From a46b6b2d4d49d3fdb6a2ef47455dc170fbce48b7 Mon Sep 17 00:00:00 2001 From: Rebecca Schultz Zavin Date: Fri, 13 Dec 2013 14:23:46 -0800 Subject: [PATCH] gpu: ion: Set the dma_address of the sg list at alloc time This patch sets the dma_address field of the sglist representing an allocation at allocation time. This technically breaks the dma api which states that these addresses should be set when a particular device takes ownership of a buffer via the dma_map apis. In the case of our systems the only dma address space is physical addresses. Additionally, we can not afford the overhead of calling dma_map_sg from this location as it implies a cache invalidate that is not necessary if the memory was previously mapped cached. Instead, the expectation is that memory being returned from the heaps is ready for dma in that if any cached mappings of that memory exist they have been invalidated. Signed-off-by: Rebecca Schultz Zavin [jstultz: modified patch to apply to staging directory] Signed-off-by: John Stultz Signed-off-by: Greg Kroah-Hartman --- drivers/staging/android/ion/ion.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/staging/android/ion/ion.c b/drivers/staging/android/ion/ion.c index 552a86a94f61..ddfe49a8eaa6 100644 --- a/drivers/staging/android/ion/ion.c +++ b/drivers/staging/android/ion/ion.c @@ -136,7 +136,8 @@ static struct ion_buffer *ion_buffer_create(struct ion_heap *heap, { struct ion_buffer *buffer; struct sg_table *table; - int ret; + struct scatterlist *sg; + int i, ret; buffer = kzalloc(sizeof(struct ion_buffer), GFP_KERNEL); if (!buffer) @@ -163,6 +164,16 @@ static struct ion_buffer *ion_buffer_create(struct ion_heap *heap, buffer->sg_table = table; mutex_init(&buffer->lock); + /* this will set up dma addresses for the sglist -- it is not + technically correct as per the dma api -- a specific + device isn't really taking ownership here. However, in practice on + our systems the only dma_address space is physical addresses. + Additionally, we can't afford the overhead of invalidating every + allocation via dma_map_sg. The implicit contract here is that + memory comming from the heaps is ready for dma, ie if it has a + cached mapping that mapping has been invalidated */ + for_each_sg(buffer->sg_table->sgl, sg, buffer->sg_table->nents, i) + sg_dma_address(sg) = sg_phys(sg); ion_buffer_add(dev, buffer); return buffer; } -- 2.20.1