dma-mapping: use unsigned long for dma_attrs

The dma-mapping core and the implementations do not change the DMA
attributes passed by pointer.  Thus the pointer can point to const data.
However the attributes do not have to be a bitfield.  Instead unsigned
long will do fine:

1. This is just simpler.  Both in terms of reading the code and setting
   attributes.  Instead of initializing local attributes on the stack
   and passing pointer to it to dma_set_attr(), just set the bits.

2. It brings safeness and checking for const correctness because the
   attributes are passed by value.

Semantic patches for this change (at least most of them):

    virtual patch
    virtual context

    @r@
    identifier f, attrs;

    @@
    f(...,
    - struct dma_attrs *attrs
    + unsigned long attrs
    , ...)
    {
    ...
    }

    @@
    identifier r.f;
    @@
    f(...,
    - NULL
    + 0
     )

and

    // Options: --all-includes
    virtual patch
    virtual context

    @r@
    identifier f, attrs;
    type t;

    @@
    t f(..., struct dma_attrs *attrs);

    @@
    identifier r.f;
    @@
    f(...,
    - NULL
    + 0
     )

Link: http://lkml.kernel.org/r/1468399300-5399-2-git-send-email-k.kozlowski@samsung.com
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Acked-by: Vineet Gupta <vgupta@synopsys.com>
Acked-by: Robin Murphy <robin.murphy@arm.com>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no>
Acked-by: Mark Salter <msalter@redhat.com> [c6x]
Acked-by: Jesper Nilsson <jesper.nilsson@axis.com> [cris]
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch> [drm]
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Acked-by: Joerg Roedel <jroedel@suse.de> [iommu]
Acked-by: Fabien Dessenne <fabien.dessenne@st.com> [bdisp]
Reviewed-by: Marek Szyprowski <m.szyprowski@samsung.com> [vb2-core]
Acked-by: David Vrabel <david.vrabel@citrix.com> [xen]
Acked-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> [xen swiotlb]
Acked-by: Joerg Roedel <jroedel@suse.de> [iommu]
Acked-by: Richard Kuo <rkuo@codeaurora.org> [hexagon]
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org> [m68k]
Acked-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> [s390]
Acked-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Acked-by: Hans-Christian Noren Egtvedt <egtvedt@samfundet.no> [avr32]
Acked-by: Vineet Gupta <vgupta@synopsys.com> [arc]
Acked-by: Robin Murphy <robin.murphy@arm.com> [arm64 and dma-iommu]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 7 deletions

diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c b/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
index 6b8f2a19b2d9..a6a7fa0d7679 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/instmem/gk20a.c
@@ -109,7 +109,7 @@ struct gk20a_instmem {
 	u16 iommu_bit;
 
 	/* Only used by DMA API */
-	struct dma_attrs attrs;
+	unsigned long attrs;
 };
 #define gk20a_instmem(p) container_of((p), struct gk20a_instmem, base)
 
@@ -293,7 +293,7 @@ gk20a_instobj_dtor_dma(struct nvkm_memory *memory)
 		goto out;
 
 	dma_free_attrs(dev, node->base.mem.size << PAGE_SHIFT, node->base.vaddr,
-		       node->handle, &imem->attrs);
+		       node->handle, imem->attrs);
 
 out:
 	return node;
@@ -386,7 +386,7 @@ gk20a_instobj_ctor_dma(struct gk20a_instmem *imem, u32 npages, u32 align,
 
 	node->base.vaddr = dma_alloc_attrs(dev, npages << PAGE_SHIFT,
 					   &node->handle, GFP_KERNEL,
-					   &imem->attrs);
+					   imem->attrs);
 	if (!node->base.vaddr) {
 		nvkm_error(subdev, "cannot allocate DMA memory\n");
 		return -ENOMEM;
@@ -597,10 +597,9 @@ gk20a_instmem_new(struct nvkm_device *device, int index,
 
 		nvkm_info(&imem->base.subdev, "using IOMMU\n");
 	} else {
-		init_dma_attrs(&imem->attrs);
-		dma_set_attr(DMA_ATTR_NON_CONSISTENT, &imem->attrs);
-		dma_set_attr(DMA_ATTR_WEAK_ORDERING, &imem->attrs);
-		dma_set_attr(DMA_ATTR_WRITE_COMBINE, &imem->attrs);
+		imem->attrs = DMA_ATTR_NON_CONSISTENT |
+			      DMA_ATTR_WEAK_ORDERING |
+			      DMA_ATTR_WRITE_COMBINE;
 
 		nvkm_info(&imem->base.subdev, "using DMA API\n");
 	}