drm/exynos: gem: rework scatter-list contiguity check on prime import

[platform/kernel/linux-rpi.git] / drivers / gpu / drm / exynos / exynos_drm_gem.c

diff --git a/drivers/gpu/drm/exynos/exynos_drm_gem.c b/drivers/gpu/drm/exynos/exynos_drm_gem.c
index 40514d3..f136efb 100644 (file)
--- a/drivers/gpu/drm/exynos/exynos_drm_gem.c
+++ b/drivers/gpu/drm/exynos/exynos_drm_gem.c
@@ -458,6 +458,29 @@ exynos_drm_gem_prime_import_sg_table(struct drm_device *dev,
        int npages;
        int ret;
 
+       if (sgt->nents < 1)
+               return ERR_PTR(-EINVAL);
+
+       /*
+        * Check if the provided buffer has been mapped as contiguous
+        * into DMA address space.
+        */
+       if (sgt->nents > 1) {
+               dma_addr_t next_addr = sg_dma_address(sgt->sgl);
+               struct scatterlist *s;
+               unsigned int i;
+
+               for_each_sg(sgt->sgl, s, sgt->nents, i) {
+                       if (!sg_dma_len(s))
+                               break;
+                       if (sg_dma_address(s) != next_addr) {
+                               DRM_ERROR("buffer chunks must be mapped contiguously");
+                               return ERR_PTR(-EINVAL);
+                       }
+                       next_addr = sg_dma_address(s) + sg_dma_len(s);
+               }
+       }
+
        exynos_gem = exynos_drm_gem_init(dev, attach->dmabuf->size);
        if (IS_ERR(exynos_gem)) {
                ret = PTR_ERR(exynos_gem);
@@ -480,18 +503,15 @@ exynos_drm_gem_prime_import_sg_table(struct drm_device *dev,
 
        exynos_gem->sgt = sgt;
 
-       if (sgt->nents == 1) {
-               /* always physically continuous memory if sgt->nents is 1. */
-               exynos_gem->flags |= EXYNOS_BO_CONTIG;
-       } else {
-               /*
-                * this case could be CONTIG or NONCONTIG type but for now
-                * sets NONCONTIG.
-                * TODO. we have to find a way that exporter can notify
-                * the type of its own buffer to importer.
-                */
+       /*
+        * Buffer has been mapped as contiguous into DMA address space,
+        * but if there is IOMMU, it can be either CONTIG or NONCONTIG.
+        * We assume a simplified logic below:
+        */
+       if (is_drm_iommu_supported(dev))
                exynos_gem->flags |= EXYNOS_BO_NONCONTIG;
-       }
+       else
+               exynos_gem->flags |= EXYNOS_BO_CONTIG;
 
        return &exynos_gem->base;