[alsa-devel] [PATCH] MIPS: Fixups of ALSA memory maps

Wu Zhangjin wuzhangjin at gmail.com
Mon Nov 16 17:48:14 CET 2009

Hi, All

Seems this is MIPS specific, but it's not that easy to move this patch
into the arch/mips part, So, any better solution?

Thanks & Regards,
       Wu Zhangjin


The user application mmap audio dma regions must be dma-coherent. This
patch fix it.

Without this patch, artsd will fail on boot, and mplayer will exit with
"Segmentation fault". (this happens on YeeLoong netbook, fuloong2f
mini pc with snd_cs5535 audio card)

This is originally from the to-mips branch of
http://dev.lemote.com/code/linux_loongson, and contributed by Yanhua
from Lemote Inc.

Reported-by: qiaochong <qiaochong at gmail.com>
Signed-off-by: Wu Zhangjin <wuzj at lemote.com>
 sound/core/pcm_native.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/sound/core/pcm_native.c b/sound/core/pcm_native.c
index ab73edf..2779b9a 100644
--- a/sound/core/pcm_native.c
+++ b/sound/core/pcm_native.c
@@ -3087,7 +3087,11 @@ static int snd_pcm_mmap_data_fault(struct vm_area_struct *area,
 			return VM_FAULT_SIGBUS;
 	} else {
 		vaddr = runtime->dma_area + offset;
+#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT)
+		page = virt_to_page(CAC_ADDR(vaddr));
 		page = virt_to_page(vaddr);
 	vmf->page = page;
@@ -3202,6 +3206,11 @@ static int snd_pcm_mmap(struct file *file, struct vm_area_struct *area)
 	if (PCM_RUNTIME_CHECK(substream))
 		return -ENXIO;
+#if defined(__mips__) && defined(CONFIG_DMA_NONCOHERENT)
+	/* all mmap using uncached mode */
+	area->vm_page_prot = pgprot_noncached(area->vm_page_prot);
+	area->vm_flags |= (VM_RESERVED | VM_IO);
 	offset = area->vm_pgoff << PAGE_SHIFT;
 	switch (offset) {

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