| Message ID | 20190826132553.4116-4-hch@lst.de (mailing list archive) |
|---|---|
| State | Mainlined |
| Commit | 419e2f1838819e954071dfa1d1f820ab3386ada1 |
| Headers | show |
| Series | [1/6] unicore32: remove the unused pgprot_dmacoherent define | expand |
Hi Christoph, On Mon, Aug 26, 2019 at 03:25:50PM +0200, Christoph Hellwig wrote: > arch_dma_mmap_pgprot is used for two things: > > 1) to override the "normal" uncached page attributes for mapping > memory coherent to devices that can't snoop the CPU caches > 2) to provide the special DMA_ATTR_WRITE_COMBINE semantics on older > arm systems and some mips platforms > > Replace one with the pgprot_dmacoherent macro that is already provided > by arm and much simpler to use, and lift the DMA_ATTR_WRITE_COMBINE > handling to common code with an explicit arch opt-in. > > Signed-off-by: Christoph Hellwig <hch@lst.de> > Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> For the MIPS bits: Acked-by: Paul Burton <paul.burton@mips.com> Thanks, Paul > --- > arch/arm/Kconfig | 2 +- > arch/arm/mm/dma-mapping.c | 6 ------ > arch/arm64/Kconfig | 1 - > arch/arm64/include/asm/pgtable.h | 4 ++++ > arch/arm64/mm/dma-mapping.c | 6 ------ > arch/m68k/Kconfig | 1 - > arch/m68k/include/asm/pgtable_mm.h | 3 +++ > arch/m68k/kernel/dma.c | 3 +-- > arch/mips/Kconfig | 2 +- > arch/mips/mm/dma-noncoherent.c | 8 -------- > include/linux/dma-noncoherent.h | 13 +++++++++++-- > kernel/dma/Kconfig | 12 +++++++++--- > kernel/dma/mapping.c | 8 +++++--- > 13 files changed, 35 insertions(+), 34 deletions(-) > > diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig > index 24360211534a..217083caeabd 100644 > --- a/arch/arm/Kconfig > +++ b/arch/arm/Kconfig > @@ -8,7 +8,7 @@ config ARM > select ARCH_HAS_DEBUG_VIRTUAL if MMU > select ARCH_HAS_DEVMEM_IS_ALLOWED > select ARCH_HAS_DMA_COHERENT_TO_PFN if SWIOTLB > - select ARCH_HAS_DMA_MMAP_PGPROT if SWIOTLB > + select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE > select ARCH_HAS_ELF_RANDOMIZE > select ARCH_HAS_FORTIFY_SOURCE > select ARCH_HAS_KEEPINITRD > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index d42557ee69c2..d27b12f61737 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -2402,12 +2402,6 @@ long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr, > return dma_to_pfn(dev, dma_addr); > } > > -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, > - unsigned long attrs) > -{ > - return __get_dma_pgprot(attrs, prot); > -} > - > void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, > gfp_t gfp, unsigned long attrs) > { > diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig > index 3adcec05b1f6..dab9dda34206 100644 > --- a/arch/arm64/Kconfig > +++ b/arch/arm64/Kconfig > @@ -13,7 +13,6 @@ config ARM64 > select ARCH_HAS_DEBUG_VIRTUAL > select ARCH_HAS_DEVMEM_IS_ALLOWED > select ARCH_HAS_DMA_COHERENT_TO_PFN > - select ARCH_HAS_DMA_MMAP_PGPROT > select ARCH_HAS_DMA_PREP_COHERENT > select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI > select ARCH_HAS_ELF_RANDOMIZE > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index e09760ece844..6700371227d1 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -435,6 +435,10 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd) > __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN) > #define pgprot_device(prot) \ > __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRE) | PTE_PXN | PTE_UXN) > +#define pgprot_dmacoherent(prot) \ > + __pgprot_modify(prot, PTE_ATTRINDX_MASK, \ > + PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN) > + > #define __HAVE_PHYS_MEM_ACCESS_PROT > struct file; > extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, > diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c > index bd2b039f43a6..676efcda51e6 100644 > --- a/arch/arm64/mm/dma-mapping.c > +++ b/arch/arm64/mm/dma-mapping.c > @@ -11,12 +11,6 @@ > > #include <asm/cacheflush.h> > > -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, > - unsigned long attrs) > -{ > - return pgprot_writecombine(prot); > -} > - > void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr, > size_t size, enum dma_data_direction dir) > { > diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig > index c518d695c376..a9e564306d3e 100644 > --- a/arch/m68k/Kconfig > +++ b/arch/m68k/Kconfig > @@ -4,7 +4,6 @@ config M68K > default y > select ARCH_32BIT_OFF_T > select ARCH_HAS_BINFMT_FLAT > - select ARCH_HAS_DMA_MMAP_PGPROT if MMU && !COLDFIRE > select ARCH_HAS_DMA_PREP_COHERENT if HAS_DMA && MMU && !COLDFIRE > select ARCH_HAS_SYNC_DMA_FOR_DEVICE if HAS_DMA > select ARCH_MIGHT_HAVE_PC_PARPORT if ISA > diff --git a/arch/m68k/include/asm/pgtable_mm.h b/arch/m68k/include/asm/pgtable_mm.h > index fe3ddd73a0cc..fde4534b974f 100644 > --- a/arch/m68k/include/asm/pgtable_mm.h > +++ b/arch/m68k/include/asm/pgtable_mm.h > @@ -169,6 +169,9 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, > ? (__pgprot((pgprot_val(prot) & _CACHEMASK040) | _PAGE_NOCACHE_S)) \ > : (prot))) > > +pgprot_t pgprot_dmacoherent(pgprot_t prot); > +#define pgprot_dmacoherent(prot) pgprot_dmacoherent(prot) > + > #endif /* CONFIG_COLDFIRE */ > #include <asm-generic/pgtable.h> > #endif /* !__ASSEMBLY__ */ > diff --git a/arch/m68k/kernel/dma.c b/arch/m68k/kernel/dma.c > index 30cd59caf037..35064150e348 100644 > --- a/arch/m68k/kernel/dma.c > +++ b/arch/m68k/kernel/dma.c > @@ -23,8 +23,7 @@ void arch_dma_prep_coherent(struct page *page, size_t size) > cache_push(page_to_phys(page), size); > } > > -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, > - unsigned long attrs) > +pgprot_t pgprot_dmacoherent(pgprot_t prot) > { > if (CPU_IS_040_OR_060) { > pgprot_val(prot) &= ~_PAGE_CACHE040; > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig > index d50fafd7bf3a..fc88f68ea1ee 100644 > --- a/arch/mips/Kconfig > +++ b/arch/mips/Kconfig > @@ -1119,7 +1119,7 @@ config DMA_PERDEV_COHERENT > > config DMA_NONCOHERENT > bool > - select ARCH_HAS_DMA_MMAP_PGPROT > + select ARCH_HAS_DMA_WRITE_COMBINE > select ARCH_HAS_SYNC_DMA_FOR_DEVICE > select ARCH_HAS_UNCACHED_SEGMENT > select NEED_DMA_MAP_STATE > diff --git a/arch/mips/mm/dma-noncoherent.c b/arch/mips/mm/dma-noncoherent.c > index ed56c6fa7be2..1d4d57dd9acf 100644 > --- a/arch/mips/mm/dma-noncoherent.c > +++ b/arch/mips/mm/dma-noncoherent.c > @@ -65,14 +65,6 @@ long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr, > return page_to_pfn(virt_to_page(cached_kernel_address(cpu_addr))); > } > > -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, > - unsigned long attrs) > -{ > - if (attrs & DMA_ATTR_WRITE_COMBINE) > - return pgprot_writecombine(prot); > - return pgprot_noncached(prot); > -} > - > static inline void dma_sync_virt(void *addr, size_t size, > enum dma_data_direction dir) > { > diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h > index 0bff3d7fac92..dd3de6d88fc0 100644 > --- a/include/linux/dma-noncoherent.h > +++ b/include/linux/dma-noncoherent.h > @@ -3,6 +3,7 @@ > #define _LINUX_DMA_NONCOHERENT_H 1 > > #include <linux/dma-mapping.h> > +#include <asm/pgtable.h> > > #ifdef CONFIG_ARCH_HAS_DMA_COHERENCE_H > #include <asm/dma-coherence.h> > @@ -42,10 +43,18 @@ void arch_dma_free(struct device *dev, size_t size, void *cpu_addr, > dma_addr_t dma_addr, unsigned