On 4/27/20 11:17 AM, Rob Herring wrote: > On Fri, Apr 24, 2020 at 5:27 PM Andrew F. Davis <afd@xxxxxx> 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@xxxxxx> >> --- >> .../devicetree/bindings/sram/sram.yaml | 8 + > > Separate patch and needs to go to DT list... > Okay, will split for v2. >> 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. > Maybe I could just re-use 'export', right now that property causes the SRAM region to be exported to userspace as a file one can read/write. Exporting via dma-heaps/dma-buf allows more flexibility as one can pass the exported regions to other devices or mmap them directly in userspace. It's up to the SRAM driver maintainer if re-purposing that property in the driver is acceptable. 'Pool' doesn't make much sense to me either, it creates a gen-pool out of the region, but I cant find any users not in combination with the other properties. > What combination of all 3 of these options would be valid? > >From looking at the SRAM driver, it seems each of the option must be used exclusively per region, combining will cause issues. I can update the documentation for the same after we settle on a strategy for this new property. Andrew > Rob > _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
