Re: [PATCHv3 13/22] staging: android: ion: Use CMA APIs directly

[Greg Kroah-Hartman]

On Mon, Apr 03, 2017 at 11:57:55AM -0700, 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 mitigates some of
> the caching problems (e.g. dma_alloc_coherent only returning uncached
> memory).
> 
> Signed-off-by: Laura Abbott 
> ---
>  drivers/staging/android/ion/Kconfig|  7 +++
>  drivers/staging/android/ion/Makefile   |  3 +-
>  drivers/staging/android/ion/ion_cma_heap.c | 97 
> --
>  3 files changed, 35 insertions(+), 72 deletions(-)
> 
> diff --git a/drivers/staging/android/ion/Kconfig 
> b/drivers/staging/android/ion/Kconfig
> index 206c4de..15108c4 100644
> --- a/drivers/staging/android/ion/Kconfig
> +++ b/drivers/staging/android/ion/Kconfig
> @@ -10,3 +10,10 @@ menuconfig ION
> If you're not using Android its probably safe to
> say N here.
>  
> +config ION_CMA_HEAP
> + bool "Ion CMA heap support"
> + depends on ION && CMA
> + help
> +   Choose this option to enable CMA heaps with Ion. This heap is backed
> +   by the Contiguous Memory Allocator (CMA). If your system has these
> +   regions, you should say Y here.
> diff --git a/drivers/staging/android/ion/Makefile 
> b/drivers/staging/android/ion/Makefile
> index 26672a0..66d0c4a 100644
> --- a/drivers/staging/android/ion/Makefile
> +++ b/drivers/staging/android/ion/Makefile
> @@ -1,6 +1,7 @@
>  obj-$(CONFIG_ION) += ion.o ion-ioctl.o ion_heap.o \
>   ion_page_pool.o ion_system_heap.o \
> - ion_carveout_heap.o ion_chunk_heap.o ion_cma_heap.o
> + ion_carveout_heap.o ion_chunk_heap.o
> +obj-$(CONFIG_ION_CMA_HEAP) += ion_cma_heap.o
>  ifdef CONFIG_COMPAT
>  obj-$(CONFIG_ION) += compat_ion.o
>  endif
> diff --git a/drivers/staging/android/ion/ion_cma_heap.c 
> b/drivers/staging/android/ion/ion_cma_heap.c
> index d562fd7..f3e0f59 100644
> --- a/drivers/staging/android/ion/ion_cma_heap.c
> +++ b/drivers/staging/android/ion/ion_cma_heap.c
> @@ -19,24 +19,19 @@
>  #include 
>  #include 
>  #include 
> -#include 
> +#include 
> +#include 
>  
>  #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, GFP_KERNEL);
> + 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 

Re: [PATCHv3 13/22] staging: android: ion: Use CMA APIs directly

[Laura Abbott]

On 04/10/2017 11:47 PM, Laurent Pinchart wrote:
> Hi Laura,
> 
> Thank you for the patch.
> 
> On Monday 03 Apr 2017 11:57:55 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 mitigates some of
>> the caching problems (e.g. dma_alloc_coherent only returning uncached
>> memory).
> 
> Do we have a guarantee that the DMA mapping API, which we have to use for 
> cache handling, will always support memory we allocate directly from CMA 
> behind its back ?
> 

CMA pages are no different than other pages allocated via the buddy
allocator. There should be no issue passing that memory to the
streaming API.

