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-rw-r--r--sound/core/pcm_memory.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/sound/core/pcm_memory.c b/sound/core/pcm_memory.c
index 859b118..a6d4280 100644
--- a/sound/core/pcm_memory.c
+++ b/sound/core/pcm_memory.c
@@ -324,6 +324,32 @@ struct page *snd_pcm_sgbuf_ops_page(struct snd_pcm_substream *substream, unsigne
EXPORT_SYMBOL(snd_pcm_sgbuf_ops_page);
+/*
+ * compute the max chunk size with continuous pages on sg-buffer
+ */
+unsigned int snd_pcm_sgbuf_get_chunk_size(struct snd_pcm_substream *substream,
+ unsigned int ofs, unsigned int size)
+{
+ struct snd_sg_buf *sg = snd_pcm_substream_sgbuf(substream);
+ unsigned int start, end, pg;
+
+ start = ofs >> PAGE_SHIFT;
+ end = (ofs + size - 1) >> PAGE_SHIFT;
+ /* check page continuity */
+ pg = sg->table[start].addr >> PAGE_SHIFT;
+ for (;;) {
+ start++;
+ if (start > end)
+ break;
+ pg++;
+ if ((sg->table[start].addr >> PAGE_SHIFT) != pg)
+ return (start << PAGE_SHIFT) - ofs;
+ }
+ /* ok, all on continuous pages */
+ return size;
+}
+EXPORT_SYMBOL(snd_pcm_sgbuf_get_chunk_size);
+
/**
* snd_pcm_lib_malloc_pages - allocate the DMA buffer
* @substream: the substream to allocate the DMA buffer to