On Fri, May 1, 2020 at 3:42 AM Brian Starkey <[email protected]> wrote: > > 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.
So the name we expose is the CMA name itself. So with dt it will be the name of the reserved memory node that the flag property is added to. > 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. Hrm. Mind expanding on what you're thinking here? thanks -john
