On Thu, 06 Oct 2011 15:54:47 +0200 Marek Szyprowski m.szyprowski@samsung.com wrote:
This patch adds support for CMA to dma-mapping subsystem for ARM architecture. By default a global CMA area is used, but specific devices are allowed to have their private memory areas if required (they can be created with dma_declare_contiguous() function during board initialization).
Contiguous memory areas reserved for DMA are remapped with 2-level page tables on boot. Once a buffer is requested, a low memory kernel mapping is updated to to match requested memory access type.
GFP_ATOMIC allocations are performed from special pool which is created early during boot. This way remapping page attributes is not needed on allocation time.
CMA has been enabled unconditionally for ARMv6+ systems.
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--- /dev/null +++ b/arch/arm/include/asm/dma-contiguous.h @@ -0,0 +1,33 @@ +#ifndef ASMARM_DMA_CONTIGUOUS_H +#define ASMARM_DMA_CONTIGUOUS_H
+#ifdef __KERNEL__
+#include <linux/device.h> +#include <linux/dma-contiguous.h>
+#ifdef CONFIG_CMA
+#define MAX_CMA_AREAS (8)
This was already defined in include/linux/dma-contiguous.h. The compiler didn't warn because it was defined to the same value. Sort it out, please?
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+static int __init early_coherent_pool(char *p) +{
- coherent_pool_size = memparse(p, &p);
- return 0;
+} +early_param("coherent_pool", early_coherent_pool);
Is there user documentation for the new parameter?
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+struct dma_contiguous_early_reserve {
- phys_addr_t base;
- unsigned long size;
+};
+static struct dma_contiguous_early_reserve +dma_mmu_remap[MAX_CMA_AREAS] __initdata;
Tab the continuation line to the right a bit.
+static int dma_mmu_remap_num __initdata;
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+static void *__alloc_from_pool(struct device *dev, size_t size,
struct page **ret_page)+{
- struct arm_vmregion *c;
- size_t align;
- if (!coherent_head.vm_start) {
printk(KERN_ERR "%s: coherent pool not initialised!\n",__func__);dump_stack();return NULL;- }
- align = 1 << fls(size - 1);
Is there a roundup_pow_of_two() hiding in there?
- c = arm_vmregion_alloc(&coherent_head, align, size, 0);
- if (c) {
void *ptr = (void *)c->vm_start;struct page *page = virt_to_page(ptr);*ret_page = page;return ptr;- }
- return NULL;
+}
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