Messages in this thread | | | From | Tomi Valkeinen <> | Subject | Re: [PATCH] drm: Fix for GEM buffers with write-combine memory | Date | Fri, 28 May 2021 08:59:15 +0300 |
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On 28/05/2021 02:03, Paul Cercueil wrote: > 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 <paul@crapouillou.net> > Reported-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com> > Fixes: cf8ccbc72d61 ("drm: Add support for GEM buffers backed by non-coherent memory") > --- > drivers/gpu/drm/drm_gem_cma_helper.c | 16 ++++++++++------ > 1 file changed, 10 insertions(+), 6 deletions(-) > > diff --git a/drivers/gpu/drm/drm_gem_cma_helper.c b/drivers/gpu/drm/drm_gem_cma_helper.c > index 235c7a63da2b..4c3772651954 100644 > --- a/drivers/gpu/drm/drm_gem_cma_helper.c > +++ b/drivers/gpu/drm/drm_gem_cma_helper.c > @@ -514,13 +514,17 @@ 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)); > + } else { > + ret = dma_mmap_wc(cma_obj->base.dev->dev, vma, cma_obj->vaddr, > + cma_obj->paddr, vma->vm_end - vma->vm_start); > > - ret = dma_mmap_pages(cma_obj->base.dev->dev, > - vma, vma->vm_end - vma->vm_start, > - virt_to_page(cma_obj->vaddr)); > + } > if (ret) > drm_gem_vm_close(vma); > >
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
and
Tested-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Thanks!
Btw, the kernel-doc for drm_gem_cma_create doesn't quite match, as it says wc is always used.
Tomi
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