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 <a...@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.
