Re: [PATCH v2 3/5] drm: Add and export function drm_gem_cma_mmap_noncoherent

Hi Christoph,

Le jeu. 11 mars 2021 à 12:26, Christoph Hellwig hch@infradead.org a écrit :

...

+int drm_gem_cma_mmap_noncoherent(struct drm_gem_object *obj,

• 		 struct vm_area_struct *vma)
  

+{

• struct drm_gem_cma_object *cma_obj;
• unsigned long pfn;
• int ret;
• /*

• * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(), and 
  

set the

• * vm_pgoff (used as a fake buffer offset by DRM) to 0 as we want 
  

to map

• * the whole buffer.
  

• */
  

• vma->vm_pgoff -= drm_vma_node_start(&obj->vma_node);
• vma->vm_flags &= ~VM_PFNMAP;
• vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
• cma_obj = to_drm_gem_cma_obj(obj);
• pfn = PHYS_PFN(dma_to_phys(cma_obj->base.dev->dev,

cma_obj->paddr));

• ret = remap_pfn_range(vma, vma->vm_start, pfn,

• 	      vma->vm_end - vma->vm_start,
  

• 	      vma->vm_page_prot);
  

dma_to_phys must not be used by drivers.

I have a proper helper for this waiting for users:

http://git.infradead.org/users/hch/misc.git/commitdiff/96a546e7229ec53aadbdb...

If you can confirm the helpers works for you I can try to still sneak it to Linus for 5.12 to ease the merge pain.

I can try. How do I get a page pointer from a dma_addr_t?

-Paul