Re: [PATCH v2 2/4] dt-bindings: display: msm: Add required dma-range property

On Thu, Feb 20, 2020 at 12:27 PM Jordan Crouse jcrouse@codeaurora.org wrote:

The GMU node now requires a specific dma-range property so that the driver

s/dma-range/dma-ranges/ here and the subject.

can use the DMA API to do the few memory allocations required by the GMU. This sets the IOMMU iova allocator to match the 'uncached' part of the GMU virtual address space.

Sounds like a bunch of kernel things and this is a binding.

v2: Fix the dma-ranges tag. The third pair should be the size.

Signed-off-by: Jordan Crouse jcrouse@codeaurora.org

Documentation/devicetree/bindings/display/msm/gmu.yaml | 10 ++++++++++ 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/display/msm/gmu.yaml b/Documentation/devicetree/bindings/display/msm/gmu.yaml index 776ff92..d11a073 100644 --- a/Documentation/devicetree/bindings/display/msm/gmu.yaml +++ b/Documentation/devicetree/bindings/display/msm/gmu.yaml @@ -83,6 +83,13 @@ properties: Phandle to the OPP table for the available GMU frequencies. Refer to ../../opp/opp.txt for more information.

• dma-ranges:

dma-ranges is a bus property and doesn't go in device nodes (that don't implement a bus like PCI host for example). This would not have even worked a few kernel versions back because the kernel would only start looking for dma-ranges in a parent node.

• $ref: /schemas/types.yaml#/definitions/uint32-array
• description:

•  Describe the dma-address range for the device. This should always
  

•  describe the range between 0x60000000 and 0x80000000 which represents
  

If this is always the region, then why does it need to be in DT? Just set your dma_mask which drivers should be doing if they want anything other than (2^32 - 1). dma-ranges sets the bus_dma_mask.

•  the uncached region of the GMU address space.
  

required:

• compatible
• reg

@@ -95,6 +102,7 @@ required:

• power-domain-names
• iommus
• operating-points-v2

• • dma-ranges

examples:

• |

@@ -127,4 +135,6 @@ examples:

     iommus = <&adreno_smmu 5>;
     operating-points-v2 = <&gmu_opp_table>;

•    dma-ranges = <0 0x60000000 0 0x60000000 0 0x20000000>;
  

  };

-- 2.7.4