From 162ba3bd9dce61889eb739adf2923811dcbeff94 Mon Sep 17 00:00:00 2001 From: Paul Cercueil Date: Fri, 28 May 2021 00:03:34 +0100 Subject: [PATCH] drm: Fix for GEM buffers with write-combine memory The previous commit wrongly assumed that dma_mmap_wc() could be replaced by pgprot_writecombine() + dma_mmap_pages(). It did work on my setup, but did not work everywhere. Use dma_mmap_wc() when the buffer has the write-combine cache attribute, and dma_mmap_pages() when it has the non-coherent cache attribute. Signed-off-by: Paul Cercueil Reported-by: Tomi Valkeinen Reviewed-by: Tomi Valkeinen Tested-by: Tomi Valkeinen Fixes: cf8ccbc72d61 ("drm: Add support for GEM buffers backed by non-coherent memory") Link: https://patchwork.freedesktop.org/patch/msgid/20210527230334.151947-1-paul@crapouillou.net --- drivers/gpu/drm/drm_gem_cma_helper.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c index 235c7a6..4a24af2 100644 --- a/drivers/gpu/drm/drm_gem_cma_helper.c +++ b/drivers/gpu/drm/drm_gem_cma_helper.c @@ -514,13 +514,16 @@ int drm_gem_cma_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma) cma_obj = to_drm_gem_cma_obj(obj); - vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); - if (!cma_obj->map_noncoherent) - vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot); + if (cma_obj->map_noncoherent) { + vma->vm_page_prot = vm_get_page_prot(vma->vm_flags); - ret = dma_mmap_pages(cma_obj->base.dev->dev, - vma, vma->vm_end - vma->vm_start, - virt_to_page(cma_obj->vaddr)); + ret = dma_mmap_pages(cma_obj->base.dev->dev, + vma, vma->vm_end - vma->vm_start, + virt_to_page(cma_obj->vaddr)); + } else { + ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr, + cma_obj->paddr, vma->vm_end - vma->vm_start); + } if (ret) drm_gem_vm_close(vma); -- 2.7.4