Messages in this thread Patch in this message | | | Date | Thu, 23 Oct 2008 20:46:55 +0900 | Subject | Re: swiotlb_alloc_coherent: allocated memory is out of range for device | From | FUJITA Tomonori <> |
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On Thu, 23 Oct 2008 12:15:57 +0200 Ingo Molnar <mingo@elte.hu> wrote:
> > * Takashi Iwai <tiwai@suse.de> wrote: > > > At Thu, 23 Oct 2008 07:22:09 +0200, > > I wrote: > > > > > > > The current dma_alloc_coherent (asm-x86/dma-mapping.h) handles the gfp > > > > flags in the exact same way as the old dma_alloc_coherent > > > > (pci-dma.c). Neither sets GFP_DMA even if coherent_dma_mask is > > > > 24bits. The old code is fine because of the GFP_DMA retry > > > > mechanism. But if coherent_dma_mask is 24bits, there is no point to go > > > > into the GFP_DMA retry mechanism. We should use GFP_DMA in the first > > > > place. > > > > > > > > How about the following patch? > > > > > > I'll give it a try later (the machine is in my office). > > > > The patch seems working fine. Thanks! > > > > Tested-by: Takashi Iwai <tiwai@suse.de> > > thanks guys - i've queued it up in tip/core/urgent and will send a pull > request to Linus later today.
Thanks, I can't find the commit right now so I'm not sure if you need the patch description but anyway, here's a sane format of the patch.
= From: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Subject: [PATCH] x86: use GFP_DMA for 24bit coherent_dma_mask
dma_alloc_coherent (include/asm-x86/dma-mapping.h) avoids GFP_DMA allocation first and if the allocated address is not fit for the device's coherent_dma_mask, then dma_alloc_coherent does GFP_DMA allocation. This is because dma_alloc_coherent avoids precious GFP_DMA zone if possible. This is also how the old dma_alloc_coherent (arch/x86/kernel/pci-dma.c) works.
However, if the coherent_dma_mask of a device is 24bit, there is no point to go into the above GFP_DMA retry mechanism. We had better use GFP_DMA in the first place.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp> Tested-by: Takashi Iwai <tiwai@suse.de> --- include/asm-x86/dma-mapping.h | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-)
diff --git a/include/asm-x86/dma-mapping.h b/include/asm-x86/dma-mapping.h index 219c33d..05fcec5 100644 --- a/include/asm-x86/dma-mapping.h +++ b/include/asm-x86/dma-mapping.h @@ -255,9 +255,11 @@ static inline unsigned long dma_alloc_coherent_mask(struct device *dev, static inline gfp_t dma_alloc_coherent_gfp_flags(struct device *dev, gfp_t gfp) { -#ifdef CONFIG_X86_64 unsigned long dma_mask = dma_alloc_coherent_mask(dev, gfp); + if (dma_mask <= DMA_24BIT_MASK) + gfp |= GFP_DMA; +#ifdef CONFIG_X86_64 if (dma_mask <= DMA_32BIT_MASK && !(gfp & GFP_DMA)) gfp |= GFP_DMA32; #endif -- 1.5.5.GIT
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