Hi, On Fri, May 01, 2020 at 07:39:46AM +0000, John Stultz wrote: > This patch adds a linux,cma-heap property for CMA reserved memory > regions, which will be used to allow the region to be exposed via > the DMA-BUF Heaps interface > > Cc: Rob Herring <[email protected]> > Cc: Sumit Semwal <[email protected]> > Cc: "Andrew F. Davis" <[email protected]> > Cc: Benjamin Gaignard <[email protected]> > Cc: Liam Mark <[email protected]> > Cc: Pratik Patel <[email protected]> > Cc: Laura Abbott <[email protected]> > Cc: Brian Starkey <[email protected]> > Cc: Chenbo Feng <[email protected]> > Cc: Alistair Strachan <[email protected]> > Cc: Sandeep Patil <[email protected]> > Cc: Hridya Valsaraju <[email protected]> > Cc: Christoph Hellwig <[email protected]> > Cc: Marek Szyprowski <[email protected]> > Cc: Robin Murphy <[email protected]> > Cc: Andrew Morton <[email protected]> > Cc: [email protected] > Cc: [email protected] > Cc: [email protected] > Signed-off-by: John Stultz <[email protected]> > --- > .../devicetree/bindings/reserved-memory/reserved-memory.txt | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git > a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt > b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt > index bac4afa3b197..e97b6a4c3bc0 100644 > --- a/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt > +++ b/Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt > @@ -68,6 +68,9 @@ Linux implementation note: > - If a "linux,cma-default" property is present, then Linux will use the > region for the default pool of the contiguous memory allocator. > > +- If a "linux,cma-heap" property is present, then Linux will expose the > + the CMA region via the DMA-BUF Heaps interface. > +
Would it be useful or even possible to give some indication of what the heap will end up being called? I'm afraid I don't remember what if any conclusions came out of previous discussions on UAPI for heap enumeration. I suppose CMA names haven't been relevant to userspace before, but they perhaps would be with this change. Alternatively, leaving it effectively undefined doesn't tie us down, and something like links in sysfs can be added as a richer API in the future. Cheers, -Brian > - If a "linux,dma-default" property is present, then Linux will use the > region for the default pool of the consistent DMA allocator. > > -- > 2.17.1 >
