At Tue, 13 Apr 2010 12:58:54 +0800,
Wu Zhangjin wrote:
> Hi, Ralf and Takashi
> Seems Takashi have sent the MIPS specific dma_mmap_coherent() at 18 Aug
> But that patch have not been accepted since it was not suitable to all
> of the MIPS variants.
> Without that patch, the ALSA output will be broken in some of the MIPS
> variants, can we make the implementation in the above url be weak, then
> the particular MIPS variants can override it with their own versions but
> the common MIPS variants can share it to fix the ALSA problem?
> I have attached a change of the above patch, which is applicable to the
> linux-2.6.33 and linux-2.6.34-rcX and I have tested it on my YeeLoong
> netbook, the following command function well with it.
> $ mplayer -ao alsa file.mp3
> but without it, the ALSA output is broken.
Hm, which driver/device are you using? Also, how is it broken?
There is already a low-level hack in sound/core/pcm_native.c for MIPS,
so I thought the kernel oops should have been avoided, at least.
Maybe still pgprot_noncached() is missing, though.
> Wu Zhangjin
> [2 0001-MIPS-Implement-dma_mmap_coherent-for-ALSA-audio-outp.patch
> <text/x-patch; UTF-8 (7bit)>]
> >From a6ee304febbd609d2936dd5b33a16482ef224c97 Mon Sep 17 00:00:00 2001
> From: Wu Zhangjin <firstname.lastname@example.org>
> Date: Sun, 11 Apr 2010 03:58:13 +0800
> Subject: [PATCH] MIPS: Implement dma_mmap_coherent() for ALSA audio output
> A lazy version of dma_mmap_coherent() implementation for MIPS.
> Without this patch, the ALSA sound output of MIPS is broken:
> $ mplayer -ao alsa file.mp3
> (This patch was sent out by Takashi Iwai at '18 Aug 2008' but not have
> been applied yet for it is not suitable for all MIPS variants. If you
> need more info, please access:
> Signed-off-by: Takashi Iwai <email@example.com>
> arch/mips/include/asm/dma-mapping.h | 4 ++++
> arch/mips/mm/dma-default.c | 13 +++++++++++++
> 2 files changed, 17 insertions(+), 0 deletions(-)
> diff --git a/arch/mips/include/asm/dma-mapping.h
> index 664ba53..c39bfdf 100644
> --- a/arch/mips/include/asm/dma-mapping.h
> +++ b/arch/mips/include/asm/dma-mapping.h
> @@ -74,4 +74,8 @@ extern int dma_is_consistent(struct device *dev, dma_addr_t
> extern void dma_cache_sync(struct device *dev, void *vaddr, size_t size,
> enum dma_data_direction direction);
> +#define ARCH_HAS_DMA_MMAP_COHERENT
> +extern int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
> + void *cpu_addr, dma_addr_t handle, size_t size);
> #endif /* _ASM_DMA_MAPPING_H */
> diff --git a/arch/mips/mm/dma-default.c b/arch/mips/mm/dma-default.c
> index 9547bc0..8388428 100644
> --- a/arch/mips/mm/dma-default.c
> +++ b/arch/mips/mm/dma-default.c
> @@ -375,3 +375,16 @@ void dma_cache_sync(struct device *dev, void *vaddr,
> size_t size,
> +int __weak dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma,
> + void *cpu_addr, dma_addr_t handle, size_t size)
> + struct page *pg;
> + vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);
> + cpu_addr = (void *)dma_addr_to_virt(dev, handle);
> + pg = virt_to_page(cpu_addr);
> + return remap_pfn_range(vma, vma->vm_start,
> + page_to_pfn(pg) + vma->vm_pgoff,
> + size, vma->vm_page_prot);