[PATCH v3 05/16] gpu: host1x: Use direct DMA with IOMMU API usage

Thierry Reding
2019-02-01T13:28:26Z

If we use the IOMMU API directly to map buffers into host1x' IOVA space,
we must make sure that the DMA API doesn't already set up a mapping, or
else translation will fail.

The direct DMA API allows us to allocate memory that will not be mapped
through an IOMMU automatically.

Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>
---
drivers/gpu/host1x/cdma.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/host1x/cdma.c b/drivers/gpu/host1x/cdma.c
index e2d106fa3c0b..a96c4dd1e449 100644
--- a/drivers/gpu/host1x/cdma.c
+++ b/drivers/gpu/host1x/cdma.c
@@ -19,6 +19,7 @@

#include <asm/cacheflush.h>
#include <linux/device.h>
+#include <linux/dma-direct.h>
#include <linux/dma-mapping.h>
#include <linux/host1x.h>
#include <linux/interrupt.h>
@@ -70,6 +71,7 @@ static void host1x_pushbuffer_destroy(struct push_buffer *pb)
*/
static int host1x_pushbuffer_init(struct push_buffer *pb)
{
+ unsigned long attrs = DMA_ATTR_WRITE_COMBINE;
struct host1x_cdma *cdma = pb_to_cdma(pb);
struct host1x *host1x = cdma_to_host1x(cdma);
struct iova *alloc;
@@ -91,8 +93,8 @@ static int host1x_pushbuffer_init(struct push_buffer *pb)

size = iova_align(&host1x->iova, size);

- pb->mapped = dma_alloc_wc(host1x->dev, size, &pb->phys,
- GFP_KERNEL);
+ pb->mapped = dma_direct_alloc(host1x->dev, size, &pb->phys,
+ GFP_KERNEL, attrs);
if (!pb->mapped)
return -ENOMEM;

@@ -127,7 +129,10 @@ static int host1x_pushbuffer_init(struct push_buffer *pb)
iommu_free_iova:
__free_iova(&host1x->iova, alloc);
iommu_free_mem:
- dma_free_wc(host1x->dev, size, pb->mapped, pb->phys);
+ if (host1x->domain)
+ dma_direct_free(host1x->dev, size, pb->mapped, pb->phys, attrs);
+ else
+ dma_free_wc(host1x->dev, size, pb->mapped, pb->phys);

return err;
}