[alsa-devel] [PATCH 3/5] ALSA: pcm - fix page conversion on non-coherent MIPS arch

Takashi Iwai tiwai at suse.de
Thu Nov 26 16:13:06 CET 2009

The non-coherent MIPS arch doesn't give the correct address by a simple
virt_to_page() for pages allocated via dma_alloc_coherent().

Original patch by Wu Zhangjin <wuzj at lemote.com>.  A proper check of the
buffer allocation type was added to avoid the wrong conversion.

Note that this doesn't fix perfectly: the pages should be marked with
proper pgprot value.  This will be done in a future implementation like
the conversion to dma_mmap_coherent().

Signed-off-by: Takashi Iwai <tiwai at suse.de>
 sound/core/pcm_native.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index c906be2..e48c5f6 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3066,6 +3066,10 @@ static inline struct page *
 snd_pcm_default_page_ops(struct snd_pcm_substream *substream, unsigned long ofs)
 	void *vaddr = substream->runtime->dma_area + ofs;
+#if defined(CONFIG_MIPS) && defined(CONFIG_DMA_NONCOHERENT)
+	if (substream->dma_buffer.dev.type == SNDRV_DMA_TYPE_DEV)
+		return virt_to_page(CAC_ADDR(vaddr));
 	return virt_to_page(vaddr);

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