long attrs); > long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr, > dma_addr_t dma_addr); > -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, > - unsigned long attrs); > > #ifdef CONFIG_MMU > +/* > + * Page protection so that devices that can't snoop CPU caches can use the > + * memory coherently. We default to pgprot_noncached which is usually used > + * for ioremap as a safe bet, but architectures can override this with less > + * strict semantics if possible. > + */ > +#ifndef pgprot_dmacoherent > +#define pgprot_dmacoherent(prot) pgprot_noncached(prot) > +#endif > + > pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs); > #else > static inline pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, > diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig > index 9decbba255fc..73c5c2b8e824 100644 > --- a/kernel/dma/Kconfig > +++ b/kernel/dma/Kconfig > @@ -20,6 +20,15 @@ config ARCH_HAS_DMA_COHERENCE_H > config ARCH_HAS_DMA_SET_MASK > bool > > +# > +# Select this option if the architecture needs special handling for > +# DMA_ATTR_WRITE_COMBINE. Normally the "uncached" mapping should be what > +# people thing of when saying write combine, so very few platforms should > +# need to enable this. > +# > +config ARCH_HAS_DMA_WRITE_COMBINE > + bool > + > config DMA_DECLARE_COHERENT > bool > > @@ -45,9 +54,6 @@ config ARCH_HAS_DMA_PREP_COHERENT > config ARCH_HAS_DMA_COHERENT_TO_PFN > bool > > -config ARCH_HAS_DMA_MMAP_PGPROT > - bool > - > config ARCH_HAS_FORCE_DMA_UNENCRYPTED > bool > > diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c > index b0038ca3aa92..1b96616c9f20 100644 > --- a/kernel/dma/mapping.c > +++ b/kernel/dma/mapping.c > @@ -161,9 +161,11 @@ pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs) > (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) && > (attrs & DMA_ATTR_NON_CONSISTENT))) > return prot; > - if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_MMAP_PGPROT)) > - return arch_dma_mmap_pgprot(dev, prot, attrs); > - return pgprot_noncached(prot); > +#ifdef CONFIG_ARCH_HAS_DMA_WRITE_COMBINE > + if (attrs & DMA_ATTR_WRITE_COMBINE) > + return pgprot_writecombine(prot); > +#endif > + return pgprot_dmacoherent(prot); > } > #endif /* CONFIG_MMU */ > > -- > 2.20.1 >
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 24360211534a..217083caeabd 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig @@ -8,7 +8,7 @@ config ARM select ARCH_HAS_DEBUG_VIRTUAL if MMU select ARCH_HAS_DEVMEM_IS_ALLOWED select ARCH_HAS_DMA_COHERENT_TO_PFN if SWIOTLB - select ARCH_HAS_DMA_MMAP_PGPROT if SWIOTLB + select ARCH_HAS_DMA_WRITE_COMBINE if !ARM_DMA_MEM_BUFFERABLE select ARCH_HAS_ELF_RANDOMIZE select ARCH_HAS_FORTIFY_SOURCE select ARCH_HAS_KEEPINITRD diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index d42557ee69c2..d27b12f61737 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -2402,12 +2402,6 @@ long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr, return dma_to_pfn(dev, dma_addr); } -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, - unsigned long attrs) -{ - return __get_dma_pgprot(attrs, prot); -} - void *arch_dma_alloc(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) { diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 3adcec05b1f6..dab9dda34206 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -13,7 +13,6 @@ config ARM64 select ARCH_HAS_DEBUG_VIRTUAL select ARCH_HAS_DEVMEM_IS_ALLOWED select ARCH_HAS_DMA_COHERENT_TO_PFN - select ARCH_HAS_DMA_MMAP_PGPROT select ARCH_HAS_DMA_PREP_COHERENT select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI select ARCH_HAS_ELF_RANDOMIZE diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index e09760ece844..6700371227d1 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -435,6 +435,10 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd) __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN) #define pgprot_device(prot) \ __pgprot_modify(prot, PTE_ATTRINDX_MASK, PTE_ATTRINDX(MT_DEVICE_nGnRE) | PTE_PXN | PTE_UXN) +#define pgprot_dmacoherent(prot) \ + __pgprot_modify(prot, PTE_ATTRINDX_MASK, \ + PTE_ATTRINDX(MT_NORMAL_NC) | PTE_PXN | PTE_UXN) + #define __HAVE_PHYS_MEM_ACCESS_PROT struct file; extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, diff --git a/arch/arm64/mm/dma-mapping.c b/arch/arm64/mm/dma-mapping.c index bd2b039f43a6..676efcda51e6 100644 --- a/arch/arm64/mm/dma-mapping.c +++ b/arch/arm64/mm/dma-mapping.c @@ -11,12 +11,6 @@ #include <asm/cacheflush.h> -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, - unsigned long attrs) -{ - return pgprot_writecombine(prot); -} - void arch_sync_dma_for_device(struct device *dev, phys_addr_t paddr, size_t size, enum dma_data_direction dir) { diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig index c518d695c376..a9e564306d3e 100644 --- a/arch/m68k/Kconfig +++ b/arch/m68k/Kconfig @@ -4,7 +4,6 @@ config M68K default y select ARCH_32BIT_OFF_T select ARCH_HAS_BINFMT_FLAT - select ARCH_HAS_DMA_MMAP_PGPROT if MMU && !COLDFIRE select ARCH_HAS_DMA_PREP_COHERENT if HAS_DMA && MMU && !COLDFIRE select ARCH_HAS_SYNC_DMA_FOR_DEVICE if HAS_DMA select ARCH_MIGHT_HAVE_PC_PARPORT if ISA diff --git a/arch/m68k/include/asm/pgtable_mm.h b/arch/m68k/include/asm/pgtable_mm.h index fe3ddd73a0cc..fde4534b974f 100644 --- a/arch/m68k/include/asm/pgtable_mm.h +++ b/arch/m68k/include/asm/pgtable_mm.h @@ -169,6 +169,9 @@ static inline void update_mmu_cache(struct vm_area_struct *vma, ? (__pgprot((pgprot_val(prot) & _CACHEMASK040) | _PAGE_NOCACHE_S)) \ : (prot))) +pgprot_t pgprot_dmacoherent(pgprot_t prot); +#define pgprot_dmacoherent(prot) pgprot_dmacoherent(prot) + #endif /* CONFIG_COLDFIRE */ #include <asm-generic/pgtable.h> #endif /* !__ASSEMBLY__ */ diff --git a/arch/m68k/kernel/dma.c b/arch/m68k/kernel/dma.c index 30cd59caf037..35064150e348 100644 --- a/arch/m68k/kernel/dma.c +++ b/arch/m68k/kernel/dma.c @@ -23,8 +23,7 @@ void arch_dma_prep_coherent(struct page *page, size_t size) cache_push(page_to_phys(page), size); } -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, - unsigned long attrs) +pgprot_t pgprot_dmacoherent(pgprot_t prot) { if (CPU_IS_040_OR_060) { pgprot_val(prot) &= ~_PAGE_CACHE040; diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig index d50fafd7bf3a..fc88f68ea1ee 100644 --- a/arch/mips/Kconfig +++ b/arch/mips/Kconfig @@ -1119,7 +1119,7 @@ config DMA_PERDEV_COHERENT config DMA_NONCOHERENT bool - select ARCH_HAS_DMA_MMAP_PGPROT + select ARCH_HAS_DMA_WRITE_COMBINE select ARCH_HAS_SYNC_DMA_FOR_DEVICE select ARCH_HAS_UNCACHED_SEGMENT select NEED_DMA_MAP_STATE diff --git a/arch/mips/mm/dma-noncoherent.c b/arch/mips/mm/dma-noncoherent.c index ed56c6fa7be2..1d4d57dd9acf 100644 --- a/arch/mips/mm/dma-noncoherent.c +++ b/arch/mips/mm/dma-noncoherent.c @@ -65,14 +65,6 @@ long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr, return page_to_pfn(virt_to_page(cached_kernel_address(cpu_addr))); } -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, - unsigned long attrs) -{ - if (attrs & DMA_ATTR_WRITE_COMBINE) - return pgprot_writecombine(prot); - return pgprot_noncached(prot); -} - static inline void dma_sync_virt(void *addr, size_t size, enum dma_data_direction dir) { diff --git a/include/linux/dma-noncoherent.h