Re: [PATCH v6 00/12] dma-buf: heaps: Add support for Tegra VPR

[Will Deacon]

Hi Thierry,

On Fri, Sep 04, 2026 at 12:44:51PM +0200, Thierry Reding wrote:
> This series adds support for the video protection region (VPR) used on
> Tegra SoC devices. It's a special region of memory that is protected
> from accesses by the CPU and used to store DRM protected content (both
> decrypted stream data as well as decoded video frames).
> 
> Patches 1 through 3 add DT binding documentation for the VPR and add the
> VPR to the list of memory-region items for display, host1x and NVDEC.
> 
> The set_direct_map_*_noflush() functions that will be used later in this
> series are exported in patch 4 so that the drivers that use them can be
> built as a module.
> 
> Patch 5 adds bitmap_allocate(), which is like bitmap_allocate_region()
> but works on sizes that are not a power of two.
> 
> The of_node_to_nid() function is exported in patch 6 because it is used
> in a later patch adding a driver that can be built as a module.
> 
> Patch 7 introduces new APIs needed by the Tegra VPR implementation that
> allow memory to be allocated at a fixed offset within a CMA area. Tegra
> VPR needs this in order to implement its own allocator on top of CMA to
> meet the strict hardware requirements. This replaces the dynamic CMA
> area creation patch from earlier versions.

Did you get a chance to see how this could work with Vincent's series:

https://lore.kernel.org/r/20260902104712.2399797-1-vdonnefort@xxxxxxxxxx

? I think that should remove your reliance on can_set_direct_map() and
mean that you can retain block mappings for most of the linear mapping.

Looks like you forgot to cc him, so I added him here.

Cheers,

Will