Re: [PATCH 25/67] dma-direct: rename dma_noop to dma_direct

[Vladimir Murzin <vladimir.murzin@arm.com>]

On 29/12/17 08:18, Christoph Hellwig wrote:
> The trivial direct mapping implementation already does a virtual to
> physical translation which isn't strictly a noop, and will soon learn
> to do non-direct but linear physical to dma translations through the
> device offset and a few small tricks.  Rename it to a better fitting
> name.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  MAINTAINERS                        |  2 +-
>  arch/arm/Kconfig                   |  2 +-
>  arch/arm/include/asm/dma-mapping.h |  2 +-
>  arch/arm/mm/dma-mapping-nommu.c    |  8 ++++----
>  arch/m32r/Kconfig                  |  2 +-
>  arch/riscv/Kconfig                 |  2 +-
>  arch/s390/Kconfig                  |  2 +-
>  include/asm-generic/dma-mapping.h  |  2 +-
>  include/linux/dma-mapping.h        |  2 +-
>  lib/Kconfig                        |  2 +-
>  lib/Makefile                       |  2 +-
>  lib/{dma-noop.c => dma-direct.c}   | 35 +++++++++++++++--------------------
>  12 files changed, 29 insertions(+), 34 deletions(-)
>  rename lib/{dma-noop.c => dma-direct.c} (53%)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index a8b35d9f41b2..b4005fe06e4c 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -4336,7 +4336,7 @@ T:	git git://git.infradead.org/users/hch/dma-mapping.git
>  W:	http://git.infradead.org/users/hch/dma-mapping.git
>  S:	Supported
>  F:	lib/dma-debug.c
> -F:	lib/dma-noop.c
> +F:	lib/dma-direct.c
>  F:	lib/dma-virt.c
>  F:	drivers/base/dma-mapping.c
>  F:	drivers/base/dma-coherent.c
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index 00d889a37965..430a0aa710d6 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -25,7 +25,7 @@ config ARM
>  	select CLONE_BACKWARDS
>  	select CPU_PM if (SUSPEND || CPU_IDLE)
>  	select DCACHE_WORD_ACCESS if HAVE_EFFICIENT_UNALIGNED_ACCESS
> -	select DMA_NOOP_OPS if !MMU
> +	select DMA_DIRECT_OPS if !MMU
>  	select EDAC_SUPPORT
>  	select EDAC_ATOMIC_SCRUB
>  	select GENERIC_ALLOCATOR
> diff --git a/arch/arm/include/asm/dma-mapping.h b/arch/arm/include/asm/dma-mapping.h
> index e5d9020c9ee1..8436f6ade57d 100644
> --- a/arch/arm/include/asm/dma-mapping.h
> +++ b/arch/arm/include/asm/dma-mapping.h
> @@ -18,7 +18,7 @@ extern const struct dma_map_ops arm_coherent_dma_ops;
>  
>  static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
>  {
> -	return IS_ENABLED(CONFIG_MMU) ? &arm_dma_ops : &dma_noop_ops;
> +	return IS_ENABLED(CONFIG_MMU) ? &arm_dma_ops : &dma_direct_ops;
>  }
>  
>  #ifdef __arch_page_to_dma
> diff --git a/arch/arm/mm/dma-mapping-nommu.c b/arch/arm/mm/dma-mapping-nommu.c
> index 1cced700e45a..49e9831dc0f1 100644
> --- a/arch/arm/mm/dma-mapping-nommu.c
> +++ b/arch/arm/mm/dma-mapping-nommu.c
> @@ -22,7 +22,7 @@
>  #include "dma.h"
>  
>  /*
> - *  dma_noop_ops is used if
> + *  dma_direct_ops is used if
>   *   - MMU/MPU is off
>   *   - cpu is v7m w/o cache support
>   *   - device is coherent
> @@ -39,7 +39,7 @@ static void *arm_nommu_dma_alloc(struct device *dev, size_t size,
