diff options
Diffstat (limited to 'sound/core/pcm_memory.c')
| -rw-r--r-- | sound/core/pcm_memory.c | 26 |
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 |