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dma-direct: add support for dma_coherent_default_memory 

Add an option to allocate uncached memory for dma_alloc_coherent from
the global dma_coherent_default_memory.  This will allow to move
arm-nommu (and eventually other platforms) to use generic code for
allocating uncached memory from a pre-populated pool.

Note that this is a different pool from the one that platforms that
can remap at runtime use for GFP_ATOMIC allocations for now, although
there might be opportunities to eventually end up with a common codebase
for the two use cases.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Dillon Min <dillon.minfei@gmail.com>
This commit is contained in:
Christoph Hellwig 2021-06-23 14:21:16 +02:00
parent 2a047e0662
commit faf4ef823a
2 changed files with 19 additions and 0 deletions
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4
kernel/dma/Kconfig
View File

@ -93,6 +93,10 @@ config DMA_COHERENT_POOL
select GENERIC_ALLOCATOR
bool
config DMA_GLOBAL_POOL
select DMA_DECLARE_COHERENT
bool
config DMA_REMAP
bool
depends on MMU

15
kernel/dma/direct.c
View File

@ -156,9 +156,14 @@ void *dma_direct_alloc(struct device *dev, size_t size,
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
!IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
!IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
!dev_is_dma_coherent(dev))
return arch_dma_alloc(dev, size, dma_handle, gfp, attrs);
if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
!dev_is_dma_coherent(dev))
return dma_alloc_from_global_coherent(dev, size, dma_handle);
/*
* Remapping or decrypting memory may block. If either is required and
* we can't block, allocate the memory from the atomic pools.
@ -255,11 +260,19 @@ void dma_direct_free(struct device *dev, size_t size,
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED) &&
!IS_ENABLED(CONFIG_DMA_DIRECT_REMAP) &&
!IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
!dev_is_dma_coherent(dev)) {
arch_dma_free(dev, size, cpu_addr, dma_addr, attrs);
return;
}
if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
!dev_is_dma_coherent(dev)) {
if (!dma_release_from_global_coherent(page_order, cpu_addr))
WARN_ON_ONCE(1);
return;
}
/* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */
if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
@ -462,6 +475,8 @@ int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
return ret;
if (dma_mmap_from_global_coherent(vma, cpu_addr, size, &ret))
return ret;
if (vma->vm_pgoff >= count || user_count > count - vma->vm_pgoff)
return -ENXIO;