drm/exynos: fix DMA_ATTR_NO_KERNEL_MAPPING usage

The Exynos DRM driver doesn't follow the correct API when dealing with
dma_{alloc, mmap, free}_attrs functions and the
DMA_ATTR_NO_KERNEL_MAPPING attribute.

When a IOMMU is not available and the DMA_ATTR_NO_KERNEL_MAPPING is
used, the driver should use the pointer returned by dma_alloc_attr() as
a cookie.

The Exynos DRM driver directly uses the non-requested virtual kernel
address returned by the DMA mapping subsystem. This just works now
because the non-IOMMU codepath doesn't obey DMA_ATTR_NO_KERNEL_MAPPING
but we need to fix it before fixing the DMA layer.

Signed-off-by: Carlo Caione <carlo@caione.org>
Acked-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

3 files changed, 14 insertions, 23 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_drm_buf.c b/drivers/gpu/drm/exynos/exynos_drm_buf.c
index 9c8088462c26..24994ba10e28 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_buf.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_buf.c
@@ -63,11 +63,11 @@ static int lowlevel_buffer_allocate(struct drm_device *dev,
                         return -ENOMEM;
                 }
 
-                buf->kvaddr = (void __iomem *)dma_alloc_attrs(dev->dev,
+                buf->cookie = dma_alloc_attrs(dev->dev,
                                         buf->size,
                                         &buf->dma_addr, GFP_KERNEL,
                                         &buf->dma_attrs);
-                if (!buf->kvaddr) {
+                if (!buf->cookie) {
                         DRM_ERROR("failed to allocate buffer.\n");
                         ret = -ENOMEM;
                         goto err_free;
@@ -132,7 +132,7 @@ static void lowlevel_buffer_deallocate(struct drm_device *dev,
         buf->sgt = NULL;
 
         if (!is_drm_iommu_supported(dev)) {
-                dma_free_attrs(dev->dev, buf->size, buf->kvaddr,
+                dma_free_attrs(dev->dev, buf->size, buf->cookie,
                                 (dma_addr_t)buf->dma_addr, &buf->dma_attrs);
                 drm_free_large(buf->pages);
         } else
diff --git a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
index e12ea90c6237..84f8dfe1c5ec 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_fbdev.c
@@ -79,9 +79,9 @@ static int exynos_drm_fbdev_update(struct drm_fb_helper *helper,
                                      struct drm_framebuffer *fb)
 {
         struct fb_info *fbi = helper->fbdev;
-        struct drm_device *dev = helper->dev;
         struct exynos_drm_gem_buf *buffer;
         unsigned int size = fb->width * fb->height * (fb->bits_per_pixel >> 3);
+        unsigned int nr_pages;
         unsigned long offset;
 
         drm_fb_helper_fill_fix(fbi, fb->pitches[0], fb->depth);
@@ -94,25 +94,14 @@ static int exynos_drm_fbdev_update(struct drm_fb_helper *helper,
                 return -EFAULT;
         }
 
-        /* map pages with kernel virtual space. */
+        nr_pages = buffer->size >> PAGE_SHIFT;
+
+        buffer->kvaddr = (void __iomem *) vmap(buffer->pages,
+                        nr_pages, VM_MAP,
+                        pgprot_writecombine(PAGE_KERNEL));
         if (!buffer->kvaddr) {
-                if (is_drm_iommu_supported(dev)) {
-                        unsigned int nr_pages = buffer->size >> PAGE_SHIFT;
-
-                        buffer->kvaddr = (void __iomem *) vmap(buffer->pages,
-                                        nr_pages, VM_MAP,
-                                        pgprot_writecombine(PAGE_KERNEL));
-                } else {
-                        phys_addr_t dma_addr = buffer->dma_addr;
-                        if (dma_addr)
-                                buffer->kvaddr = (void __iomem *)phys_to_virt(dma_addr);
-                        else
-                                buffer->kvaddr = (void __iomem *)NULL;
-                }
-                if (!buffer->kvaddr) {
-                        DRM_ERROR("failed to map pages to kernel space.\n");
-                        return -EIO;
-                }
+                DRM_ERROR("failed to map pages to kernel space.\n");
+                return -EIO;
         }
 
         /* buffer count to framebuffer always is 1 at booting time. */
@@ -313,7 +302,7 @@ static void exynos_drm_fbdev_destroy(struct drm_device *dev,
         struct exynos_drm_gem_obj *exynos_gem_obj = exynos_fbd->exynos_gem_obj;
         struct drm_framebuffer *fb;
 
-        if (is_drm_iommu_supported(dev) && exynos_gem_obj->buffer->kvaddr)
+        if (exynos_gem_obj->buffer->kvaddr)
                 vunmap(exynos_gem_obj->buffer->kvaddr);
 
         /* release drm framebuffer and real buffer */
diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.h b/drivers/gpu/drm/exynos/exynos_drm_gem.h
index ec58fe9c40df..308173cb4f0a 100644
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.h
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.h
@@ -22,6 +22,7 @@
 /*
  * exynos drm gem buffer structure.
  *
+ * @cookie: cookie returned by dma_alloc_attrs
  * @kvaddr: kernel virtual address to allocated memory region.
  * *userptr: user space address.
  * @dma_addr: bus address(accessed by dma) to allocated memory region.
@@ -35,6 +36,7 @@
  *      VM_PFNMAP or not.
  */
 struct exynos_drm_gem_buf {
+        void                    *cookie;
         void __iomem            *kvaddr;
         unsigned long           userptr;
         dma_addr_t              dma_addr;