Re: [Linaro-mm-sig] [RFC PATCH 10/12] staging: android: ion: Use CMA APIs directly

Hi Laura,

Thank you for the patch.

On Thursday 02 Mar 2017 13:44:42 Laura Abbott wrote:

When CMA was first introduced, its primary use was for DMA allocation and the only way to get CMA memory was to call dma_alloc_coherent. This put Ion in an awkward position since there was no device structure readily available and setting one up messed up the coherency model. These days, CMA can be allocated directly from the APIs. Switch to using this model to avoid needing a dummy device. This also avoids awkward caching questions.

If the DMA mapping API isn't suitable for today's requirements anymore, I believe that's what needs to be fixed, instead of working around the problem by introducing another use-case-specific API.

Signed-off-by: Laura Abbott labbott@redhat.com

drivers/staging/android/ion/ion_cma_heap.c | 97 +++++++-------------------- 1 file changed, 26 insertions(+), 71 deletions(-)

diff --git a/drivers/staging/android/ion/ion_cma_heap.c b/drivers/staging/android/ion/ion_cma_heap.c index d562fd7..6838825 100644 --- a/drivers/staging/android/ion/ion_cma_heap.c +++ b/drivers/staging/android/ion/ion_cma_heap.c @@ -19,24 +19,19 @@ #include <linux/slab.h> #include <linux/errno.h> #include <linux/err.h> -#include <linux/dma-mapping.h> +#include <linux/cma.h> +#include <linux/scatterlist.h>

#include "ion.h" #include "ion_priv.h"

struct ion_cma_heap { struct ion_heap heap;

• struct device *dev;

• struct cma *cma;

};

#define to_cma_heap(x) container_of(x, struct ion_cma_heap, heap)

-struct ion_cma_buffer_info {

• void *cpu_addr;
• dma_addr_t handle;
• struct sg_table *table;

-};

/* ION CMA heap operations functions */ static int ion_cma_allocate(struct ion_heap *heap, struct ion_buffer *buffer, @@ -44,93 +39,53 @@ static int ion_cma_allocate(struct ion_heap *heap, struct ion_buffer *buffer, unsigned long flags) { struct ion_cma_heap *cma_heap = to_cma_heap(heap);

• struct device *dev = cma_heap->dev;
• struct ion_cma_buffer_info *info;
• dev_dbg(dev, "Request buffer allocation len %ld\n", len);
• if (buffer->flags & ION_FLAG_CACHED)

• return -EINVAL;
  

• struct sg_table *table;
• struct page *pages;
• int ret;

• info = kzalloc(sizeof(*info), GFP_KERNEL);
• if (!info)

• pages = cma_alloc(cma_heap->cma, len, 0);
• if (!pages) return -ENOMEM;

• info->cpu_addr = dma_alloc_coherent(dev, len, &(info->handle),

• 				GFP_HIGHUSER | __GFP_ZERO);
  

• if (!info->cpu_addr) {

• dev_err(dev, "Fail to allocate buffer\n");
  

• table = kmalloc(sizeof(struct sg_table), GFP_KERNEL);
• if (!table) goto err;

• }

• info->table = kmalloc(sizeof(*info->table), GFP_KERNEL);

• if (!info->table)

• ret = sg_alloc_table(table, 1, GFP_KERNEL);
• if (ret) goto free_mem;

• if (dma_get_sgtable(dev, info->table, info->cpu_addr, info->handle,

• 	    len))
  

• goto free_table;
  

• /* keep this for memory release */
• buffer->priv_virt = info;
• buffer->sg_table = info->table;
• dev_dbg(dev, "Allocate buffer %p\n", buffer);

• sg_set_page(table->sgl, pages, len, 0);
• buffer->priv_virt = pages;
• buffer->sg_table = table; return 0;

-free_table:

• kfree(info->table);

free_mem:

• dma_free_coherent(dev, len, info->cpu_addr, info->handle);

• kfree(table);

err:

• kfree(info);

• cma_release(cma_heap->cma, pages, buffer->size); return -ENOMEM;

}

static void ion_cma_free(struct ion_buffer *buffer) { struct ion_cma_heap *cma_heap = to_cma_heap(buffer->heap);

• struct device *dev = cma_heap->dev;
• struct ion_cma_buffer_info *info = buffer->priv_virt;

• struct page *pages = buffer->priv_virt;

• dev_dbg(dev, "Release buffer %p\n", buffer); /* release memory */
• dma_free_coherent(dev, buffer->size, info->cpu_addr, info->handle);

• cma_release(cma_heap->cma, pages, buffer->size); /* release sg table */

• sg_free_table(info->table);
• kfree(info->table);
• kfree(info);

-}

-static int ion_cma_mmap(struct ion_heap *mapper, struct ion_buffer *buffer,

• 	struct vm_area_struct *vma)
  

-{

• struct ion_cma_heap *cma_heap = to_cma_heap(buffer->heap);
• struct device *dev = cma_heap->dev;
• struct ion_cma_buffer_info *info = buffer->priv_virt;
• return dma_mmap_coherent(dev, vma, info->cpu_addr, info->handle,

• 		 buffer->size);
  

-}

-static void *ion_cma_map_kernel(struct ion_heap *heap,

• 		struct ion_buffer *buffer)
  

-{

• struct ion_cma_buffer_info *info = buffer->priv_virt;
• /* kernel memory mapping has been done at allocation time */
• return info->cpu_addr;

-}

-static void ion_cma_unmap_kernel(struct ion_heap *heap,

• 		 struct ion_buffer *buffer)
  

-{

• sg_free_table(buffer->sg_table);
• kfree(buffer->sg_table);

}

static struct ion_heap_ops ion_cma_ops = { .allocate = ion_cma_allocate, .free = ion_cma_free,

• .map_user = ion_cma_mmap,
• .map_kernel = ion_cma_map_kernel,
• .unmap_kernel = ion_cma_unmap_kernel,

• .map_user = ion_heap_map_user,
• .map_kernel = ion_heap_map_kernel,
• .unmap_kernel = ion_heap_unmap_kernel,

};

struct ion_heap *ion_cma_heap_create(struct ion_platform_heap *data) @@ -147,7 +102,7 @@ struct ion_heap *ion_cma_heap_create(struct ion_platform_heap *data) * get device from private heaps data, later it will be * used to make the link with reserved CMA memory */

• cma_heap->dev = data->priv;

• cma_heap->cma = data->priv; cma_heap->heap.type = ION_HEAP_TYPE_DMA; return &cma_heap->heap;

}