Messages in this thread | | | Subject | Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift | From | Alexey Kardashevskiy <> | Date | Tue, 27 Oct 2015 17:02:16 +1100 |
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On 10/24/2015 07:57 AM, Nishanth Aravamudan wrote: > On Power, the kernel's page size can differ from the IOMMU's page size, > so we need to override the generic implementation, which always returns > the kernel's page size. Lookup the IOMMU's page size from struct > iommu_table, if available. Fallback to the kernel's page size, > otherwise. > > Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> > --- > arch/powerpc/include/asm/dma-mapping.h | 3 +++ > arch/powerpc/kernel/dma.c | 9 +++++++++ > 2 files changed, 12 insertions(+) > > diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h > index 7f522c0..c5638f4 100644 > --- a/arch/powerpc/include/asm/dma-mapping.h > +++ b/arch/powerpc/include/asm/dma-mapping.h > @@ -125,6 +125,9 @@ static inline void set_dma_offset(struct device *dev, dma_addr_t off) > #define HAVE_ARCH_DMA_SET_MASK 1 > extern int dma_set_mask(struct device *dev, u64 dma_mask); > > +#define HAVE_ARCH_DMA_GET_PAGE_SHIFT 1 > +extern unsigned long dma_get_page_shift(struct device *dev); > + > #include <asm-generic/dma-mapping-common.h> > > extern int __dma_set_mask(struct device *dev, u64 dma_mask); > diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c > index 59503ed..e805af2 100644 > --- a/arch/powerpc/kernel/dma.c > +++ b/arch/powerpc/kernel/dma.c > @@ -335,6 +335,15 @@ int dma_set_mask(struct device *dev, u64 dma_mask) > } > EXPORT_SYMBOL(dma_set_mask); > > +unsigned long dma_get_page_shift(struct device *dev) > +{ > + struct iommu_table *tbl = get_iommu_table_base(dev); > + if (tbl) > + return tbl->it_page_shift;
All PCI devices have this initialized on POWER (at least, our, IBM's POWER) so 4K will always be returned here while in the case of (get_dma_ops(dev)==&dma_direct_ops) it could actually return PAGE_SHIFT. Is 4K still preferred value to return here?
> + return PAGE_SHIFT; > +} > +EXPORT_SYMBOL(dma_get_page_shift); > + > u64 __dma_get_required_mask(struct device *dev) > { > struct dma_map_ops *dma_ops = get_dma_ops(dev); >
-- Alexey
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