Messages in this thread | | | Subject | Re: [PATCH kernel v3 1/2] dma: Allow mixing bypass and mapped DMA operation | From | Alexey Kardashevskiy <> | Date | Thu, 29 Oct 2020 10:15:13 +1100 |
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On 29/10/2020 04:22, Christoph Hellwig wrote: > On Wed, Oct 28, 2020 at 06:00:29PM +1100, Alexey Kardashevskiy wrote: >> At the moment we allow bypassing DMA ops only when we can do this for >> the entire RAM. However there are configs with mixed type memory >> where we could still allow bypassing IOMMU in most cases; >> POWERPC with persistent memory is one example. >> >> This adds an arch hook to determine where bypass can still work and >> we invoke direct DMA API. The following patch checks the bus limit >> on POWERPC to allow or disallow direct mapping. >> >> This adds a CONFIG_ARCH_HAS_DMA_SET_MASK config option to make arch_xxxx >> hooks no-op by default. >> >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> >> --- >> kernel/dma/mapping.c | 24 ++++++++++++++++++++---- >> kernel/dma/Kconfig | 4 ++++ >> 2 files changed, 24 insertions(+), 4 deletions(-) >> >> diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c >> index 51bb8fa8eb89..a0bc9eb876ed 100644 >> --- a/kernel/dma/mapping.c >> +++ b/kernel/dma/mapping.c >> @@ -137,6 +137,18 @@ static inline bool dma_map_direct(struct device *dev, >> return dma_go_direct(dev, *dev->dma_mask, ops); >> } >> >> +#ifdef CONFIG_ARCH_HAS_DMA_MAP_DIRECT >> +bool arch_dma_map_page_direct(struct device *dev, phys_addr_t addr); >> +bool arch_dma_unmap_page_direct(struct device *dev, dma_addr_t dma_handle); >> +bool arch_dma_map_sg_direct(struct device *dev, struct scatterlist *sg, int nents); >> +bool arch_dma_unmap_sg_direct(struct device *dev, struct scatterlist *sg, int nents); >> +#else >> +#define arch_dma_map_page_direct(d, a) (0) >> +#define arch_dma_unmap_page_direct(d, a) (0) >> +#define arch_dma_map_sg_direct(d, s, n) (0) >> +#define arch_dma_unmap_sg_direct(d, s, n) (0) >> +#endif > > A bunch of overly long lines here. Except for that this looks ok to me. > If you want me to queue up the series I can just fix it up.
I thought 100 is the new limit since https://lkml.org/lkml/2020/5/29/1038 (yeah that mentioned some Christoph :) ) and having these multiline does not make a huge difference but feel free fixing them up.
Are you going to take both patches? Do you need mpe's ack? Thanks,
-- Alexey
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