b/include/linux/dma-noncoherent.h index 0bff3d7fac92..dd3de6d88fc0 100644 --- a/include/linux/dma-noncoherent.h +++ b/include/linux/dma-noncoherent.h @@ -3,6 +3,7 @@ #define _LINUX_DMA_NONCOHERENT_H 1 #include <linux/dma-mapping.h> +#include <asm/pgtable.h> #ifdef CONFIG_ARCH_HAS_DMA_COHERENCE_H #include <asm/dma-coherence.h> @@ -42,10 +43,18 @@ void arch_dma_free(struct device *dev, size_t size, void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs); long arch_dma_coherent_to_pfn(struct device *dev, void *cpu_addr, dma_addr_t dma_addr); -pgprot_t arch_dma_mmap_pgprot(struct device *dev, pgprot_t prot, - unsigned long attrs); #ifdef CONFIG_MMU +/* + * Page protection so that devices that can't snoop CPU caches can use the + * memory coherently. We default to pgprot_noncached which is usually used + * for ioremap as a safe bet, but architectures can override this with less + * strict semantics if possible. + */ +#ifndef pgprot_dmacoherent +#define pgprot_dmacoherent(prot) pgprot_noncached(prot) +#endif + pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs); #else static inline pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, diff --git a/kernel/dma/Kconfig b/kernel/dma/Kconfig index 9decbba255fc..73c5c2b8e824 100644 --- a/kernel/dma/Kconfig +++ b/kernel/dma/Kconfig @@ -20,6 +20,15 @@ config ARCH_HAS_DMA_COHERENCE_H config ARCH_HAS_DMA_SET_MASK bool +# +# Select this option if the architecture needs special handling for +# DMA_ATTR_WRITE_COMBINE. Normally the "uncached" mapping should be what +# people thing of when saying write combine, so very few platforms should +# need to enable this. +# +config ARCH_HAS_DMA_WRITE_COMBINE + bool + config DMA_DECLARE_COHERENT bool @@ -45,9 +54,6 @@ config ARCH_HAS_DMA_PREP_COHERENT config ARCH_HAS_DMA_COHERENT_TO_PFN bool -config ARCH_HAS_DMA_MMAP_PGPROT - bool - config ARCH_HAS_FORCE_DMA_UNENCRYPTED bool diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index b0038ca3aa92..1b96616c9f20 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -161,9 +161,11 @@ pgprot_t dma_pgprot(struct device *dev, pgprot_t prot, unsigned long attrs) (IS_ENABLED(CONFIG_DMA_NONCOHERENT_CACHE_SYNC) && (attrs & DMA_ATTR_NON_CONSISTENT))) return prot; - if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_MMAP_PGPROT)) - return arch_dma_mmap_pgprot(dev, prot, attrs); - return pgprot_noncached(prot); +#ifdef CONFIG_ARCH_HAS_DMA_WRITE_COMBINE + if (attrs & DMA_ATTR_WRITE_COMBINE) + return pgprot_writecombine(prot); +#endif + return pgprot_dmacoherent(prot); } #endif /* CONFIG_MMU */
arch_dma_mmap_pgprot is used for two things: 1) to override the "normal" uncached page attributes for mapping memory coherent to devices that can't snoop the CPU caches 2) to provide the special DMA_ATTR_WRITE_COMBINE semantics on older arm systems and some mips platforms Replace one with the pgprot_dmacoherent macro that is already provided by arm and much simpler to use, and lift the DMA_ATTR_WRITE_COMBINE handling to common code with an explicit arch opt-in. Signed-off-by: Christoph Hellwig <hch@lst.de> Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> --- arch/arm/Kconfig | 2 +- arch/arm/mm/dma-mapping.c | 6 ------ arch/arm64/Kconfig | 1 - arch/arm64/include/asm/pgtable.h | 4 ++++ arch/arm64/mm/dma-mapping.c | 6 ------ arch/m68k/Kconfig | 1 - arch/m68k/include/asm/pgtable_mm.h | 3 +++ arch/m68k/kernel/dma.c | 3 +-- arch/mips/Kconfig | 2 +- arch/mips/mm/dma-noncoherent.c | 8 -------- include/linux/dma-noncoherent.h | 13 +++++++++++-- kernel/dma/Kconfig | 12 +++++++++--- kernel/dma/mapping.c | 8 +++++--- 13 files changed, 35 insertions(+), 34 deletions(-)