Re: [PATCH] misc: sram: Add dma-heap-export reserved SRAM area type

On Fri, Apr 24, 2020 at 5:27 PM Andrew F. Davis afd@ti.com wrote:

This new export type exposes to userspace the SRAM area as a DMA-Heap, this allows for allocations as DMA-BUFs that can be consumed by various DMA-BUF supporting devices.

Signed-off-by: Andrew F. Davis afd@ti.com

.../devicetree/bindings/sram/sram.yaml | 8 +

Separate patch and needs to go to DT list...

drivers/misc/Kconfig | 7 + drivers/misc/Makefile | 1 + drivers/misc/sram-dma-heap.c | 243 ++++++++++++++++++ drivers/misc/sram.c | 20 +- drivers/misc/sram.h | 17 ++ 6 files changed, 292 insertions(+), 4 deletions(-) create mode 100644 drivers/misc/sram-dma-heap.c

diff --git a/Documentation/devicetree/bindings/sram/sram.yaml b/Documentation/devicetree/bindings/sram/sram.yaml index 7b83cc6c9bfa..b8e33c8d205d 100644 --- a/Documentation/devicetree/bindings/sram/sram.yaml +++ b/Documentation/devicetree/bindings/sram/sram.yaml @@ -105,6 +105,14 @@ patternProperties: manipulation of the page attributes. type: boolean

•  dma-heap-export:
  

•    description:
  

•      Similar to 'pool' and 'export' this region will be exported for use
  

•      by drivers, devices, and userspace using the DMA-Heaps framework.
  

•      NOTE: This region must be page aligned on start and end in order to
  

•      properly allow manipulation of the page attributes.
  

•    type: boolean
  

Though I'm not sure this should be in DT. You have to change your firmware to enable a new kernel feature? We also already have 'export' which sounds like the same function. Or 'pool' though reading the description, I don't really understand it's use.

What combination of all 3 of these options would be valid?

Rob