1 files changed, 31 insertions, 3 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/dma.c b/drivers/gpu/nvgpu/common/linux/dma.c
index c111d22b..53e54bc6 100644
--- a/drivers/gpu/nvgpu/common/linux/dma.c
+++ b/drivers/gpu/nvgpu/common/linux/dma.c
@@ -227,6 +227,16 @@ int nvgpu_dma_alloc_flags_sys(struct gk20a *g, unsigned long flags,
         }
 
         /*
+         * WAR for IO coherent chips: the DMA API does not seem to generate
+         * mappings that work correctly. Unclear why - Bug ID: 2040115.
+         *
+         * Basically we just tell the DMA API not to map with NO_KERNEL_MAPPING
+         * and then make a vmap() ourselves.
+         */
+        if (nvgpu_is_enabled(g, NVGPU_USE_COHERENT_SYSMEM))
+                flags |= NVGPU_DMA_NO_KERNEL_MAPPING;
+
+        /*
          * Before the debug print so we see this in the total. But during
          * cleanup in the fail path this has to be subtracted.
          */
@@ -260,7 +270,17 @@ int nvgpu_dma_alloc_flags_sys(struct gk20a *g, unsigned long flags,
                                         iova, size, flags);
         }
         if (err)
-                goto fail_free;
+                goto fail_free_dma;
+
+        if (nvgpu_is_enabled(g, NVGPU_USE_COHERENT_SYSMEM)) {
+                mem->cpu_va = vmap(mem->priv.pages,
+                                   size >> PAGE_SHIFT,
+                                   0, PAGE_KERNEL);
+                if (!mem->cpu_va) {
+                        err = -ENOMEM;
+                        goto fail_free_sgt;
+                }
+        }
 
         mem->aligned_size = size;
         mem->aperture = APERTURE_SYSMEM;
@@ -270,12 +290,14 @@ int nvgpu_dma_alloc_flags_sys(struct gk20a *g, unsigned long flags,
 
         return 0;
 
-fail_free:
-        g->dma_memory_used -= mem->aligned_size;
+fail_free_sgt:
+        nvgpu_free_sgtable(g, &mem->priv.sgt);
+fail_free_dma:
         dma_free_attrs(d, size, alloc_ret, iova, NVGPU_DMA_ATTR(dma_attrs));
         mem->cpu_va = NULL;
         mem->priv.sgt = NULL;
         mem->size = 0;
+        g->dma_memory_used -= mem->aligned_size;
         return err;
 }
 
@@ -476,6 +498,12 @@ static void nvgpu_dma_free_sys(struct gk20a *g, struct nvgpu_mem *mem)
         if (!(mem->mem_flags & NVGPU_MEM_FLAG_SHADOW_COPY) &&
             !(mem->mem_flags & __NVGPU_MEM_FLAG_NO_DMA) &&
             (mem->cpu_va || mem->priv.pages)) {
+                /*
+                 * Free side of WAR for bug 2040115.
+                 */
+                if (nvgpu_is_enabled(g, NVGPU_USE_COHERENT_SYSMEM))
+                        vunmap(mem->cpu_va);
+
                 if (mem->priv.flags) {
                         NVGPU_DEFINE_DMA_ATTRS(dma_attrs);