Thanks,
Laura

>> Signed-off-by: Laura Abbott 
>> ---
>>  drivers/staging/android/ion/Kconfig|  7 +++
>>  drivers/staging/android/ion/Makefile   |  3 +-
>>  drivers/staging/android/ion/ion_cma_heap.c | 97 +++
>>  3 files changed, 35 insertions(+), 72 deletions(-)
>>
>> diff --git a/drivers/staging/android/ion/Kconfig
>> b/drivers/staging/android/ion/Kconfig index 206c4de..15108c4 100644
>> --- a/drivers/staging/android/ion/Kconfig
>> +++ b/drivers/staging/android/ion/Kconfig
>> @@ -10,3 +10,10 @@ menuconfig ION
>>If you're not using Android its probably safe to
>>say N here.
>>
>> +config ION_CMA_HEAP
>> +bool "Ion CMA heap support"
>> +depends on ION && CMA
>> +help
>> +  Choose this option to enable CMA heaps with Ion. This heap is backed
>> +  by the Contiguous Memory Allocator (CMA). If your system has these
>> +  regions, you should say Y here.
>> diff --git a/drivers/staging/android/ion/Makefile
>> b/drivers/staging/android/ion/Makefile index 26672a0..66d0c4a 100644
>> --- a/drivers/staging/android/ion/Makefile
>> +++ b/drivers/staging/android/ion/Makefile
>> @@ -1,6 +1,7 @@
>>  obj-$(CONFIG_ION) +=ion.o ion-ioctl.o ion_heap.o \
>>  ion_page_pool.o ion_system_heap.o \
>> -ion_carveout_heap.o ion_chunk_heap.o ion_cma_heap.o
>> +ion_carveout_heap.o ion_chunk_heap.o
>> +obj-$(CONFIG_ION_CMA_HEAP) += ion_cma_heap.o
>>  ifdef CONFIG_COMPAT
>>  obj-$(CONFIG_ION) += compat_ion.o
>>  endif
>> diff --git a/drivers/staging/android/ion/ion_cma_heap.c
>> b/drivers/staging/android/ion/ion_cma_heap.c index d562fd7..f3e0f59 100644
>> --- a/drivers/staging/android/ion/ion_cma_heap.c
>> +++ b/drivers/staging/android/ion/ion_cma_heap.c
>> @@ -19,24 +19,19 @@
>>  #include 
>>  #include 
>>  #include 
>> -#include 
>> +#include 
>> +#include 
>>
>>  #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, GFP_KERNEL);
>> +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);
>> +

Re: [PATCHv3 13/22] staging: android: ion: Use CMA APIs directly

[Laurent Pinchart]

Hi Laura,

Thank you for the patch.

On Monday 03 Apr 2017 11:57:55 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 mitigates some of
> the caching problems (e.g. dma_alloc_coherent only returning uncached
> memory).

Do we have a guarantee that the DMA mapping API, which we have to use for 
cache handling, will always support memory we allocate directly from CMA 
behind its back ?

> Signed-off-by: Laura Abbott 
> ---
>  drivers/staging/android/ion/Kconfig|  7 +++
>  drivers/staging/android/ion/Makefile   |  3 +-
>  drivers/staging/android/ion/ion_cma_heap.c | 97 +++
>  3 files changed, 35 insertions(+), 72 deletions(-)
> 
> diff --git a/drivers/staging/android/ion/Kconfig
> b/drivers/staging/android/ion/Kconfig index 206c4de..15108c4 100644
> --- a/drivers/staging/android/ion/Kconfig
> +++ b/drivers/staging/android/ion/Kconfig
> @@ -10,3 +10,10 @@ menuconfig ION
> If you're not using Android its probably safe to
> say N here.
> 
> +config ION_CMA_HEAP
> + bool "Ion CMA heap support"
> + depends on ION && CMA
> + help
> +   Choose this option to enable CMA heaps with Ion. This heap is backed
> +   by the Contiguous Memory Allocator (CMA). If your system has these
> +   regions, you should say Y here.
> diff --git a/drivers/staging/android/ion/Makefile
> b/drivers/staging/android/ion/Makefile index 26672a0..66d0c4a 100644
> --- a/drivers/staging/android/ion/Makefile
> +++ b/drivers/staging/android/ion/Makefile
> @@ -1,6 +1,7 @@
>  obj-$(CONFIG_ION) += ion.o ion-ioctl.o ion_heap.o \
>   ion_page_pool.o ion_system_heap.o \
> - ion_carveout_heap.o ion_chunk_heap.o ion_cma_heap.o
> + ion_carveout_heap.o ion_chunk_heap.o
> +obj-$(CONFIG_ION_CMA_HEAP) += ion_cma_heap.o
>  ifdef CONFIG_COMPAT
>  obj-$(CONFIG_ION) += compat_ion.o
>  endif
> diff --git a/drivers/staging/android/ion/ion_cma_heap.c
> b/drivers/staging/android/ion/ion_cma_heap.c index d562fd7..f3e0f59 100644
> --- a/drivers/staging/android/ion/ion_cma_heap.c
> +++ b/drivers/staging/android/ion/ion_cma_heap.c
> @@ -19,24 +19,19 @@
>  #include 
>  #include 
>  #include 
> -#include 
> +#include 
> +#include 
> 
>  #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, GFP_KERNEL);
> + 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:
> -