On Fri, May 1, 2020 at 4:08 AM Robin Murphy robin.murphy@arm.com wrote:
On 2020-05-01 11:21 am, Brian Starkey wrote:
Hi John,
On Fri, May 01, 2020 at 07:39:48AM +0000, John Stultz wrote:
This patch reworks the cma_heap initialization so that we expose both the default CMA region and any CMA regions tagged with "linux,cma-heap" in the device-tree.
Cc: Rob Herring robh+dt@kernel.org Cc: Sumit Semwal sumit.semwal@linaro.org Cc: "Andrew F. Davis" afd@ti.com Cc: Benjamin Gaignard benjamin.gaignard@linaro.org Cc: Liam Mark lmark@codeaurora.org Cc: Pratik Patel pratikp@codeaurora.org Cc: Laura Abbott labbott@redhat.com Cc: Brian Starkey Brian.Starkey@arm.com Cc: Chenbo Feng fengc@google.com Cc: Alistair Strachan astrachan@google.com Cc: Sandeep Patil sspatil@google.com Cc: Hridya Valsaraju hridya@google.com Cc: Christoph Hellwig hch@lst.de Cc: Marek Szyprowski m.szyprowski@samsung.com Cc: Robin Murphy robin.murphy@arm.com Cc: Andrew Morton akpm@linux-foundation.org Cc: devicetree@vger.kernel.org Cc: dri-devel@lists.freedesktop.org Cc: linux-mm@kvack.org Signed-off-by: John Stultz john.stultz@linaro.org
drivers/dma-buf/heaps/cma_heap.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c index 626cf7fd033a..dd154e2db101 100644 --- a/drivers/dma-buf/heaps/cma_heap.c +++ b/drivers/dma-buf/heaps/cma_heap.c @@ -141,6 +141,11 @@ static int __add_cma_heap(struct cma *cma, void *data) { struct cma_heap *cma_heap; struct dma_heap_export_info exp_info;
- struct cma *default_cma = dev_get_cma_area(NULL);
- /* We only add the default heap and explicitly tagged heaps */
- if (cma != default_cma && !cma_dma_heap_enabled(cma))
return 0;Thinking about the pl111 thread[1], I'm wondering if we should also let drivers call this directly to expose their CMA pools, even if they aren't tagged for dma-heaps in DT. But perhaps that's too close to policy.
That sounds much like what my first thoughts were - apologies if I'm wildly off-base here, but as far as I understand:
- Device drivers know whether they have their own "memory-region" or not.
- Device drivers already have to do *something* to participate in dma-buf.
- Device drivers know best how they make use of both the above.
- Therefore couldn't it be left to drivers to choose whether to register
their CMA regions as heaps, without having to mess with DT at all?
I guess I'm not opposed to this. But I guess I'd like to see some more details? You're thinking the pl111 driver would add the "memory-region" node itself?
Assuming that's the case, my only worry is what if that memory-region node isn't a CMA area, but instead something like a carveout? Does the driver need to parse enough of the dt to figure out where to register the region as a heap?
thanks -john