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>

2 files changed, 7 insertions, 8 deletions

diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
index fa2ec0cd00e8..7abc550ebc00 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
@@ -54,15 +54,14 @@ struct mtk_drm_gem_obj *mtk_drm_gem_create(struct drm_device *dev,
 
         obj = &mtk_gem->base;
 
-        init_dma_attrs(&mtk_gem->dma_attrs);
-        dma_set_attr(DMA_ATTR_WRITE_COMBINE, &mtk_gem->dma_attrs);
+        mtk_gem->dma_attrs = DMA_ATTR_WRITE_COMBINE;
 
         if (!alloc_kmap)
-                dma_set_attr(DMA_ATTR_NO_KERNEL_MAPPING, &mtk_gem->dma_attrs);
+                mtk_gem->dma_attrs |= DMA_ATTR_NO_KERNEL_MAPPING;
 
         mtk_gem->cookie = dma_alloc_attrs(priv->dma_dev, obj->size,
                                           &mtk_gem->dma_addr, GFP_KERNEL,
-                                          &mtk_gem->dma_attrs);
+                                          mtk_gem->dma_attrs);
         if (!mtk_gem->cookie) {
                 DRM_ERROR("failed to allocate %zx byte dma buffer", obj->size);
                 ret = -ENOMEM;
@@ -93,7 +92,7 @@ void mtk_drm_gem_free_object(struct drm_gem_object *obj)
                 drm_prime_gem_destroy(obj, mtk_gem->sg);
         else
                 dma_free_attrs(priv->dma_dev, obj->size, mtk_gem->cookie,
-                               mtk_gem->dma_addr, &mtk_gem->dma_attrs);
+                               mtk_gem->dma_addr, mtk_gem->dma_attrs);
 
         /* release file pointer to gem object. */
         drm_gem_object_release(obj);
@@ -173,7 +172,7 @@ static int mtk_drm_gem_object_mmap(struct drm_gem_object *obj,
         vma->vm_pgoff = 0;
 
         ret = dma_mmap_attrs(priv->dma_dev, vma, mtk_gem->cookie,
-                             mtk_gem->dma_addr, obj->size, &mtk_gem->dma_attrs);
+                             mtk_gem->dma_addr, obj->size, mtk_gem->dma_attrs);
         if (ret)
                 drm_gem_vm_close(vma);
 
@@ -224,7 +223,7 @@ struct sg_table *mtk_gem_prime_get_sg_table(struct drm_gem_object *obj)
 
         ret = dma_get_sgtable_attrs(priv->dma_dev, sgt, mtk_gem->cookie,
                                     mtk_gem->dma_addr, obj->size,
-                                    &mtk_gem->dma_attrs);
+                                    mtk_gem->dma_attrs);
         if (ret) {
                 DRM_ERROR("failed to allocate sgt, %d\n", ret);
                 kfree(sgt);
diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.h b/drivers/gpu/drm/mediatek/mtk_drm_gem.h
index 3a2a5624a1cb..2752718fa5b2 100644
--- a/drivers/gpu/drm/mediatek/mtk_drm_gem.h
+++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.h
@@ -35,7 +35,7 @@ struct mtk_drm_gem_obj {
         void                    *cookie;
         void                    *kvaddr;
         dma_addr_t              dma_addr;
-        struct dma_attrs        dma_attrs;
+        unsigned long           dma_attrs;
         struct sg_table         *sg;
 };