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: NTakashi Iwai <tiwai@suse.de>

No longer used.
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Most hardwares have limited buffer-descriptor table length.  This
also restricts the max buffer size of the sound driver.
For example, snd-hda-intel has 1MB buffer size limit, and this is
because it can have at most 256 BDL entries.  For supporting larger
buffers, we need to allocate larger pages even for sg-buffers.

This patch changes the sgbuf allocation code to try to allocate
larger pages first.  At each head of the allocated pages, the
number of allocated pages is stored in the lowest bits of the
corresponding entry of the table addr field.  This change isn't
visible as long as the driver uses snd_sgbuf_get_addr() helper.

Also, the patch adds a new function, snd_pcm_sgbuf_get_chunk_size().
This returns the size of the chunk on continuous pages starting at
the given position offset.  If the chunk reaches to a non-continuous
page, it returns the size to the boundary.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@perex.cz>

Clean up SG-buffer helper functions and macros.  Helpers take substream
as arguments now.
Signed-off-by: NTakashi Iwai <tiwai@suse.de>
Signed-off-by: NJaroslav Kysela <perex@perex.cz>

Signed-off-by: NJaroslav Kysela <perex@perex.cz>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!