Le jeu. 11 mars 2021 à 12:36, Christoph Hellwig [off-list ref] a 
écrit :

On Thu, Mar 11, 2021 at 12:32:27PM +0000, Paul Cercueil wrote:

quoted

 > 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/96a546e7229ec53aadbdb7936d1e5e6cb5958952
 >
 > 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?

You don't - you get it from using virt_to_page on the pointer returned
from dma_alloc_noncoherent.  That beind said to keep the API sane I
should probably add a wrapper that does that for you.

I tested using:

ret = dma_mmap_pages(cma_obj->base.dev->dev,
                     vma, vma->vm_end - vma->vm_start,
                     virt_to_page(cma_obj->vaddr));

It works fine.

I think I can use remap_pfn_range() for now, and switch to your new API 
once it's available in drm-misc-next.

Cheers,
-Paul