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Subject[PATCH net-next v2 1/3] dt-bindings: dp83867: add binding for io_impedance_ctrl nvmem cell
Date
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: Rob Herring <robh@kernel.org>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
.../devicetree/bindings/net/ti,dp83867.yaml | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/Documentation/devicetree/bindings/net/ti,dp83867.yaml b/Documentation/devicetree/bindings/net/ti,dp83867.yaml
index 047d757e8d82..76ff08a477ba 100644
--- a/Documentation/devicetree/bindings/net/ti,dp83867.yaml
+++ b/Documentation/devicetree/bindings/net/ti,dp83867.yaml
@@ -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
--
2.31.1
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