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>

1 files changed, 23 insertions, 0 deletions

diff --git a/include/sound/pcm.h b/include/sound/pcm.h
index 23893523dc8c..1691c7fe35af 100644
--- a/include/sound/pcm.h
+++ b/include/sound/pcm.h
@@ -902,6 +902,7 @@ int snd_pcm_lib_preallocate_pages_for_all(struct snd_pcm *pcm,
 int snd_pcm_lib_malloc_pages(struct snd_pcm_substream *substream, size_t size);
 int snd_pcm_lib_free_pages(struct snd_pcm_substream *substream);
 
+#ifdef CONFIG_SND_DMA_SGBUF
 /*
  * SG-buffer handling
  */
@@ -927,6 +928,28 @@ struct page *snd_pcm_sgbuf_ops_page(struct snd_pcm_substream *substream,
 unsigned int snd_pcm_sgbuf_get_chunk_size(struct snd_pcm_substream *substream,
                                           unsigned int ofs, unsigned int size);
 
+#else /* !SND_DMA_SGBUF */
+/*
+ * fake using a continuous buffer
+ */
+static inline dma_addr_t
+snd_pcm_sgbuf_get_addr(struct snd_pcm_substream *substream, unsigned int ofs)
+{
+        return substream->runtime->dma_addr + ofs;
+}
+
+static inline void *
+snd_pcm_sgbuf_get_ptr(struct snd_pcm_substream *substream, unsigned int ofs)
+{
+        return substream->runtime->dma_area + ofs;
+}
+
+#define snd_pcm_sgbuf_ops_page  NULL
+
+#define snd_pcm_sgbuf_get_chunk_size(subs, ofs, size)   (size)
+
+#endif /* SND_DMA_SGBUF */
+
 /* handle mmap counter - PCM mmap callback should handle this counter properly */
 static inline void snd_pcm_mmap_data_open(struct vm_area_struct *area)
 {