>  				 unsigned long attrs)
>  
>  {
> -	const struct dma_map_ops *ops = &dma_noop_ops;
> +	const struct dma_map_ops *ops = &dma_direct_ops;
>  	void *ret;
>  
>  	/*
> @@ -70,7 +70,7 @@ static void arm_nommu_dma_free(struct device *dev, size_t size,
>  			       void *cpu_addr, dma_addr_t dma_addr,
>  			       unsigned long attrs)
>  {
> -	const struct dma_map_ops *ops = &dma_noop_ops;
> +	const struct dma_map_ops *ops = &dma_direct_ops;
>  
>  	if (attrs & DMA_ATTR_NON_CONSISTENT) {
>  		ops->free(dev, size, cpu_addr, dma_addr, attrs);
> @@ -214,7 +214,7 @@ EXPORT_SYMBOL(arm_nommu_dma_ops);
>  
>  static const struct dma_map_ops *arm_nommu_get_dma_map_ops(bool coherent)
>  {
> -	return coherent ? &dma_noop_ops : &arm_nommu_dma_ops;
> +	return coherent ? &dma_direct_ops : &arm_nommu_dma_ops;
>  }
>  
>  void arch_setup_dma_ops(struct device *dev, u64 dma_base, u64 size,
> diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
> index 498398d915c1..dd84ee194579 100644
> --- a/arch/m32r/Kconfig
> +++ b/arch/m32r/Kconfig
> @@ -19,7 +19,7 @@ config M32R
>  	select MODULES_USE_ELF_RELA
>  	select HAVE_DEBUG_STACKOVERFLOW
>  	select CPU_NO_EFFICIENT_FFS
> -	select DMA_NOOP_OPS
> +	select DMA_DIRECT_OPS
>  	select ARCH_NO_COHERENT_DMA_MMAP if !MMU
>  
>  config SBUS
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 2c6adf12713a..865e14f50c14 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -83,7 +83,7 @@ config PGTABLE_LEVELS
>  config HAVE_KPROBES
>  	def_bool n
>  
> -config DMA_NOOP_OPS
> +config DMA_DIRECT_OPS
>  	def_bool y
>  
>  menu "Platform type"
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index 829c67986db7..9376637229c9 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -140,7 +140,7 @@ config S390
>  	select HAVE_DEBUG_KMEMLEAK
>  	select HAVE_DMA_API_DEBUG
>  	select HAVE_DMA_CONTIGUOUS
> -	select DMA_NOOP_OPS
> +	select DMA_DIRECT_OPS
>  	select HAVE_DYNAMIC_FTRACE
>  	select HAVE_DYNAMIC_FTRACE_WITH_REGS
>  	select HAVE_EFFICIENT_UNALIGNED_ACCESS
> diff --git a/include/asm-generic/dma-mapping.h b/include/asm-generic/dma-mapping.h
> index 164031531d85..880a292d792f 100644
> --- a/include/asm-generic/dma-mapping.h
> +++ b/include/asm-generic/dma-mapping.h
> @@ -4,7 +4,7 @@
>  
>  static inline const struct dma_map_ops *get_arch_dma_ops(struct bus_type *bus)
>  {
> -	return &dma_noop_ops;
> +	return &dma_direct_ops;
>  }
>  
>  #endif /* _ASM_GENERIC_DMA_MAPPING_H */
> diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h
> index 72568bf4fc12..ff3528de5322 100644
> --- a/include/linux/dma-mapping.h
> +++ b/include/linux/dma-mapping.h
> @@ -143,7 +143,7 @@ struct dma_map_ops {
>  	bool is_phys;
>  };
>  
> -extern const struct dma_map_ops dma_noop_ops;
> +extern const struct dma_map_ops dma_direct_ops;
>  extern const struct dma_map_ops dma_virt_ops;
>  
>  #define DMA_BIT_MASK(n)	(((n) == 64) ? ~0ULL : ((1ULL<<(n))-1))
> diff --git a/lib/Kconfig b/lib/Kconfig
> index c5e84fbcb30b..9d3d649c9dc9 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -409,7 +409,7 @@ config HAS_DMA
>  	depends on !NO_DMA
