Re: [PATCH 6/7] dma-mapping: make the global coherent pool conditional

[Atish Patra <atishp@atishpatra.org>]

On Sun, Jul 11, 2021 at 11:25 PM Christoph Hellwig <hch@lst.de> wrote:
>
> Only build the code to support the global coherent pool if support for
> it is enabled.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> Tested-by: Dillon Min <dillon.minfei@gmail.com>
> ---
>  include/linux/dma-map-ops.h | 18 +++++++-------
>  kernel/dma/coherent.c       | 47 ++++++++++++++++++++-----------------
>  2 files changed, 35 insertions(+), 30 deletions(-)
>
> diff --git a/include/linux/dma-map-ops.h b/include/linux/dma-map-ops.h
> index 7e49bb86a0c0..9b79aa4dd300 100644
> --- a/include/linux/dma-map-ops.h
> +++ b/include/linux/dma-map-ops.h
> @@ -170,13 +170,6 @@ int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
>  int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr);
>  int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
>                 void *cpu_addr, size_t size, int *ret);
> -
> -void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
> -               dma_addr_t *dma_handle);
> -int dma_release_from_global_coherent(int order, void *vaddr);
> -int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *cpu_addr,
> -               size_t size, int *ret);
> -int dma_init_global_coherent(phys_addr_t phys_addr, size_t size);
>  #else
>  static inline int dma_declare_coherent_memory(struct device *dev,
>                 phys_addr_t phys_addr, dma_addr_t device_addr, size_t size)
> @@ -186,7 +179,16 @@ static inline int dma_declare_coherent_memory(struct device *dev,
>  #define dma_alloc_from_dev_coherent(dev, size, handle, ret) (0)
>  #define dma_release_from_dev_coherent(dev, order, vaddr) (0)
>  #define dma_mmap_from_dev_coherent(dev, vma, vaddr, order, ret) (0)
> +#endif /* CONFIG_DMA_DECLARE_COHERENT */
>
> +#ifdef CONFIG_DMA_GLOBAL_POOL
> +void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
> +               dma_addr_t *dma_handle);
> +int dma_release_from_global_coherent(int order, void *vaddr);
> +int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *cpu_addr,
> +               size_t size, int *ret);
> +int dma_init_global_coherent(phys_addr_t phys_addr, size_t size);
> +#else
>  static inline void *dma_alloc_from_global_coherent(struct device *dev,
>                 ssize_t size, dma_addr_t *dma_handle)
>  {
> @@ -201,7 +203,7 @@ static inline int dma_mmap_from_global_coherent(struct vm_area_struct *vma,
>  {
>         return 0;
>  }
> -#endif /* CONFIG_DMA_DECLARE_COHERENT */
> +#endif /* CONFIG_DMA_GLOBAL_POOL */
>
>  /*
>   * This is the actual return value from the ->alloc_noncontiguous method.
> diff --git a/kernel/dma/coherent.c b/kernel/dma/coherent.c
> index 160d4e246ecb..c05408902a68 100644
> --- a/kernel/dma/coherent.c
> +++ b/kernel/dma/coherent.c
> @@ -20,8 +20,6 @@ struct dma_coherent_mem {
>         bool            use_dev_dma_pfn_offset;
>  };
>
> -static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
> -
>  static inline struct dma_coherent_mem *dev_get_coherent_memory(struct device *dev)
>  {
>         if (dev && dev->dma_mem)
> @@ -191,16 +189,6 @@ int dma_alloc_from_dev_coherent(struct device *dev, ssize_t size,
>         return 1;
>  }
>
> -void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
> -                                    dma_addr_t *dma_handle)
> -{
> -       if (!dma_coherent_default_memory)
> -               return NULL;
> -
> -       return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size,
> -                                        dma_handle);
> -}
> -
>  static int __dma_release_from_coherent(struct dma_coherent_mem *mem,
>                                        int order, void *vaddr)
>  {
> @@ -236,15 +224,6 @@ int dma_release_from_dev_coherent(struct device *dev, int order, void *vaddr)
>         return __dma_release_from_coherent(mem, order, vaddr);
>  }
>
> -int dma_release_from_global_coherent(int order, void *vaddr)
> -{
> -       if (!dma_coherent_default_memory)
> -               return 0;
> -
> -       return __dma_release_from_coherent(dma_coherent_default_memory, order,
> -                       vaddr);
> -}
> -
>  static int __dma_mmap_from_coherent(struct dma_coherent_mem *mem,
>                 struct vm_area_struct *vma, void *vaddr, size_t size, int *ret)
>  {
> @@ -290,6 +269,28 @@ int dma_mmap_from_dev_coherent(struct device *dev, struct vm_area_struct *vma,
>         return __dma_mmap_from_coherent(mem, vma, vaddr, size, ret);
>  }
>
> +#ifdef CONFIG_DMA_GLOBAL_POOL
> +static struct dma_coherent_mem *dma_coherent_default_memory __ro_after_init;
> +
> +void *dma_alloc_from_global_coherent(struct device *dev, ssize_t size,
> +                                    dma_addr_t *dma_handle)
> +{
> +       if (!dma_coherent_default_memory)
> +               return NULL;
> +
> +       return __dma_alloc_from_coherent(dev, dma_coherent_default_memory, size,
> +                                        dma_handle);
> +}
> +
> +int dma_release_from_global_coherent(int order, void *vaddr)
> +{
> +       if (!dma_coherent_default_memory)
> +               return 0;
> +
> +       return __dma_release_from_coherent(dma_coherent_default_memory, order,
> +                       vaddr);
> +}
> +
>  int dma_mmap_from_global_coherent(struct vm_area_struct *vma, void *vaddr,
>                                    size_t size, int *ret)
>  {
> @@ -311,6 +312,7 @@ int dma_init_global_coherent(phys_addr_t phys_addr, size_t size)
>         pr_info("DMA: default coherent area is set\n");
>         return 0;
>  }
> +#endif /* CONFIG_DMA_GLOBAL_POOL */
>
>  /*
>   * Support for reserved memory regions defined in device tree
> @@ -377,6 +379,7 @@ static int __init rmem_dma_setup(struct reserved_mem *rmem)
>         return 0;
>  }
>
> +#ifdef CONFIG_DMA_GLOBAL_POOL
>  static int __init dma_init_reserved_memory(void)
>  {
>         if (!dma_reserved_default_memory)
> @@ -384,8 +387,8 @@ static int __init dma_init_reserved_memory(void)
>         return dma_init_global_coherent(dma_reserved_default_memory->base,
>                                         dma_reserved_default_memory->size);

dma_reserved_default_memory also needs to be moved inside
CONFIG_DMA_GLOBAL_POOL because
all the usages are already part of that config.


>  }
> -
>  core_initcall(dma_init_reserved_memory);
> +#endif /* CONFIG_DMA_GLOBAL_POOL */
>
>  RESERVEDMEM_OF_DECLARE(dma, "shared-dma-pool", rmem_dma_setup);
>  #endif
> --
> 2.30.2
>
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--
Regards,
Atish