PLAYBACK ?
&snd_usb_playback_ops : &snd_usb_capture_ops);
@@ -2097,7 +2133,6 @@
snd_usb_stream_t *stream = pcm->private_data;
if (stream) {
stream->pcm = NULL;
- snd_pcm_lib_preallocate_free_for_all(pcm);
snd_usb_audio_stream_free(stream);
}
}