commit cc6a8acdeee932f6911d8b236d2c7d6bcc4616f6
author Takashi Iwai <tiwai@suse.de> Tue Jun 17 16:39:06 2008 +0200
committer Takashi Iwai <tiwai@suse.de> Wed Jul 08 14:20:20 2009 +0200
tree ebaadf1a406cf073fd4ce59d5f1f20d499f9cde1
parent 8e4a718ff38d8539938ec3421935904c27e00c39

ALSA: Fix SG-buffer DMA with non-coherent architectures

Using SG-buffers with dma_alloc_coherent() is often very inefficient
on non-coherent architectures because a tracking record could be
allocated in addition for each dma_alloc_coherent() call.
Instead, simply disable SG-buffers but just allocate normal continuous
buffers on non-supported (currently all but x86) architectures.

Signed-off-by: Takashi Iwai <tiwai@suse.de>

sound/core/Kconfig

diff --git a/sound/core/Kconfig b/sound/core/Kconfig
index 6061fb5..c15682a 100644
--- a/sound/core/Kconfig
+++ b/sound/core/Kconfig
@@ -206,4 +206,8 @@
 config SND_VMASTER
 	bool
 
+config SND_DMA_SGBUF
+	def_bool y
+	depends on X86
+
 source "sound/core/seq/Kconfig"

sound/core/Makefile

diff --git a/sound/core/Makefile b/sound/core/Makefile
index 4229052..350a08d 100644
--- a/sound/core/Makefile
+++ b/sound/core/Makefile
@@ -13,7 +13,7 @@
 		pcm_memory.o
 
 snd-page-alloc-y := memalloc.o
-snd-page-alloc-$(CONFIG_HAS_DMA) += sgbuf.o
+snd-page-alloc-$(CONFIG_SND_DMA_SGBUF) += sgbuf.o
 
 snd-rawmidi-objs  := rawmidi.o
 snd-timer-objs    := timer.o

sound/core/memalloc.c

diff --git a/sound/core/memalloc.c b/sound/core/memalloc.c
index 1b3534d..9e92441 100644
--- a/sound/core/memalloc.c
+++ b/sound/core/memalloc.c
@@ -199,6 +199,8 @@
 	case SNDRV_DMA_TYPE_DEV:
 		dmab->area = snd_malloc_dev_pages(device, size, &dmab->addr);
 		break;
+#endif
+#ifdef CONFIG_SND_DMA_SGBUF
 	case SNDRV_DMA_TYPE_DEV_SG:
 		snd_malloc_sgbuf_pages(device, size, dmab, NULL);
 		break;
@@ -269,6 +271,8 @@
 	case SNDRV_DMA_TYPE_DEV:
 		snd_free_dev_pages(dmab->dev.dev, dmab->bytes, dmab->area, dmab->addr);
 		break;
+#endif
+#ifdef CONFIG_SND_DMA_SGBUF
 	case SNDRV_DMA_TYPE_DEV_SG:
 		snd_free_sgbuf_pages(dmab);
 		break;

sound/core/pcm_memory.c

diff --git a/sound/core/pcm_memory.c b/sound/core/pcm_memory.c
index a6d4280..caa7796 100644
--- a/sound/core/pcm_memory.c
+++ b/sound/core/pcm_memory.c
@@ -304,6 +304,7 @@
 
 EXPORT_SYMBOL(snd_pcm_lib_preallocate_pages_for_all);
 
+#ifdef CONFIG_SND_DMA_SGBUF
 /**
  * snd_pcm_sgbuf_ops_page - get the page struct at the given offset
  * @substream: the pcm substream instance
@@ -349,6 +350,7 @@
 	return size;
 }
 EXPORT_SYMBOL(snd_pcm_sgbuf_get_chunk_size);
+#endif /* CONFIG_SND_DMA_SGBUF */
 
 /**
  * snd_pcm_lib_malloc_pages - allocate the DMA buffer