Commit ab1e9de8 authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Jakub Kicinski
Browse files

dt-bindings: dp83867: add binding for io_impedance_ctrl nvmem cell 



We have a board where measurements indicate that the current three
options - leaving IO_IMPEDANCE_CTRL at the reset value (which is
factory calibrated to a value corresponding to approximately 50 ohms)
or using one of the two boolean properties to set it to the min/max
value - are too coarse.

There is no fixed mapping from register values to values in the range
35-70 ohms; it varies from chip to chip, and even that target range is
approximate. So add a DT binding for an nvmem cell which can be
populated during production with a value suitable for each specific
board.

Reviewed-by: default avatarRob Herring <robh@kernel.org>
Reviewed-by: default avatarAndrew Lunn <andrew@lunn.ch>
Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 9cbc9911

Documentation/devicetree/bindings/net/ti,dp83867.yaml

+15 −3
Original line number Diff line number Diff line
@@ -31,6 +31,16 @@ properties: 
  reg:

    maxItems: 1



  nvmem-cells:

    maxItems: 1

    description:

      Nvmem data cell containing the value to write to the

      IO_IMPEDANCE_CTRL field of the IO_MUX_CFG register.



  nvmem-cell-names:

    items:

      - const: io_impedance_ctrl



  ti,min-output-impedance:

    type: boolean

    description: |
@@ -42,9 +52,11 @@ properties: 
    description: |

      MAC Interface Impedance control to set the programmable output impedance

      to a maximum value (70 ohms).

      Note: ti,min-output-impedance and ti,max-output-impedance are mutually

        exclusive. When both properties are present ti,max-output-impedance

        takes precedence.

      Note: Specifying an io_impedance_ctrl nvmem cell or one of the

        ti,min-output-impedance, ti,max-output-impedance properties

        are mutually exclusive. If more than one is present, an nvmem

        cell takes precedence over ti,max-output-impedance, which in

        turn takes precedence over ti,min-output-impedance.



  tx-fifo-depth:

    $ref: /schemas/types.yaml#/definitions/uint32