The width of the "length register" cannot be autodetected, and it is now
specified with a DT property. Add documentation for it.

Cc: Rob Herring <robh...@kernel.org>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: devicet...@vger.kernel.org
Cc: Radhey Shyam Pandey <radhey.shyam.pan...@xilinx.com>
Signed-off-by: Andrea Merello <andrea.mere...@gmail.com>
Reviewed-by: Radhey Shyam Pandey <radhey.shyam.pan...@xilinx.com>
---
Changes in v2:
        - change property name
        - property is now optional
        - cc DT maintainer
Changes in v3:
        - reword
        - cc DT maintainerS and ML
Changes in v4:
        - specify the unit, the valid range and the default value
Changes in v5:
        - commit message trivial fix
        - fix spaces before tab
Changes in v6:
        None
---
 Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt 
b/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
index 174af2c45e77..2fce9fb4b270 100644
--- a/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
+++ b/Documentation/devicetree/bindings/dma/xilinx/xilinx_dma.txt
@@ -41,6 +41,10 @@ Optional properties:
 - xlnx,include-sg: Tells configured for Scatter-mode in
        the hardware.
 Optional properties for AXI DMA:
+- xlnx,sg-length-width: Should be set to the width in bits of the length
+       register as configured in h/w. Takes values {8...26}. If the property
+       is missing or invalid then the default value 23 is used. This is the
+       maximum value that is supported by all IP versions.
 - xlnx,mcdma: Tells whether configured for multi-channel mode in the hardware.
 Optional properties for VDMA:
 - xlnx,flush-fsync: Tells which channel to Flush on Frame sync.
-- 
2.17.1

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