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dma-mapping: add support for dma-coherent-hint-cached

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When clients configure their device as dma-coherent-hint-cached this will
result in the memory framework only trying to DMA map buffers as
IO-coherent if the framework is confident that the buffers are mapped as
cached in the CPU.

Clients should configure their device as dma-coherent-hint-cached instead
of dma-coherent when they need to DMA map both buffers that have cached
CPU mappings and other buffers which have uncached CPU mappings. By using
dma-coherent-hint-cached the framework will ensure that the client's
buffers with uncached CPU mappings don't get DMA mapped as IO-coherent.

Change-Id: I990184b54d4148bf952cc672ec267b51efd81473
Signed-off-by: Liam Mark <lmark@codeaurora.org>
This commit is contained in:
Liam Mark 2020-02-20 10:19:06 -08:00
commit 707e9d34cf
10 changed files with 141 additions and 19 deletions
Download patch file Download diff file Expand all files Collapse all files

10
kernel/dma/Kconfig
View file

@ -77,6 +77,16 @@ config DMA_DIRECT_REMAP
bool
select DMA_REMAP
config DMA_COHERENT_HINT_CACHED
bool "DMA coherent hint cached"
help
Enabling this feature allows client to configure their device so
that the memory framework will only try to DMA map buffers to the device
as IO-coherent if the framework is confident that the buffers are mapped
to the CPU as cached.
If unsure, say "n".
config DMA_CMA
bool "DMA Contiguous Memory Allocator"
depends on HAVE_DMA_CONTIGUOUS && CMA

40
kernel/dma/mapping.c
View file

@ -46,6 +46,18 @@ static int dmam_match(struct device *dev, void *res, void *match_data)
return 0;
}
static bool is_dma_coherent(struct device *dev, unsigned long attrs)
{
if (attrs & DMA_ATTR_FORCE_COHERENT)
return true;
else if (attrs & DMA_ATTR_FORCE_NON_COHERENT)
return false;
else if (dev_is_dma_coherent(dev))
return true;
else
return false;
}
/**
* dmam_free_coherent - Managed dma_free_coherent()
* @dev: Device to free coherent memory for
@ -116,7 +128,7 @@ int dma_common_get_sgtable(struct device *dev, struct sg_table *sgt,
struct page *page;
int ret;
if (!dev_is_dma_coherent(dev)) {
if (!is_dma_coherent(dev, attrs)) {
unsigned long pfn;
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_COHERENT_TO_PFN))
@ -154,6 +166,9 @@ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
{
const struct dma_map_ops *ops = get_dma_ops(dev);
if (dev_is_dma_coherent_hint_cached(dev))
attrs |= DMA_ATTR_FORCE_COHERENT;
if (dma_is_direct(ops))
return dma_common_get_sgtable(dev, sgt, cpu_addr, dma_addr,
size, attrs);
@ -164,18 +179,6 @@ int dma_get_sgtable_attrs(struct device *dev, struct sg_table *sgt,
EXPORT_SYMBOL(dma_get_sgtable_attrs);
#ifdef CONFIG_MMU
static bool is_dma_coherent(struct device *dev, unsigned long attrs)
{
if (attrs & DMA_ATTR_FORCE_COHERENT)
return true;
else if (attrs & DMA_ATTR_FORCE_NON_COHERENT)
return false;
else if (dev_is_dma_coherent(dev))
return true;
else
return false;
}
/*
* Return the page attributes used for mapping dma_alloc_* memory, either in
* kernel space if remapping is needed, or to userspace through dma_mmap_*.
@ -216,7 +219,7 @@ int dma_common_mmap(struct device *dev, struct vm_area_struct *vma,
if (off >= count || user_count > count - off)
return -ENXIO;
if (!dev_is_dma_coherent(dev)) {
if (!is_dma_coherent(dev, attrs)) {
if (!IS_ENABLED(CONFIG_ARCH_HAS_DMA_COHERENT_TO_PFN))
return -ENXIO;
@ -275,6 +278,9 @@ int dma_mmap_attrs(struct device *dev, struct vm_area_struct *vma,
{
const struct dma_map_ops *ops = get_dma_ops(dev);
if (dev_is_dma_coherent_hint_cached(dev))
attrs |= DMA_ATTR_FORCE_COHERENT;
if (dma_is_direct(ops))
return dma_common_mmap(dev, vma, cpu_addr, dma_addr, size,
attrs);
@ -315,6 +321,9 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle,
WARN_ON(!of_reserved_mem_device_is_init(dev));
if (dev_is_dma_coherent_hint_cached(dev))
attrs |= DMA_ATTR_FORCE_COHERENT;
if (dma_alloc_from_dev_coherent(dev, size, dma_handle, &cpu_addr))
return cpu_addr;
@ -338,6 +347,9 @@ void dma_free_attrs(struct device *dev, size_t size, void *cpu_addr,
{
const struct dma_map_ops *ops = get_dma_ops(dev);
if (dev_is_dma_coherent_hint_cached(dev))
attrs |= DMA_ATTR_FORCE_COHERENT;
if (dma_release_from_dev_coherent(dev, get_order(size), cpu_addr))
return;
/*