drm/nouveau: Support non-coherent hardware

Signed-off-by: Mario Bălănică <mariobalanica02@gmail.com>

Author: mariobalanica

drivers/gpu/drm/nouveau/nouveau_drv.h

@@ -317,6 +317,9 @@ nouveau_drm(struct drm_device *dev)
 static inline bool
 nouveau_drm_use_coherent_gpu_mapping(struct nouveau_drm *drm)
 {
+#ifdef CONFIG_DRM_FORCE_DMA_WRITE_COMBINED_MAPPINGS
+	return false;
+#endif
 	struct nvif_mmu *mmu = &drm->client.mmu;
 	return !(mmu->type[drm->ttm.type_host[0]].type & NVIF_MEM_UNCACHED);
 }

drivers/gpu/drm/nouveau/nouveau_sgdma.c

@@ -72,9 +72,7 @@ nouveau_sgdma_create_ttm(struct ttm_buffer_object *bo, uint32_t page_flags)
 	struct nouveau_sgdma_be *nvbe;
 	enum ttm_caching caching;
 
-	if (nvbo->force_coherent)
-		caching = ttm_uncached;
-	else if (drm->agp.bridge)
+	if (nvbo->force_coherent || drm->agp.bridge)
 		caching = ttm_write_combined;
 	else
 		caching = ttm_cached;

drivers/gpu/drm/nouveau/nvkm/engine/device/pci.c

@@ -1645,7 +1645,8 @@ nvkm_device_pci_func = {
 	.irq = nvkm_device_pci_irq,
 	.resource_addr = nvkm_device_pci_resource_addr,
 	.resource_size = nvkm_device_pci_resource_size,
-	.cpu_coherent = !IS_ENABLED(CONFIG_ARM),
+	.cpu_coherent = !IS_ENABLED(CONFIG_ARM) &&
+			!IS_ENABLED(CONFIG_DRM_FORCE_DMA_WRITE_COMBINED_MAPPINGS),
 };
 
 int

drivers/gpu/drm/nouveau/nvkm/subdev/fb/base.c

@@ -248,9 +248,8 @@ nvkm_fb_dtor(struct nvkm_subdev *subdev)
 	nvkm_falcon_fw_dtor(&fb->vpr_scrubber);
 
 	if (fb->sysmem.flush_page) {
-		dma_unmap_page(subdev->device->dev, fb->sysmem.flush_page_addr,
-			       PAGE_SIZE, DMA_BIDIRECTIONAL);
-		__free_page(fb->sysmem.flush_page);
+		dma_free_coherent(subdev->device->dev, PAGE_SIZE,
+				  fb->sysmem.flush_page, fb->sysmem.flush_page_addr);
 	}
 
 	if (fb->func->dtor)
@@ -279,14 +278,11 @@ nvkm_fb_ctor(const struct nvkm_fb_func *func, struct nvkm_device *device,
 	mutex_init(&fb->tags.mutex);
 
 	if (func->sysmem.flush_page_init) {
-		fb->sysmem.flush_page = alloc_page(GFP_KERNEL | GFP_DMA32 | __GFP_ZERO);
+		fb->sysmem.flush_page = dma_alloc_coherent(device->dev, PAGE_SIZE,
+							   &fb->sysmem.flush_page_addr,
+							   GFP_KERNEL | __GFP_ZERO);
 		if (!fb->sysmem.flush_page)
 			return -ENOMEM;
-
-		fb->sysmem.flush_page_addr = dma_map_page(device->dev, fb->sysmem.flush_page,
-							  0, PAGE_SIZE, DMA_BIDIRECTIONAL);
-		if (dma_mapping_error(device->dev, fb->sysmem.flush_page_addr))
-			return -EFAULT;
 	}
 
 	return 0;

drivers/gpu/drm/nouveau/nvkm/subdev/gsp/rm/r535/gsp.c

@@ -1571,12 +1571,12 @@ nvkm_gsp_sg_free(struct nvkm_device *device, struct sg_table *sgt)
 	struct scatterlist *sgl;
 	int i;
 
-	dma_unmap_sgtable(device->dev, sgt, DMA_BIDIRECTIONAL, 0);
-
 	for_each_sgtable_sg(sgt, sgl, i) {
-		struct page *page = sg_page(sgl);
+		void *cpu_addr = sg_virt(sgl);
+		dma_addr_t dma_addr = sg_dma_address(sgl);
 
-		__free_page(page);
+		if (cpu_addr && dma_addr)
+			dma_free_coherent(device->dev, PAGE_SIZE, cpu_addr, dma_addr);
 	}
 
 	sg_free_table(sgt);
@@ -1594,21 +1594,23 @@ nvkm_gsp_sg(struct nvkm_device *device, u64 size, struct sg_table *sgt)
 		return ret;
 
 	for_each_sgtable_sg(sgt, sgl, i) {
-		struct page *page = alloc_page(GFP_KERNEL);
+		void *cpu_addr;
+		dma_addr_t dma_addr;
 
-		if (!page) {
+		cpu_addr = dma_alloc_coherent(device->dev, PAGE_SIZE,
+					      &dma_addr, GFP_KERNEL);
+		if (!cpu_addr) {
 			nvkm_gsp_sg_free(device, sgt);
 			return -ENOMEM;
 		}
 
-		sg_set_page(sgl, page, PAGE_SIZE, 0);
+		/* XXX: unsafe to use virt_to_page with dma_alloc_coherent */
+		sg_set_page(sgl, virt_to_page(cpu_addr), PAGE_SIZE, 0);
+		sg_dma_address(sgl) = dma_addr;
+		sg_dma_len(sgl) = PAGE_SIZE;
 	}
 
-	ret = dma_map_sgtable(device->dev, sgt, DMA_BIDIRECTIONAL, 0);
-	if (ret)
-		nvkm_gsp_sg_free(device, sgt);
-
-	return ret;
+	return 0;
 }
 
 static void

drivers/gpu/drm/nouveau/nvkm/subdev/mmu/mem.c

@@ -133,8 +133,14 @@ int
 nvkm_mem_map_host(struct nvkm_memory *memory, void **pmap)
 {
 	struct nvkm_mem *mem = nvkm_mem(memory);
+	pgprot_t prot = PAGE_KERNEL;
+
+#ifdef CONFIG_DRM_FORCE_DMA_WRITE_COMBINED_MAPPINGS
+	prot = pgprot_writecombine(prot);
+#endif
+
 	if (mem->mem) {
-		*pmap = vmap(mem->mem, mem->pages, VM_MAP, PAGE_KERNEL);
+		*pmap = vmap(mem->mem, mem->pages, VM_MAP, prot);
 		return *pmap ? 0 : -EFAULT;
 	}
 	return -EINVAL;