On Fri, May 01, 2020 at 11:40:16AM -0700, John Stultz wrote: > On Fri, May 1, 2020 at 3:42 AM Brian Starkey <brian.starkey@xxxxxxx> 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 <robh+dt@xxxxxxxxxx> > > > Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx> > > > Cc: "Andrew F. Davis" <afd@xxxxxx> > > > Cc: Benjamin Gaignard <benjamin.gaignard@xxxxxxxxxx> > > > Cc: Liam Mark <lmark@xxxxxxxxxxxxxx> > > > Cc: Pratik Patel <pratikp@xxxxxxxxxxxxxx> > > > Cc: Laura Abbott <labbott@xxxxxxxxxx> > > > Cc: Brian Starkey <Brian.Starkey@xxxxxxx> > > > Cc: Chenbo Feng <fengc@xxxxxxxxxx> > > > Cc: Alistair Strachan <astrachan@xxxxxxxxxx> > > > Cc: Sandeep Patil <sspatil@xxxxxxxxxx> > > > Cc: Hridya Valsaraju <hridya@xxxxxxxxxx> > > > Cc: Christoph Hellwig <hch@xxxxxx> > > > Cc: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > > > Cc: Robin Murphy <robin.murphy@xxxxxxx> > > > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > > > Cc: devicetree@xxxxxxxxxxxxxxx > > > Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx > > > Cc: linux-mm@xxxxxxxxx > > > Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx> > > > --- > > > .../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. > Yeah I'm just wondering if that's "stable" so we can say "the heap will use the node name", or if saying that would cause us a headache in the future. > > 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? Super hand-wavy, something like: /sys/devices/blah/display@2f000000/cma_region is a symlink to /sys/class/dma_heaps/heap_display I think danvet had some thoughts in this vein. Cheers, -Brian > > thanks > -john _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