>  	default y
>  
> -config DMA_NOOP_OPS
> +config DMA_DIRECT_OPS
>  	bool
>  	depends on HAS_DMA && (!64BIT || ARCH_DMA_ADDR_T_64BIT)
>  	default n
> diff --git a/lib/Makefile b/lib/Makefile
> index d11c48ec8ffd..749851abe85a 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -28,7 +28,7 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
>  
>  lib-$(CONFIG_MMU) += ioremap.o
>  lib-$(CONFIG_SMP) += cpumask.o
> -lib-$(CONFIG_DMA_NOOP_OPS) += dma-noop.o
> +lib-$(CONFIG_DMA_DIRECT_OPS) += dma-direct.o
>  lib-$(CONFIG_DMA_VIRT_OPS) += dma-virt.o
>  
>  lib-y	+= kobject.o klist.o
> diff --git a/lib/dma-noop.c b/lib/dma-direct.c
> similarity index 53%
> rename from lib/dma-noop.c
> rename to lib/dma-direct.c
> index c3728a0551f5..439db40854b7 100644
> --- a/lib/dma-noop.c
> +++ b/lib/dma-direct.c
> @@ -10,9 +10,8 @@
>  #include <linux/scatterlist.h>
>  #include <linux/pfn.h>
>  
> -static void *dma_noop_alloc(struct device *dev, size_t size,
> -			    dma_addr_t *dma_handle, gfp_t gfp,
> -			    unsigned long attrs)
> +static void *dma_direct_alloc(struct device *dev, size_t size,
> +		dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
>  {
>  	void *ret;
>  
> @@ -23,24 +22,21 @@ static void *dma_noop_alloc(struct device *dev, size_t size,
>  	return ret;
>  }
>  
> -static void dma_noop_free(struct device *dev, size_t size,
> -			  void *cpu_addr, dma_addr_t dma_addr,
> -			  unsigned long attrs)
> +static void dma_direct_free(struct device *dev, size_t size, void *cpu_addr,
> +		dma_addr_t dma_addr, unsigned long attrs)
>  {
>  	free_pages((unsigned long)cpu_addr, get_order(size));
>  }
>  
> -static dma_addr_t dma_noop_map_page(struct device *dev, struct page *page,
> -				      unsigned long offset, size_t size,
> -				      enum dma_data_direction dir,
> -				      unsigned long attrs)
> +static dma_addr_t dma_direct_map_page(struct device *dev, struct page *page,
> +		unsigned long offset, size_t size, enum dma_data_direction dir,
> +		unsigned long attrs)
>  {
>  	return page_to_phys(page) + offset - PFN_PHYS(dev->dma_pfn_offset);
>  }
>  
> -static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
> -			     enum dma_data_direction dir,
> -			     unsigned long attrs)
> +static int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl,
> +		int nents, enum dma_data_direction dir, unsigned long attrs)
>  {
>  	int i;
>  	struct scatterlist *sg;
> @@ -58,12 +54,11 @@ static int dma_noop_map_sg(struct device *dev, struct scatterlist *sgl, int nent
>  	return nents;
>  }
>  
> -const struct dma_map_ops dma_noop_ops = {
> -	.alloc			= dma_noop_alloc,
> -	.free			= dma_noop_free,
> -	.map_page		= dma_noop_map_page,
> -	.map_sg			= dma_noop_map_sg,
> +const struct dma_map_ops dma_direct_ops = {
> +	.alloc			= dma_direct_alloc,
> +	.free			= dma_direct_free,
> +	.map_page		= dma_direct_map_page,
> +	.map_sg			= dma_direct_map_sg,
>  	.is_phys		= true,
>  };
> -
> -EXPORT_SYMBOL(dma_noop_ops);
> +EXPORT_SYMBOL(dma_direct_ops);
> 

From ARM NOMMU perspective

Reviewed-by: Vladimir Murzin <vladimir.murzin@arm.com>

Thanks
Vladimir