diff mbox

[v2,4/7] media: vb2-dma-contig: add helper for setting dma max seg size

Message ID 1449669502-24601-5-git-send-email-m.szyprowski@samsung.com
State New
Headers show

Commit Message

Marek Szyprowski Dec. 9, 2015, 1:58 p.m. UTC
Add a helper function for device drivers to set DMA's max_seg_size.
Setting it to largest possible value lets DMA-mapping API always create
contiguous mappings in DMA address space. This is essential for all
devices, which use dma-contig videobuf2 memory allocator and shared
buffers.

Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

---
 drivers/media/v4l2-core/videobuf2-dma-contig.c | 15 +++++++++++++++
 include/media/videobuf2-dma-contig.h           |  1 +
 2 files changed, 16 insertions(+)

-- 
1.9.2

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Comments

Marek Szyprowski Dec. 14, 2015, 9:20 a.m. UTC | #1
Hello,

On 2015-12-13 20:57, Laurent Pinchart wrote:
> Hi Marek,

>

> Thank you for the patch.

>

> On Wednesday 09 December 2015 14:58:19 Marek Szyprowski wrote:

>> Add a helper function for device drivers to set DMA's max_seg_size.

>> Setting it to largest possible value lets DMA-mapping API always create

>> contiguous mappings in DMA address space. This is essential for all

>> devices, which use dma-contig videobuf2 memory allocator and shared

>> buffers.

>>

>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>

>> ---

>>   drivers/media/v4l2-core/videobuf2-dma-contig.c | 15 +++++++++++++++

>>   include/media/videobuf2-dma-contig.h           |  1 +

>>   2 files changed, 16 insertions(+)

>>

>> diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c

>> b/drivers/media/v4l2-core/videobuf2-dma-contig.c index c331272..628518d

>> 100644

>> --- a/drivers/media/v4l2-core/videobuf2-dma-contig.c

>> +++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c

>> @@ -742,6 +742,21 @@ void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)

>>   }

>>   EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);

>>

>> +int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size)

>> +{

>> +	if (!dev->dma_parms) {

> When can this function be called with dev->dma_parms not NULL ?


When one loads a module with multimedia driver (which calls this 
function), then
unloads and loads it again. It is rather safe to have this check.

>> +		dev->dma_parms = devm_kzalloc(dev, sizeof(dev->dma_parms),

>> +					      GFP_KERNEL);

>> +		if (!dev->dma_parms)

>> +			return -ENOMEM;

>> +	}

>> +	if (dma_get_max_seg_size(dev) < size)

>> +		return dma_set_max_seg_size(dev, size);

>> +

>> +	return 0;

>> +}

>> +EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size);

>> +

>>   MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");

>>   MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");

>>   MODULE_LICENSE("GPL");

>> diff --git a/include/media/videobuf2-dma-contig.h

>> b/include/media/videobuf2-dma-contig.h index c33dfa6..0e6ba64 100644

>> --- a/include/media/videobuf2-dma-contig.h

>> +++ b/include/media/videobuf2-dma-contig.h

>> @@ -26,6 +26,7 @@ vb2_dma_contig_plane_dma_addr(struct vb2_buffer *vb,

>> unsigned int plane_no)

>>

>>   void *vb2_dma_contig_init_ctx(struct device *dev);

>>   void vb2_dma_contig_cleanup_ctx(void *alloc_ctx);

>> +int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size);

>>

>>   extern const struct vb2_mem_ops vb2_dma_contig_memops;


Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

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diff mbox

Patch

diff --git a/drivers/media/v4l2-core/videobuf2-dma-contig.c b/drivers/media/v4l2-core/videobuf2-dma-contig.c
index c331272..628518d 100644
--- a/drivers/media/v4l2-core/videobuf2-dma-contig.c
+++ b/drivers/media/v4l2-core/videobuf2-dma-contig.c
@@ -742,6 +742,21 @@  void vb2_dma_contig_cleanup_ctx(void *alloc_ctx)
 }
 EXPORT_SYMBOL_GPL(vb2_dma_contig_cleanup_ctx);
 
+int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size)
+{
+	if (!dev->dma_parms) {
+		dev->dma_parms = devm_kzalloc(dev, sizeof(dev->dma_parms),
+					      GFP_KERNEL);
+		if (!dev->dma_parms)
+			return -ENOMEM;
+	}
+	if (dma_get_max_seg_size(dev) < size)
+		return dma_set_max_seg_size(dev, size);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size);
+
 MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
 MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
 MODULE_LICENSE("GPL");
diff --git a/include/media/videobuf2-dma-contig.h b/include/media/videobuf2-dma-contig.h
index c33dfa6..0e6ba64 100644
--- a/include/media/videobuf2-dma-contig.h
+++ b/include/media/videobuf2-dma-contig.h
@@ -26,6 +26,7 @@  vb2_dma_contig_plane_dma_addr(struct vb2_buffer *vb, unsigned int plane_no)
 
 void *vb2_dma_contig_init_ctx(struct device *dev);
 void vb2_dma_contig_cleanup_ctx(void *alloc_ctx);
+int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size);
 
 extern const struct vb2_mem_ops vb2_dma_contig_memops;